Final ReportSummary - ULTRAFIBRE (New manufacturing infrastructure for the production of high quality Natural Fibres)
The three-year project (ULTRAFIBRE) was part-funded by the European Commission under the Seventh Framework Programme and aimed to undertake research to reduce the costs associated with the processing of natural fibres, whilst improving fibre quality, consistency and efficiency. More than EUR 1.7 million of direct financial assistance was provided by the European Commission throughout the duration of the project.
The aim of the ULTRAFIBRE was to develop industrially scalable processes to enable natural fibre growers to process their products into consistent, high quality fibres suitable for supply into the composite materials processors and end-user markets.
The ULTRAFIBRE technology resulted in:
- high quality elementary natural fibres;
- atmospheric plasma treated fibres with improved adhesive properties compared with the untreated fibres;
- yielding higher quality commercial thermoplastic and thermosetting composites;
- bio-composites with improved mechanical properties for new high-tech applications.
The results of the project enable:
- natural fibre growers to process their products into consistent, high quality fibres suitable for the supply into the composite materials processors and end user markets;
- the promotion of the economic prosperity of natural fibre cultivators;
- the promotion of the cooperation between material suppliers, converters, farmers, research centres and end users of the plastic products;
- increased competitiveness of European industry;
- the improvement of skill levels throughout the supply chain.
Project context and objectives:
Fibre reinforced polymers find wide commercial application in the aerospace, leisure, automotive, construction and sporting industries.
In recent years, there has been much interest in developing natural fibre reinforced polymers for a sustainable substitution of synthetic materials and also to develop markets for the non-food crop industry sector. The major impediment to growth facing the European natural fibre sector is the high processing costs needed to produce the fibres themselves. While natural fibres can be used for a wide variety of applications, other fibres are considerably more cost-effective. The growth in the agro-materials / energy crop sector is causing competition for land with food production and this is driving up the costs of both food and non-food crop products. There is an urgent need for more sympathetic integration of food and non-food production; this can be partially achieved through improved process efficiency and productivity. Natural fibre crops cannot be easily separated into fibres of consistent quality. Therefore, to commercially exploit past research investment on the world market and for Europe to reap the sustainability benefits that will result from expansion of the non-food crop sector, new research was required to reduce processing costs and to improve fibre quality, consistency, and efficiency.
The fibre composites industry is running into difficulties of supply at the moment. The worldwide shortage of carbon fibre has been well documented and is a result of a number of factors, including increased demand from China and India. The shortage is driving up the price of fibres, which is hitting manufacturing industries, already under pressure from the emerging world economies. As a result, a project to investigate and encourage the use of natural fibres in composites was extremely timely. Research and development into the application of natural fibres in composites is fragmented, meaning that each fibre research group is attempting individually to address the problem. However, the R&D issues are more fundamental and in the 'pre-competitive domain'. Typical generic technical problems are fibre-polymer bonding, fibre treatment, thermal behaviour, production problems, etc. Sequential and fragmented R&D has inevitably led to inefficient allocation of limited funds and duplicated R&D work. To solve the problems facing the natural fibre sector, input is needed from agro-science, biochemistry, polymer science, chemical engineering, mechanical engineering, production engineering, product design, marketing and management. Thus, a collaborative European wide approach was needed to make a step change in the industrial production of natural fibres. In order for European industry to survive against competition from low-wage economies, it has to innovate and become more knowledge-based.
In order to address the challenges outlined in the previous section, a group of trade associations formed a consortium of research and industrial partners to investigate ways to reduce processing costs and to improve fibre quality and consistency.
Funding was successfully sort from the European Commission and on 1 January 2010 the project named ULTRAFIBRE began.
The aim of the ULTRAFIBRE was to develop industrially scalable processes to enable natural fibre growers to process their products into consistent, high quality fibres suitable for supply into the composite materials processors and end-user markets.
Project objectives
Deliver a scalable, economic, continuous, clean - ultrasonic technology to provide tonnage quantities of high quality fibre, conferring:
- a greater percentage of cleaner and refined elemental fibres, thus improving the quality of bast fibre for the reinforcement of polymer products;
- a 25 % reduction in production costs.
Integration of an atmospheric plasma fibre treatment process conferring:
- a 25 % increase in mechanical properties compared with the untreated fibre;
- commercial thermoplastic and thermosetting composites in targeted end-user applications.
ULTRAFIBRE aimed to assist European natural fibre SMEs in reducing their costs, increasing the yield and quality of natural fibre production, thus improving the state of the art for natural fibre composite materials within the EU. The ULTRAFIBRE project aimed to realise these goals by developing an ultrasonic and atmospheric plasma treatment systems for improved adhesion between polymeric materials and the natural fibres.
The ULTRAFIBRE consortium is comprised of trade associations, small / medium size enterprises (SMEs) and research partners (RTDs):
Trade associations:
- Assocomaplast (Italy)
- European Industrial Hemp Association (Germany)
- British Plastics Federation (United Kingdom).
SMEs:
- AcXys Technologies SA (France)
- Movevirgo Limited (United Kingdom)
- CESAP (Italy).
RTDs:
- Smithers Rapra and Smithers PIRA (UK)
- GreenGran BV (the Netherlands)
- InControl Ultrasonics Ltd (United Kingdom)
- Wageningen UR - Food and Biobased Research (the Netherlands).
Project results:
Ultrasonics:
This section describes the work done in decorticating and treating bast fibre plants such as hemp and flax conferring a higher and more consistent quality of fibre product. Fibre treatment was developed for improving the quality of fibre tow and thus improving its value within the natural fibre composites marketplace. This aspect of the project was very successful and good quality hemp fibre pellets (> 50 kg) were produced at EUR 1/kg and hemp mat (> 20 kg) was produced at EUR 0.45 / m2.
Initially, a hydro-acoustic fibre treatment process using InControl's radial ultrasonic cell was developed to allow controlled processing of Flax and Hemp fibres, yielding enhanced fibre quality for fibre reinforced composite materials with improved mechanical properties.
The hydro-acoustic process uses cavitation forces created by the high power ultrasonic field. Tiny bubbles are created in the fluid medium and collapse with very high localised forces. These cavitation forces clean the fibre surface and help separate the bast fibre bundles, thus increasing the elemental plant fibre content. This has the effect of increasing and cleaning the surface area of the fibre which in turn affords greater interfacial adhesion between the fibre and the polymer matrix.
Early developments centred on a static batch hydro acoustic processor in order to accurately evaluate the effects of the processing conditions. Flax slivers were sourced from beneficiary Ecotex, Poland so that investigations into determining the effects of ultrasonic processing on commercial flax fibre could be evaluated; this batch of flax sliver was used as the reference material for initial evaluations in the project. The water based ultrasonic treatment was found to remove loosely bound material and also dissolved other material into solution from the fibre bundles. This process separated the fibre bundles into elemental plant fibres, thus presenting larger areas of clean fibre surfaces. Further optimisation was undertaken using processing chemicals added to the water which showed greater effects on the separation of the fibre bundles. Processing aids such as sodium hydroxide (3 % and 0.3 % w/w), EDTA and a surfactant (Lipsol) were evaluated; different batches (with different combinations of processing conditions), of fibre were manufactured and assessed using a laser scan technique for measuring the fibre diameter. The volume distribution of the fibre diameter showed an increase in the fibre distribution between 10 - 30 µm, i.e. elemental plant fibre. An increase from 40 % to 75 % single plant fibre was observed on treatment and an overall reduction in mean fibre diameter of 16 % was achieved. Optical microscopy was also used for evaluating the fibre surface. A reduction in adhered cuticle and an increase in fibre fibrillation were seen on treatment.
A second clamped flow through cell was designed using a peristaltic pump and three clamped ultrasonic horn stacks for scale-up purposes.
Further trials were performed using reduced concentration of additives. The sonication time was varied and EDTA was not used due to commercial reasons. A decrease in fibre length and strength was found post processing. This was due to the sodium hydroxide processing aid and the physical entanglement of the fibres on drying. It was found that the optimum processing conditions were in water only, with 180 seconds of sonication.
For commercial reasons processing hemp tow was investigated. Hemp tow is a poor quality but cheap commodity (EUR 0.3 - 0.6) and the hydro acoustic process improved the quality of the fibre by removing the shive content to < 1 %, increasing the content of elemental fibres and cleaning the fibre surface. All three of these improvements in fibre quality lead to an improved fibre-matrix interfacial adhesion and thus improved the flexural strength of hemp / unsaturated polyester (UP) composite by 14 % over non-treated hemp / UP composite.
Development of the bench-top hydro acoustic radial flow cell into a pilot plant processor was performed to allow hemp fibre tow to be refined at sufficient quantities for product and scale-up evaluation which included waste water treatment. Two types of processor were evaluated; a flow through and a batch system. The batch processor was chosen as the final unit. Both hemp fibre mat and hemp fibre pellets were produced at a pilot scale for thermoset composite products (electrical joint connector) and thermoplastic composite products (surf-board fin) evaluations.
A processing line was developed at a pilot scale incorporating a fibre feed system, a batch hydro acoustic fibre processor, a conveyor dryer and a fibre carder. The fibre was either pelletised for thermoplastic composite manufacture or made into a needle-punched mat for sheet moulded compound (SMC) evaluation. Hemp fibre tow was processed in sufficient quantities for analysis of fibre quality and for composite production and evaluation. The hemp fibre was evaluated using Laserscan analysis which quantified the amount of elemental fibre content. The hemp elemental fibre content was increased from 40 to 75 % on treatment with the ultrasonic processor, thus providing a greater surface area for adhesion to the polymer matrix. These three advancements improve the fibre matrix interfacial adhesion. The system was developed so that no expensive processing aids were required and the final pilot plant processor used water only.
The waste effluent from the process was evaluated and found to contain small amounts of solid plant particulates. Pectin, lignin and some aromatic materials were present, (< 2 % of total volume). Disposal of this effluent was found to cost EUR 0.3 / m3 which equates to EUR 0.004 / kg of produced fibre. Recovery methods for the lignin were deemed too uneconomical.
The resources available for the production of a hydro acoustic fibre processing pilot plant were fully utilised and a pilot production line was delivered on schedule so that processed fibre was produced in a relevant form for further evaluations within the project.
Plasma treatment:
Natural fibres do not automatically have good interaction with polymers, which is required for optimal material performance. The ULTRAFIBRE project aims to apply plasma treatment processing for surface modification of flax and hemp fibres in order to obtain improved compatibility and adhesion to polymer matrices. At the same time, treatment should not weaken the fibres, which is often observed after chemical modifications of natural fibres. The goal is to achieve a 25 % increase in mechanical properties compared with the untreated fibre.
Atmospheric pressure plasma, also called soft plasma, allows for high throughput processing, unlike the vacuum plasma technology. Soft plasma treatment is supposed to affect only the very surface of a material, maximum about a few nm. Consequently, the bulk of the fibres will remain unaffected and fibre strength will be retained.
Fibre reinforced composites are known in different forms, as are the fibres incorporated. Short natural fibres are mostly used in extrusion and injection moulded products, as well as in sheet moulding compounds (SMC). Natural fibre roving is of interest for pultruded composites. Non-wovens are used in vacuum formed polyester products, SMCs and natural fibre mat thermoplastic composites (NMT). After consultation with Wageningen UR-FBR, Movevirgo and SRT regarding specific requirements, AcXys has designed and manufactured a plasma treatment unit which allows for the treatment of the three forms of natural fibres which are used in different composite processing techniques: non-woven, roving (sliver) and short fibres. This multi-purpose unit is new in the way that usually plasma treatment units are designed for processing only one form of material. The system used is based on AcXys' atmospheric pressure plasma (APP) technology.
The constructed test unit comprises a 6 cm wide ULD plasma source and a belt system which allows for transportation and plasma treatment of non-wovens, sliver and short natural fibres with a minimum length of 5 - 10 mm. The main feed gas is nitrogen and this may be doped with a wide range of oxidative or reductive gases, such that plasma of a wide range of chemical compositions can be produced. The modifying effect onto material surfaces relates to the plasma chemical composition. The processing rate of the ULTRAFIBRE plasma test unit can be varied in the range of 3 to 25 m/min, but it is no problem to construct a system which allows much lower or even higher rates. At industrial scale, the width of the ULD system may be increased up to 50 cm and a manifold of this width.
At Wageningen UR-FBR, APP has been applied on hemp and flax fibres using a range of feed gas compositions and processing rates. The effect of APP on surface modification of the fibres has been analysed using the X-ray photoelectron spectroscopy (XPS) method, which analyses the outer few nm layer of a material. The chemical composition of hemp and flax fibre surfaces was clearly modified after APP treatment, also after several days and weeks of storage. The level of modification depends on APP parameters, storage conditions and storage time. XPS reveals that the modification vanishes with storage time proceeding. Surface modification was confirmed by physical analysis (water contact angle). At the same time, fibre strength was retained after all plasma treatments evaluated, which means that the reinforcing potential of the fibres is maintained. Fibre surface morphology was evaluated using scanning electron microscopy (SEM), and no effect of plasma on fibre surface morphology could be detected.
Hemp and flax fibre surfaces were treated with APP to achieve improved adhesion to matrices in polymer composites. A range of plasma feed gas compositions was evaluated for application in polypropylene (PP) and polylactic acid (PLA) based injection moulding compounds and unsaturated polyester (UP) based sheet moulding compounds (SMC). The feed gas applied included reducing (H2) and oxidising (O2, N2O, CO2) dopants.
The effect of plasma treatment on fibre-matrix adhesion was evaluated using a single fibre fragmentation tests (SFFT), and a clear positive effect could be determined. Previous research has shown that flexural strength of a fibre reinforced composite may act as a good indicator for fibre-matrix adhesion as well, assuming that fibre strength is not affected by plasma, which appeared to be the case. At the same time, flexural strength is a very important characteristic of composite materials, and a quick test method as well. Therefore, the effect of plasma on fibre-matrix adhesion was evaluated mainly through flexural testing of the fibre reinforced composites.
APP treated hemp and flax fibres were processed into PP and PLA based injection moulding compounds and in UP based SMC composites. For application in the PP and PLA based compounds, fibres were refined prior to plasma treatment in order to avoid fibre refining during compounding and the creation of fresh, untreated fibre surface associated with it.
Plasma treatment of flax and hemp fibres results in a 20 - 24 % increase of composite flexural strength, allowing a 10 % thinner product (= 10 % less material costs) having the same performance under loading.
Plasma treatment of flax fibres results in a 23 % increase of flax-PP composite flexural strength, close to the performance of commercially applied MAPP. Hemp-PLA composite flexural strength increases by 20 - 24 %, allowing a 10 % thinner product (= 10 % less material costs) having the same performance under loading. Hemp-UP based SMC composite flexural strength increases by 20 %. Flax-UP based SMC composite performance reaches 82 % of glass based SMC flexural strength, 115 % of its flexural stiffness and similar heat deflection temperature (HDT) values.
The APP technology only uses electricity and feed gasses. No waste water is produced, except for cooling water. The APP technology can be considered a clean technology. Emissions mainly depend on the feed gas composition. Generally, using compressed air or mixed gases mainly consisting of nitrogen, related harmfulness of such plasma processing is mainly linked to ozone and nitrogen oxides (NOx) emissions. Other emissions may be gaseous substances released from the fibre surface during plasma treatment, for instance CO2, H2O and potentially methanol. Quantified evaluation of plasma emissions shows for pure nitrogen feed gas ozone emission of < 0.05 ppm and NOx could not be detected. These values are within the WHO limitation references. If feed gas contains oxygen, both emission values go up. The level of ozone becomes critical to operators at small amounts of oxygen in the feed gas already. Consequently, extraction is a necessary precaution for APP processing. Ozone is a greenhouse gas, however, also very unstable and no legal pressure to reduce ozone production is known. Even at high contents of oxygen in the feed gas, NOx emissions are not overpassing the WHO safety limits.
Processing:
In the past decade, industry has shown keen interest in the fact that natural fibres, like flax and hemp can be an excellent renewable and sustainable substitute for glass fibres as reinforcement in thermoplastic and thermoset composite materials. Natural fibres have good intrinsic mechanical properties, a low density compared to glass fibres as well as a lower price. Research publications nearly all show a composite stiffness for flax- and hemp fibre reinforced composites close to or even higher than that of commercial glass mat reinforced thermoplastic composites (GMT) and thermoset sheet moulding compound (SMC). The strength of natural fibre composites, however, in most cases was low compared to the strength of glass fibre reinforced composites. This is basically due to the composite-like structure of natural fibres; they are generally not single filaments as most manmade fibres but they can have several physical forms, which depend on the degree of fibre isolation. The physical form of natural fibres should be taken into account when evaluating natural fibre-based composites.
The physical flax- and hemp fibre form being present in composite materials ranges from fibre bundles to elementary fibres, or to even further opened-up shapes. The mechanical properties of these different fibre forms differ strongly. Flax- and hemp fibre bundles are being obtained after the first isolation processes called breaking and scutching. These fibre bundles have an acceptable price-performance ratio and are often commercially used in natural fibre mat reinforced thermoplastic (NMT) and thermoset composites. Their lateral strength is rather poor compared with their axial strength, mainly due to the weak pectin bonds between the so-called 'technical fibres'. The really strong fibres are the elementary fibres, which have an average tensile strength up to 1500 MPa.
The combination of cellulose content per weight unit of a natural fibre source and their fibre form largely determines the amount of reinforcement of extrusion compounded composite granules. For example, cellulose-rich flax bast fibres, which can also be further opened-up to relatively thin elementary fibres, can have a dramatic different reinforcing effect on the thermoplastic matrix compared with softwood flower. The latter has a lower cellulose content and a lower aspect ratio. As a result wood flower will act more like a filler in extrusion compounded granules, whereas flax- and hemp fibres will act more like a true reinforcer.
These intrinsic natural fibre properties should be taken into account when designing a process and product route, which is an alternative to the traditional (f.i. chalk-)filled or glass fibre reinforced composite materials. In order to technically compete with the properties of glass fibre reinforced extrusion compounded granules it is essential to pay as much attention the fibre-matrix dispersion as to its distribution. The latter determines to what extent fibres are homogeneously mixed into the matrix, the former determines the form / aspect ratio or in other words: the extent to which the natural fibre is opened-up to a smaller fibre dimensions. By using the right extrusion compounding technology, annual bast fibres can be both homogeneously mixed through the thermoplastic matrix, and opened up to elementary fibres which have a preferred high aspect ratio. The resulting mechanical properties of the compounded granules are such that they can compete with glass fibre reinforced thermoplastics.
For extrusion compounding, the ULTRAFIBRE project aimed to apply ultrasound- and plasma treatment processing for surface modification of flax and hemp fibres, in order to obtain improved compatibility and adhesion to polymer matrices. At the same time, treatment should not weaken the fibres, what is often observed after chemical modifications of natural fibres. The goal was to achieve a 25 % increase in mechanical properties compared with the untreated fibre.
In close cooperation with SRT and with technical imput from GreenGran and ICMA, regarding specific fibre form requirements, InControl Ultrasonics has designed and manufactured an ultrasound fibre-treatment (USF) unit. It allows for the treatment of several forms of natural fibres which are used in different composite processing techniques.
In order to focus at finding the right fibre form- and resulting fibre / polymer property requirements for future commercial applications, a specific target product has been defined first: surfboard fittings. Based on the currently used polymer materials the products' requirements have been determined in terms of mechanical performance, mainly its required stiffness and strength.
Several formulations were produced at laboratory, pilot and industrial extrusion compounding machineries, using polypropylene and untreated natural fibres. Their properties have been measured and as such set as reference for USF/polymer compounds.
Gravimetric feeding of untreated chopped flax fibres without modification on the lab extruder turned out to be difficult. The fibres are fluffy by nature, causing bridging at the feeder, which also made it difficult to feed at higher fibre contents. 30 wt% chopped flax fibres was achieved as maximum value. Pre-pelletised fibres did not show these limitations when compounding at pilot scale. Here content up to 50 wt% fibres was fed without any problems. Compounding quality has been further improved by selecting the right combination of screw configuration versus PP melt flow. The latter was created by using mixing screw elements, transportation screw elements which vary in screw speed, and by selection medium melt flow PP.
At first it turned out difficult to produce lab scale untreated fibre pellets having equivalent properties needed for industrial compounding. This appeared not a fibre, but instead a machine intrinsic fact. Rather than producing soft pellets the fibres were 'crushed' into powder. In addition, cutting 6mm fibres into smaller sizes, due to its more fluffy nature, created bridging problems during feeding it into the extruder. For continuous extrusion compounding, it was decided to continue the trials at ICMA using pilot and industrial sized compounding machineries.
Although flax had been used as the initial fibre source, the consortium had decided to include and in time change to hemp as the new fibre source. At interim, both fibre sources are used for securing proper benchmark transition. Due to the limited availability of both ultrasound- and plasma treated fibres, all compounds were first produced by using batch-kneaders. This is an efficient way:
(1) to reduce material need; and
(2) screen many different compound compositions.
Also, the properties of thus compounded compositions are representative for continuous extrusion compounding.
Results from the composites' mechanical properties revealed that plasma treatment on flax fibres does increase the composite strength significantly, whereas plasma treatment on hemp fibres does not increase the composite strength. This is explained by the fact that plasma treatment on flax was effectively performed at the surface of clean elementary fibres. In contrast, the hemp fibres are partly unrefined prior to plasma treatment; compounding of thus treated hemp further opens up the fibre bundles, which exposes a large area of non-plasma treated fibre surface.
Even though plasma treatment gives a technical advantage when treating clean elementary fibres and suggesting potential cost advantages by reducing the amount of coupling agent for composite compounding it turned out not to be the route to follow for scaling up the extrusion compounding. This was demonstrated at ICMA and GreenGran during feeding trails at pilot and industrially sized extruders, respectively.
When scaling up the minimum needed fibre throughput is increased. The feeding units require that the fibres are being packed densely in order to meet the minimum throughputs and to prevent the feeders from bridging problems. The following fibre shapes were evaluated:
- reference hemp elementary fibres;
- reference hemp technical fibres, length abour 10 mm;
- reference hemp technical fibres, length about 2-4 mm.
Feeding trials failed for both hemp elementary fibres and for hemp technical fibres, length about 10 mm. Both fibre sources were too fluffy, which caused bridging problems at the feeders' entrance. Also, the throughput was too low for proper compounding.
The technological feeding requirements for scaling up create a dilemma when considering the form of successfully plasma treated fibre. Plasma treatment only worked effectively on elementary fibres, thin layers, whereas extrusion compounding required technical fibres, length about 2 - 4 mm, or for higher densities like fibre pellets.
Plasma treatment is ineffective after fibre pelletising; since fibres in pellet form are needed, the fibres they should be plasma treated prior to pelletising. In doing so, the 'surface-activating' effect of the plasma treatment of largely / completely cancelled by the high mechanical forces being put upon the fibres during pelletising. In other words, plasma treated fibres are not surface-activated anymore after pelletising. The dilemma was discussed with all parties involved. Following testing information, work focused on using plasma treatment specifically for non-woven mats, to produce NMT and SMC composites. For extrusion, compounding only ultrasound treated fibres were further evaluated on their composite performance.
Previous fibre feeding issues had been tackled at SRT by using soft fibre pellets instead. For technology transfer to ICMA, it was essential that fibre feeding issues - especially: bridging problems - would not occur. Having similar order screw diameters at ICMA and taking into account that pellets 6 mm diameter pellets worked at SRT, it was chosen to have maximum 5 mm diameter pellets be produced at an external manufacturer. As a result bridging issues during pellet's feeding at ICMA did not occur.
During scale up trails, three critical processing parameters were varied in order to verify their influence on the resulting composites properties: screw configuration, screw speed and the compounds' throughput. All compounding conditions resulted in homogeneous compounds. Testing the materials' properties demonstrated that, indeed mechanical properties are improved after ultrasound treatment of the hemp fibres. Stiffness has increased from 2600 MPa to 3000 MPa, which is an increase by 15 %; strength remains in the same order of magnitude. The thermal performance has been improved remarkably, showing HDT increase from 99 C to 118 C, which is an increase by 19 %.
Concluding, technology transfer was successfully executed and upscaled hemp ultrasound treated fibre pellets result in similar compound quality compared with lab scale situation.
Using the best performing compounding conditions, pilot scale volumes of granules were produced for injection moulding of demonstrator products. Injection moulding was actually performed on two compound grades:
(1) commercial reference granules' grade from GreenGran; and
(2) best performing ultrasound treated hemp / PP compound.
For both grades, injection moulding went smoothly. From there, a series of surfboard fins were produced from both grades. Both grades resulted in a constant quality of moulded product.
A series of moulded fins, including reference, were tested at DLO for their mechanical performance and comparison with the same measurements - performed at CESAP - on the materials' test bars, directly made the granules. From this the following conclusions were drawn:
- The little spread in mechanical properties, based on sample taking on different fins made from the same grade less than 5% for all values confirms that during compounding all fibres are homogeneously distributed in the PP matrix. This applies for both reference and ultrasound treated hemp sample.
- The ultrasound treated hemp sample has little lower stiffness, strength and impact strength values than its commercial (GreenGran) counterpart.
- Comparing the mechanical properties of the ultrasound treated moulded products with the material properties of the lab scale test bars, it demonstrates that the stiffness of the moulded producted is about 500 MPa higher increase of 17%.
- Comparing the mechanical properties of the ultrasound treated moulded products with the polyamide reference material properties, it demonstrates that both stiffness and strength of the ultrasound treated moulded products are better than what is required. Over 3 GPa versus the required 1,6 GPa for flexural stiffness, and over 67 MPa versus the required 65 MPa for flexural strength.
Composite fabrication:
Two case studies were investigated for product evaluation. Both parts are current products from SME beneficiary Movevirgo's portfolio; a nylon-6, 6 surf-board skeg and a glass fibre reinforced unsaturated polyester (UP) electrical joint connector (EJC). The nylon was replaced by ULTRAFIBRE hemp / polypropylene (PP) composite and the glass fibre / UP composite was replaced by ULTRAFIBRE Hemp / UP.
Hemp tow was processed using the hydro acoustic pilot plant processor; two fibre outputs were produced for thermoplastic and thermosetting composites.
- Hemp (30 %) / polypropylene was compounded at partner ICMA San Giorgio for injection moulding of the surf board skeg.
- Hemp fibre mat was produced for SMC trials and EJC part manufacture.
Both products were evaluated for flexural modulus, flexural strength and impact strength; a flier for these case studies was published, details of which may be seen on the project website: http://www.ultrafibre.org.
The injection moulded hemp/PP skeg showed improved flexural strength and modulus with a decrease in impact strength over the nylon skeg.
The EJC showed properties approaching that of the glass reinforced part; a greater control on the drying process prior to moulding will yield improved properties.
The EJC was used to demonstrate the enhanced fibre / matrix interfacial adhesion gained when plasma functionalisation of the fibre surface at an industrial scale is used.
Hemp fibre mat was produced from sonicated and non-sonicated hemp tow. An industrial plasma treatment trial was performed using AcXys technologies proprietary method. The resulting hemp fibre mats were impregnated with unsaturated polyester resin (the resin is the same as is used in the commercial EJC part with glass fibre). The SMC product was compression moulded into test specimens and into the EJC part for evaluation.
- Flax SMC composite performance reaches 82 % of glass based SMC flexural strength and 115 % of its flexural modulus.
- Ultrasonic treatment of hemp fibres results in a 14 % higher SMC composite flexural strength.
- Pilot scale trials based on thermobonded hemp mats, including industrial non-woven production, plasma treatment, SMC sheet manufacturing and industrial moulding, were performed. The composite products show about 65 % of glass fibre SMC flexural strength and about 80 % of glass fibre SMC modulus. Relatively low performance is considered due to areas with low fibre content. Although variation of glass fibre SMC flexural strength is very high, the average strength of a lab scale produced SMC with high hemp fibre content is similar to that of the commercial glass fibre based SMC.
- Needle punched mats exhibit a low level of stretching during industrial moulding, which triggers tearing apart of the mat, causing inhomogeneous composites with areas poor of fibres and rich in resin. Thermobonded mats are easier to stretch in the mould and SMC cutting and placing is more forgiving. The thermobonded mats used in the present study, however, exhibited rather uneven fibre distribution, which results in inhomogeneous composites as well, showing relatively poor performance.
- Natural fibres contain typically about 10 % of moisture at regular environmental conditions. Previous research has shown that the moisture present in natural fibres, typically about 10 %, limits adhesion between fibres and unsaturated polyester. At lab scale processing, fibres could be easily dried and stored at dry conditions until final SMC moulding. For the pilot scale trials, fibres were not dried as equipment was not adapted to keep fibres dry. Keeping fibres dry at industrial scale requires some modifications of the processing equipment and may result in better composite performance than achieved in the present pilot scale trials.
- The resources available were fully utilised and commercial products were delivered and evaluated on schedule.
- A further trial was performed in order to demonstrate the profile extrusion parameters of hemp reinforced thermoplastic material. A pipe profile demonstrator was chosen. For this trial pipe grade poly-butylene (PB 4235-1 Ivory - Lyondel Bassel) was used.
Pipe grade polybutylene and ultrasonicated hemp tow (30 % w/w) was compounded on a Rondol 21 mm co-rotating twin screw compounder. The pipe was extruded on a Secor 25 mm single screw extruder fitted with a 21 mm pipe die. The cooling / calibrating bath is fitted with an adjustable vacuum chamber with water jets for cooling.
Life cycle analysis (LCA) and life cycle costs (LCC)
In this section of work, the aim was to evaluate the environmental impact of ULTRAFIBRE processes and materials and to analyse the cost of the process.
The LCA current study is considered to be a cradle to gate investigation, since the end of life phase is currently not known. The end point functional unit of this study is 1 kg SMC sheet or 1 kg profile extrusion or injection moulded parts. These endpoints were chosen because in an ideal world, the same physical properties would be taken into account such as stiffness of the sheet and strength of the profile, these properties had not been available for comparison.
The SMC study is based on a simple mass comparison with SMC made with glass fibre at the same addition rate, while the injection moulding study looks at a part of the same size.
The individual processes were modelled in SimaPro and based on information supplied by partners, all information supplied up to the final calculation was included in the study and represented in the final report. Processes are linked and feed each other, in this case in a linear way, one process directly feeds another with added inputs from non ULTRAFIBRE streams.
With the inputs supplied, the software calculates environmental loadings using database values. Two outputs are produced, the first is a midpoint loading based on equivalent emissions such as CO2 for global warming potential. Even though the process may not generate CO2 directly - other emissions are converted into equivalent mass CO2 or other factors so they can be compared directly with other processes.
Other equivalent outputs are:
Abiotic depletion - kg antimony equivalents / kg extraction
Acidification - kg SO2 equivalents / kg emission
Eutrophication - kg PO4 equivalents / kg emission
Global warming (GWP100) - kg carbon dioxide / kg emission
Ozone layer depletion (ODP) - kg CFC-11 equivalent / kg emission
Human toxicity - 1,4-dichlorobenzene equivalents / kg emission
Fresh water aquatic ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Marine aquatic ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Terrestrial ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Photochemical oxidation - kg ethylene equivalents / kg emission.
Figures for the ULTRAFIBRE processes were typically very small in the 10-16 to 10-12 kg/kg range.
The second output is in an endpoint unit called eco points which is used to compare different LCA studies using a common 'unit'. These units are calculated for different weightings and it is important to know which one is used for comparison. For this investigation, the, both mid-point and end-point assessments will be conducted using the CML 2 baseline 2000 v2.05 and the Eco-indicator 99 (H/A) v2.07 methods, recently updated to v2.09. The H/A denotes the 'Hierarchest perspective' and 'Average' methodology.
These methods aim at simplifying the complexity of hundreds of flows into a few environmental areas of interest.
The analysis shows the two SMC products being very close in terms of environmental loading. The resin has a large slice of this loading but as a mass comparison the resin would be the same in each case, this means the fibres must be similar as well. The number of process steps to get from farmed fibre to sheets are numerous and not very refined at this stage whereas the glass production step is commercial and well refined. Further work on the ULTRAFIBRE processes will only decrease the loading and will compare more favourably with the glass.
Costing was performed from a starting point of commercially grown hemp tow, the output from the scutching process. Costs were calculated based on real costs without profit. The results of these calculations are commercially sensitive so are not reported here but they are commercially viable and therefore positive for the project.
Overall, the LCA shows good but not significantly better environmental loading for the hemp fibre and the cost are not prohibitive and even favourable towards the hemp.
Potential impact:
Ultrasonics:
There are three main technological benefits derived from the ultrasonic treatment of natural fibres which enhances the fibre matrix interfacial adhesion:
- cleaning the fibre surface;
- increasing the percentage of elemental fibres;
- reducing the shive content.
The hemp elemental fibre content was increased from 40 to 75 % on treatment with the ultrasonic processor.
The ultrasonic treatment process can produce dry fibre pellets at a cost of EUR 1/kg, and a dry fibre mat at 500g/m2 is EUR 0.75/m2 and at 300g/m2 is EUR 0.45/m2.
The environmental impact of producing hemp for composite production is favourable compared to glass reinforced composites; this is mainly due to the recycling potential at the product's end of life. Otherwise, very little differences were found between glass and hemp fibre reinforced polymers.
The pellet making and drying processes have by far the largest impact for the lab scale production. However, when commercial scale production of the pellets is used, these processes are less significant. This is not surprising as the large scale production of pellets is more efficient.
Plasma:
Pilot scale trials have shown that the APP technology works well for natural fibre non-wovens at a processing width of 25 cm. At industrial scale, the width of the ULD system may be increased up to 50 cm and a manifold of this width. Herewith, the APP has proven to be a scalable technology for modification of hemp and flax fibre surface chemical composition while maintaining fibre strength. This allows production of natural fibre reinforced polymer composites with improved fibre-matrix adhesion and consequently improved mechanical performance. Experimental work performed in the ULTRAFIBRE project shows that APP may improve flexural strength of flax-PP, hemp-PLA and hemp-UP composites by 20 - 24 %, thus allowing 10 % thinner products (= 10 % less material costs) having the same performance under loading. Consequently, APP increases the application window of natural fibre composites. A wider use of natural fibres will bring employment to rural areas where the fibres are grown.
A techno-economic analysis suggests that, at present conditions, the costs of effective plasma treatment of refined fibres for PP based injection moulding compounds will be higher than costs for using commercial MAPP coupling agent. Since for PLA and UP based natural fibre reinforced composites no commercial coupling agent is available, plasma treatment may be an option. Techno-economic evaluation indicates that cost effective APP technology for improved composite performance requires processing speeds to be increased by a factor of 3 - 10 compared to rates found to be effective in the study, while providing the same level of adhesion promotion. Suggestions to improve plasma treatment effectiveness and efficiency by applying reactive couple agents have been listed and initial trials have been performed.
Processing:
Extrusion compounding work performed within the ULTRAFIBRE project, in order to evaluate the performance and potential of USF, shows that it improves the mechanical and thermal properties of flax-PP, and hemp-PP composites by 17 - 19 % This allows making thinner products - suggesting less material costs and less injection moulding operational cost - whilst maintaining the required endproduct performance. Consequently, USF increases the application window of natural fibre composites. A wider use of natural fibres will bring employment to rural areas where the fibres are grown. Furthermore, it widens the perspective of the European injection moulding industry, which nowadays faces much trouble due to the economic crisis and competition from China.
Composite fabrication:
Laboratory-based and pilot trials for the hydro-acoustic treatment of hemp and flax tow result in a marked improvement of fibre quality. The fibre is cleaner with far less surface debris, the process also results in a material with an increase in elemental fibre content from 40 % to 70 % on average for flax. A significant reduction of shive content is also achieved (< 1 %). These enhancements in fibre quality translate to a hemp / UP composite flexural strength improvement of 14 % over non treated hemp. The outputs from the fibre refinement studies were evaluated in this section of work. Two demonstrator parts were chosen for the evaluation of the ULTRAFIBRE materials, namely the surfboard skeg for the thermoplastic sector and an electrical joint connector for the thermosetting composite sector. Both the surfboard skeg and the electrical joint connectors are current products on SME beneficiary Movevirgo's portfolio. Movevirgo are a leading UK green plastic product manufacturer and are keen to replace their products with natural fibre reinforced polymers.
The hemp / PP surf board skeg was produced at a price of EUR 0.204/part assuming that all the processes were completed by one company, i.e. no commercial mark-ups at each processing stage.
- Flax SMC composite performance reaches 82 % of glass based SMC flexural strength and 115 % of its flexural modulus.
- Pilot scale trials based on thermobonded hemp mats, including industrial non-woven production, plasma treatment, SMC sheet manufacturing and industrial moulding, were performed. The composite products show about 65 % of glass fibre SMC flexural strength and about 80 % of glass fibre SMC modulus.
Commercialisation for these products would require one additional person employed at Movevirgo's facility in the South West of England. Also equipment manufacturers for the hydro acoustic and processing / moulding would benefit commercially from this work.
Dissemination and exploitation
The results of the project were disseminated by the trade associations within the consortium (Assocomaplast, EIHA and BPF). Case studies, posters and flyers were made available for download from the project website. A commercial agreement was signed by the consortium, which deals with the future arrangements for selling the technology developed during the project. In addition, a follow-up EC REA demonstration project was applied for in December 2012, based on the commercial development of the atmospheric plasma technologies.
Project website: http://www.ultrafibre.org/
The aim of the ULTRAFIBRE was to develop industrially scalable processes to enable natural fibre growers to process their products into consistent, high quality fibres suitable for supply into the composite materials processors and end-user markets.
The ULTRAFIBRE technology resulted in:
- high quality elementary natural fibres;
- atmospheric plasma treated fibres with improved adhesive properties compared with the untreated fibres;
- yielding higher quality commercial thermoplastic and thermosetting composites;
- bio-composites with improved mechanical properties for new high-tech applications.
The results of the project enable:
- natural fibre growers to process their products into consistent, high quality fibres suitable for the supply into the composite materials processors and end user markets;
- the promotion of the economic prosperity of natural fibre cultivators;
- the promotion of the cooperation between material suppliers, converters, farmers, research centres and end users of the plastic products;
- increased competitiveness of European industry;
- the improvement of skill levels throughout the supply chain.
Project context and objectives:
Fibre reinforced polymers find wide commercial application in the aerospace, leisure, automotive, construction and sporting industries.
In recent years, there has been much interest in developing natural fibre reinforced polymers for a sustainable substitution of synthetic materials and also to develop markets for the non-food crop industry sector. The major impediment to growth facing the European natural fibre sector is the high processing costs needed to produce the fibres themselves. While natural fibres can be used for a wide variety of applications, other fibres are considerably more cost-effective. The growth in the agro-materials / energy crop sector is causing competition for land with food production and this is driving up the costs of both food and non-food crop products. There is an urgent need for more sympathetic integration of food and non-food production; this can be partially achieved through improved process efficiency and productivity. Natural fibre crops cannot be easily separated into fibres of consistent quality. Therefore, to commercially exploit past research investment on the world market and for Europe to reap the sustainability benefits that will result from expansion of the non-food crop sector, new research was required to reduce processing costs and to improve fibre quality, consistency, and efficiency.
The fibre composites industry is running into difficulties of supply at the moment. The worldwide shortage of carbon fibre has been well documented and is a result of a number of factors, including increased demand from China and India. The shortage is driving up the price of fibres, which is hitting manufacturing industries, already under pressure from the emerging world economies. As a result, a project to investigate and encourage the use of natural fibres in composites was extremely timely. Research and development into the application of natural fibres in composites is fragmented, meaning that each fibre research group is attempting individually to address the problem. However, the R&D issues are more fundamental and in the 'pre-competitive domain'. Typical generic technical problems are fibre-polymer bonding, fibre treatment, thermal behaviour, production problems, etc. Sequential and fragmented R&D has inevitably led to inefficient allocation of limited funds and duplicated R&D work. To solve the problems facing the natural fibre sector, input is needed from agro-science, biochemistry, polymer science, chemical engineering, mechanical engineering, production engineering, product design, marketing and management. Thus, a collaborative European wide approach was needed to make a step change in the industrial production of natural fibres. In order for European industry to survive against competition from low-wage economies, it has to innovate and become more knowledge-based.
In order to address the challenges outlined in the previous section, a group of trade associations formed a consortium of research and industrial partners to investigate ways to reduce processing costs and to improve fibre quality and consistency.
Funding was successfully sort from the European Commission and on 1 January 2010 the project named ULTRAFIBRE began.
The aim of the ULTRAFIBRE was to develop industrially scalable processes to enable natural fibre growers to process their products into consistent, high quality fibres suitable for supply into the composite materials processors and end-user markets.
Project objectives
Deliver a scalable, economic, continuous, clean - ultrasonic technology to provide tonnage quantities of high quality fibre, conferring:
- a greater percentage of cleaner and refined elemental fibres, thus improving the quality of bast fibre for the reinforcement of polymer products;
- a 25 % reduction in production costs.
Integration of an atmospheric plasma fibre treatment process conferring:
- a 25 % increase in mechanical properties compared with the untreated fibre;
- commercial thermoplastic and thermosetting composites in targeted end-user applications.
ULTRAFIBRE aimed to assist European natural fibre SMEs in reducing their costs, increasing the yield and quality of natural fibre production, thus improving the state of the art for natural fibre composite materials within the EU. The ULTRAFIBRE project aimed to realise these goals by developing an ultrasonic and atmospheric plasma treatment systems for improved adhesion between polymeric materials and the natural fibres.
The ULTRAFIBRE consortium is comprised of trade associations, small / medium size enterprises (SMEs) and research partners (RTDs):
Trade associations:
- Assocomaplast (Italy)
- European Industrial Hemp Association (Germany)
- British Plastics Federation (United Kingdom).
SMEs:
- AcXys Technologies SA (France)
- Movevirgo Limited (United Kingdom)
- CESAP (Italy).
RTDs:
- Smithers Rapra and Smithers PIRA (UK)
- GreenGran BV (the Netherlands)
- InControl Ultrasonics Ltd (United Kingdom)
- Wageningen UR - Food and Biobased Research (the Netherlands).
Project results:
Ultrasonics:
This section describes the work done in decorticating and treating bast fibre plants such as hemp and flax conferring a higher and more consistent quality of fibre product. Fibre treatment was developed for improving the quality of fibre tow and thus improving its value within the natural fibre composites marketplace. This aspect of the project was very successful and good quality hemp fibre pellets (> 50 kg) were produced at EUR 1/kg and hemp mat (> 20 kg) was produced at EUR 0.45 / m2.
Initially, a hydro-acoustic fibre treatment process using InControl's radial ultrasonic cell was developed to allow controlled processing of Flax and Hemp fibres, yielding enhanced fibre quality for fibre reinforced composite materials with improved mechanical properties.
The hydro-acoustic process uses cavitation forces created by the high power ultrasonic field. Tiny bubbles are created in the fluid medium and collapse with very high localised forces. These cavitation forces clean the fibre surface and help separate the bast fibre bundles, thus increasing the elemental plant fibre content. This has the effect of increasing and cleaning the surface area of the fibre which in turn affords greater interfacial adhesion between the fibre and the polymer matrix.
Early developments centred on a static batch hydro acoustic processor in order to accurately evaluate the effects of the processing conditions. Flax slivers were sourced from beneficiary Ecotex, Poland so that investigations into determining the effects of ultrasonic processing on commercial flax fibre could be evaluated; this batch of flax sliver was used as the reference material for initial evaluations in the project. The water based ultrasonic treatment was found to remove loosely bound material and also dissolved other material into solution from the fibre bundles. This process separated the fibre bundles into elemental plant fibres, thus presenting larger areas of clean fibre surfaces. Further optimisation was undertaken using processing chemicals added to the water which showed greater effects on the separation of the fibre bundles. Processing aids such as sodium hydroxide (3 % and 0.3 % w/w), EDTA and a surfactant (Lipsol) were evaluated; different batches (with different combinations of processing conditions), of fibre were manufactured and assessed using a laser scan technique for measuring the fibre diameter. The volume distribution of the fibre diameter showed an increase in the fibre distribution between 10 - 30 µm, i.e. elemental plant fibre. An increase from 40 % to 75 % single plant fibre was observed on treatment and an overall reduction in mean fibre diameter of 16 % was achieved. Optical microscopy was also used for evaluating the fibre surface. A reduction in adhered cuticle and an increase in fibre fibrillation were seen on treatment.
A second clamped flow through cell was designed using a peristaltic pump and three clamped ultrasonic horn stacks for scale-up purposes.
Further trials were performed using reduced concentration of additives. The sonication time was varied and EDTA was not used due to commercial reasons. A decrease in fibre length and strength was found post processing. This was due to the sodium hydroxide processing aid and the physical entanglement of the fibres on drying. It was found that the optimum processing conditions were in water only, with 180 seconds of sonication.
For commercial reasons processing hemp tow was investigated. Hemp tow is a poor quality but cheap commodity (EUR 0.3 - 0.6) and the hydro acoustic process improved the quality of the fibre by removing the shive content to < 1 %, increasing the content of elemental fibres and cleaning the fibre surface. All three of these improvements in fibre quality lead to an improved fibre-matrix interfacial adhesion and thus improved the flexural strength of hemp / unsaturated polyester (UP) composite by 14 % over non-treated hemp / UP composite.
Development of the bench-top hydro acoustic radial flow cell into a pilot plant processor was performed to allow hemp fibre tow to be refined at sufficient quantities for product and scale-up evaluation which included waste water treatment. Two types of processor were evaluated; a flow through and a batch system. The batch processor was chosen as the final unit. Both hemp fibre mat and hemp fibre pellets were produced at a pilot scale for thermoset composite products (electrical joint connector) and thermoplastic composite products (surf-board fin) evaluations.
A processing line was developed at a pilot scale incorporating a fibre feed system, a batch hydro acoustic fibre processor, a conveyor dryer and a fibre carder. The fibre was either pelletised for thermoplastic composite manufacture or made into a needle-punched mat for sheet moulded compound (SMC) evaluation. Hemp fibre tow was processed in sufficient quantities for analysis of fibre quality and for composite production and evaluation. The hemp fibre was evaluated using Laserscan analysis which quantified the amount of elemental fibre content. The hemp elemental fibre content was increased from 40 to 75 % on treatment with the ultrasonic processor, thus providing a greater surface area for adhesion to the polymer matrix. These three advancements improve the fibre matrix interfacial adhesion. The system was developed so that no expensive processing aids were required and the final pilot plant processor used water only.
The waste effluent from the process was evaluated and found to contain small amounts of solid plant particulates. Pectin, lignin and some aromatic materials were present, (< 2 % of total volume). Disposal of this effluent was found to cost EUR 0.3 / m3 which equates to EUR 0.004 / kg of produced fibre. Recovery methods for the lignin were deemed too uneconomical.
The resources available for the production of a hydro acoustic fibre processing pilot plant were fully utilised and a pilot production line was delivered on schedule so that processed fibre was produced in a relevant form for further evaluations within the project.
Plasma treatment:
Natural fibres do not automatically have good interaction with polymers, which is required for optimal material performance. The ULTRAFIBRE project aims to apply plasma treatment processing for surface modification of flax and hemp fibres in order to obtain improved compatibility and adhesion to polymer matrices. At the same time, treatment should not weaken the fibres, which is often observed after chemical modifications of natural fibres. The goal is to achieve a 25 % increase in mechanical properties compared with the untreated fibre.
Atmospheric pressure plasma, also called soft plasma, allows for high throughput processing, unlike the vacuum plasma technology. Soft plasma treatment is supposed to affect only the very surface of a material, maximum about a few nm. Consequently, the bulk of the fibres will remain unaffected and fibre strength will be retained.
Fibre reinforced composites are known in different forms, as are the fibres incorporated. Short natural fibres are mostly used in extrusion and injection moulded products, as well as in sheet moulding compounds (SMC). Natural fibre roving is of interest for pultruded composites. Non-wovens are used in vacuum formed polyester products, SMCs and natural fibre mat thermoplastic composites (NMT). After consultation with Wageningen UR-FBR, Movevirgo and SRT regarding specific requirements, AcXys has designed and manufactured a plasma treatment unit which allows for the treatment of the three forms of natural fibres which are used in different composite processing techniques: non-woven, roving (sliver) and short fibres. This multi-purpose unit is new in the way that usually plasma treatment units are designed for processing only one form of material. The system used is based on AcXys' atmospheric pressure plasma (APP) technology.
The constructed test unit comprises a 6 cm wide ULD plasma source and a belt system which allows for transportation and plasma treatment of non-wovens, sliver and short natural fibres with a minimum length of 5 - 10 mm. The main feed gas is nitrogen and this may be doped with a wide range of oxidative or reductive gases, such that plasma of a wide range of chemical compositions can be produced. The modifying effect onto material surfaces relates to the plasma chemical composition. The processing rate of the ULTRAFIBRE plasma test unit can be varied in the range of 3 to 25 m/min, but it is no problem to construct a system which allows much lower or even higher rates. At industrial scale, the width of the ULD system may be increased up to 50 cm and a manifold of this width.
At Wageningen UR-FBR, APP has been applied on hemp and flax fibres using a range of feed gas compositions and processing rates. The effect of APP on surface modification of the fibres has been analysed using the X-ray photoelectron spectroscopy (XPS) method, which analyses the outer few nm layer of a material. The chemical composition of hemp and flax fibre surfaces was clearly modified after APP treatment, also after several days and weeks of storage. The level of modification depends on APP parameters, storage conditions and storage time. XPS reveals that the modification vanishes with storage time proceeding. Surface modification was confirmed by physical analysis (water contact angle). At the same time, fibre strength was retained after all plasma treatments evaluated, which means that the reinforcing potential of the fibres is maintained. Fibre surface morphology was evaluated using scanning electron microscopy (SEM), and no effect of plasma on fibre surface morphology could be detected.
Hemp and flax fibre surfaces were treated with APP to achieve improved adhesion to matrices in polymer composites. A range of plasma feed gas compositions was evaluated for application in polypropylene (PP) and polylactic acid (PLA) based injection moulding compounds and unsaturated polyester (UP) based sheet moulding compounds (SMC). The feed gas applied included reducing (H2) and oxidising (O2, N2O, CO2) dopants.
The effect of plasma treatment on fibre-matrix adhesion was evaluated using a single fibre fragmentation tests (SFFT), and a clear positive effect could be determined. Previous research has shown that flexural strength of a fibre reinforced composite may act as a good indicator for fibre-matrix adhesion as well, assuming that fibre strength is not affected by plasma, which appeared to be the case. At the same time, flexural strength is a very important characteristic of composite materials, and a quick test method as well. Therefore, the effect of plasma on fibre-matrix adhesion was evaluated mainly through flexural testing of the fibre reinforced composites.
APP treated hemp and flax fibres were processed into PP and PLA based injection moulding compounds and in UP based SMC composites. For application in the PP and PLA based compounds, fibres were refined prior to plasma treatment in order to avoid fibre refining during compounding and the creation of fresh, untreated fibre surface associated with it.
Plasma treatment of flax and hemp fibres results in a 20 - 24 % increase of composite flexural strength, allowing a 10 % thinner product (= 10 % less material costs) having the same performance under loading.
Plasma treatment of flax fibres results in a 23 % increase of flax-PP composite flexural strength, close to the performance of commercially applied MAPP. Hemp-PLA composite flexural strength increases by 20 - 24 %, allowing a 10 % thinner product (= 10 % less material costs) having the same performance under loading. Hemp-UP based SMC composite flexural strength increases by 20 %. Flax-UP based SMC composite performance reaches 82 % of glass based SMC flexural strength, 115 % of its flexural stiffness and similar heat deflection temperature (HDT) values.
The APP technology only uses electricity and feed gasses. No waste water is produced, except for cooling water. The APP technology can be considered a clean technology. Emissions mainly depend on the feed gas composition. Generally, using compressed air or mixed gases mainly consisting of nitrogen, related harmfulness of such plasma processing is mainly linked to ozone and nitrogen oxides (NOx) emissions. Other emissions may be gaseous substances released from the fibre surface during plasma treatment, for instance CO2, H2O and potentially methanol. Quantified evaluation of plasma emissions shows for pure nitrogen feed gas ozone emission of < 0.05 ppm and NOx could not be detected. These values are within the WHO limitation references. If feed gas contains oxygen, both emission values go up. The level of ozone becomes critical to operators at small amounts of oxygen in the feed gas already. Consequently, extraction is a necessary precaution for APP processing. Ozone is a greenhouse gas, however, also very unstable and no legal pressure to reduce ozone production is known. Even at high contents of oxygen in the feed gas, NOx emissions are not overpassing the WHO safety limits.
Processing:
In the past decade, industry has shown keen interest in the fact that natural fibres, like flax and hemp can be an excellent renewable and sustainable substitute for glass fibres as reinforcement in thermoplastic and thermoset composite materials. Natural fibres have good intrinsic mechanical properties, a low density compared to glass fibres as well as a lower price. Research publications nearly all show a composite stiffness for flax- and hemp fibre reinforced composites close to or even higher than that of commercial glass mat reinforced thermoplastic composites (GMT) and thermoset sheet moulding compound (SMC). The strength of natural fibre composites, however, in most cases was low compared to the strength of glass fibre reinforced composites. This is basically due to the composite-like structure of natural fibres; they are generally not single filaments as most manmade fibres but they can have several physical forms, which depend on the degree of fibre isolation. The physical form of natural fibres should be taken into account when evaluating natural fibre-based composites.
The physical flax- and hemp fibre form being present in composite materials ranges from fibre bundles to elementary fibres, or to even further opened-up shapes. The mechanical properties of these different fibre forms differ strongly. Flax- and hemp fibre bundles are being obtained after the first isolation processes called breaking and scutching. These fibre bundles have an acceptable price-performance ratio and are often commercially used in natural fibre mat reinforced thermoplastic (NMT) and thermoset composites. Their lateral strength is rather poor compared with their axial strength, mainly due to the weak pectin bonds between the so-called 'technical fibres'. The really strong fibres are the elementary fibres, which have an average tensile strength up to 1500 MPa.
The combination of cellulose content per weight unit of a natural fibre source and their fibre form largely determines the amount of reinforcement of extrusion compounded composite granules. For example, cellulose-rich flax bast fibres, which can also be further opened-up to relatively thin elementary fibres, can have a dramatic different reinforcing effect on the thermoplastic matrix compared with softwood flower. The latter has a lower cellulose content and a lower aspect ratio. As a result wood flower will act more like a filler in extrusion compounded granules, whereas flax- and hemp fibres will act more like a true reinforcer.
These intrinsic natural fibre properties should be taken into account when designing a process and product route, which is an alternative to the traditional (f.i. chalk-)filled or glass fibre reinforced composite materials. In order to technically compete with the properties of glass fibre reinforced extrusion compounded granules it is essential to pay as much attention the fibre-matrix dispersion as to its distribution. The latter determines to what extent fibres are homogeneously mixed into the matrix, the former determines the form / aspect ratio or in other words: the extent to which the natural fibre is opened-up to a smaller fibre dimensions. By using the right extrusion compounding technology, annual bast fibres can be both homogeneously mixed through the thermoplastic matrix, and opened up to elementary fibres which have a preferred high aspect ratio. The resulting mechanical properties of the compounded granules are such that they can compete with glass fibre reinforced thermoplastics.
For extrusion compounding, the ULTRAFIBRE project aimed to apply ultrasound- and plasma treatment processing for surface modification of flax and hemp fibres, in order to obtain improved compatibility and adhesion to polymer matrices. At the same time, treatment should not weaken the fibres, what is often observed after chemical modifications of natural fibres. The goal was to achieve a 25 % increase in mechanical properties compared with the untreated fibre.
In close cooperation with SRT and with technical imput from GreenGran and ICMA, regarding specific fibre form requirements, InControl Ultrasonics has designed and manufactured an ultrasound fibre-treatment (USF) unit. It allows for the treatment of several forms of natural fibres which are used in different composite processing techniques.
In order to focus at finding the right fibre form- and resulting fibre / polymer property requirements for future commercial applications, a specific target product has been defined first: surfboard fittings. Based on the currently used polymer materials the products' requirements have been determined in terms of mechanical performance, mainly its required stiffness and strength.
Several formulations were produced at laboratory, pilot and industrial extrusion compounding machineries, using polypropylene and untreated natural fibres. Their properties have been measured and as such set as reference for USF/polymer compounds.
Gravimetric feeding of untreated chopped flax fibres without modification on the lab extruder turned out to be difficult. The fibres are fluffy by nature, causing bridging at the feeder, which also made it difficult to feed at higher fibre contents. 30 wt% chopped flax fibres was achieved as maximum value. Pre-pelletised fibres did not show these limitations when compounding at pilot scale. Here content up to 50 wt% fibres was fed without any problems. Compounding quality has been further improved by selecting the right combination of screw configuration versus PP melt flow. The latter was created by using mixing screw elements, transportation screw elements which vary in screw speed, and by selection medium melt flow PP.
At first it turned out difficult to produce lab scale untreated fibre pellets having equivalent properties needed for industrial compounding. This appeared not a fibre, but instead a machine intrinsic fact. Rather than producing soft pellets the fibres were 'crushed' into powder. In addition, cutting 6mm fibres into smaller sizes, due to its more fluffy nature, created bridging problems during feeding it into the extruder. For continuous extrusion compounding, it was decided to continue the trials at ICMA using pilot and industrial sized compounding machineries.
Although flax had been used as the initial fibre source, the consortium had decided to include and in time change to hemp as the new fibre source. At interim, both fibre sources are used for securing proper benchmark transition. Due to the limited availability of both ultrasound- and plasma treated fibres, all compounds were first produced by using batch-kneaders. This is an efficient way:
(1) to reduce material need; and
(2) screen many different compound compositions.
Also, the properties of thus compounded compositions are representative for continuous extrusion compounding.
Results from the composites' mechanical properties revealed that plasma treatment on flax fibres does increase the composite strength significantly, whereas plasma treatment on hemp fibres does not increase the composite strength. This is explained by the fact that plasma treatment on flax was effectively performed at the surface of clean elementary fibres. In contrast, the hemp fibres are partly unrefined prior to plasma treatment; compounding of thus treated hemp further opens up the fibre bundles, which exposes a large area of non-plasma treated fibre surface.
Even though plasma treatment gives a technical advantage when treating clean elementary fibres and suggesting potential cost advantages by reducing the amount of coupling agent for composite compounding it turned out not to be the route to follow for scaling up the extrusion compounding. This was demonstrated at ICMA and GreenGran during feeding trails at pilot and industrially sized extruders, respectively.
When scaling up the minimum needed fibre throughput is increased. The feeding units require that the fibres are being packed densely in order to meet the minimum throughputs and to prevent the feeders from bridging problems. The following fibre shapes were evaluated:
- reference hemp elementary fibres;
- reference hemp technical fibres, length abour 10 mm;
- reference hemp technical fibres, length about 2-4 mm.
Feeding trials failed for both hemp elementary fibres and for hemp technical fibres, length about 10 mm. Both fibre sources were too fluffy, which caused bridging problems at the feeders' entrance. Also, the throughput was too low for proper compounding.
The technological feeding requirements for scaling up create a dilemma when considering the form of successfully plasma treated fibre. Plasma treatment only worked effectively on elementary fibres, thin layers, whereas extrusion compounding required technical fibres, length about 2 - 4 mm, or for higher densities like fibre pellets.
Plasma treatment is ineffective after fibre pelletising; since fibres in pellet form are needed, the fibres they should be plasma treated prior to pelletising. In doing so, the 'surface-activating' effect of the plasma treatment of largely / completely cancelled by the high mechanical forces being put upon the fibres during pelletising. In other words, plasma treated fibres are not surface-activated anymore after pelletising. The dilemma was discussed with all parties involved. Following testing information, work focused on using plasma treatment specifically for non-woven mats, to produce NMT and SMC composites. For extrusion, compounding only ultrasound treated fibres were further evaluated on their composite performance.
Previous fibre feeding issues had been tackled at SRT by using soft fibre pellets instead. For technology transfer to ICMA, it was essential that fibre feeding issues - especially: bridging problems - would not occur. Having similar order screw diameters at ICMA and taking into account that pellets 6 mm diameter pellets worked at SRT, it was chosen to have maximum 5 mm diameter pellets be produced at an external manufacturer. As a result bridging issues during pellet's feeding at ICMA did not occur.
During scale up trails, three critical processing parameters were varied in order to verify their influence on the resulting composites properties: screw configuration, screw speed and the compounds' throughput. All compounding conditions resulted in homogeneous compounds. Testing the materials' properties demonstrated that, indeed mechanical properties are improved after ultrasound treatment of the hemp fibres. Stiffness has increased from 2600 MPa to 3000 MPa, which is an increase by 15 %; strength remains in the same order of magnitude. The thermal performance has been improved remarkably, showing HDT increase from 99 C to 118 C, which is an increase by 19 %.
Concluding, technology transfer was successfully executed and upscaled hemp ultrasound treated fibre pellets result in similar compound quality compared with lab scale situation.
Using the best performing compounding conditions, pilot scale volumes of granules were produced for injection moulding of demonstrator products. Injection moulding was actually performed on two compound grades:
(1) commercial reference granules' grade from GreenGran; and
(2) best performing ultrasound treated hemp / PP compound.
For both grades, injection moulding went smoothly. From there, a series of surfboard fins were produced from both grades. Both grades resulted in a constant quality of moulded product.
A series of moulded fins, including reference, were tested at DLO for their mechanical performance and comparison with the same measurements - performed at CESAP - on the materials' test bars, directly made the granules. From this the following conclusions were drawn:
- The little spread in mechanical properties, based on sample taking on different fins made from the same grade less than 5% for all values confirms that during compounding all fibres are homogeneously distributed in the PP matrix. This applies for both reference and ultrasound treated hemp sample.
- The ultrasound treated hemp sample has little lower stiffness, strength and impact strength values than its commercial (GreenGran) counterpart.
- Comparing the mechanical properties of the ultrasound treated moulded products with the material properties of the lab scale test bars, it demonstrates that the stiffness of the moulded producted is about 500 MPa higher increase of 17%.
- Comparing the mechanical properties of the ultrasound treated moulded products with the polyamide reference material properties, it demonstrates that both stiffness and strength of the ultrasound treated moulded products are better than what is required. Over 3 GPa versus the required 1,6 GPa for flexural stiffness, and over 67 MPa versus the required 65 MPa for flexural strength.
Composite fabrication:
Two case studies were investigated for product evaluation. Both parts are current products from SME beneficiary Movevirgo's portfolio; a nylon-6, 6 surf-board skeg and a glass fibre reinforced unsaturated polyester (UP) electrical joint connector (EJC). The nylon was replaced by ULTRAFIBRE hemp / polypropylene (PP) composite and the glass fibre / UP composite was replaced by ULTRAFIBRE Hemp / UP.
Hemp tow was processed using the hydro acoustic pilot plant processor; two fibre outputs were produced for thermoplastic and thermosetting composites.
- Hemp (30 %) / polypropylene was compounded at partner ICMA San Giorgio for injection moulding of the surf board skeg.
- Hemp fibre mat was produced for SMC trials and EJC part manufacture.
Both products were evaluated for flexural modulus, flexural strength and impact strength; a flier for these case studies was published, details of which may be seen on the project website: http://www.ultrafibre.org.
The injection moulded hemp/PP skeg showed improved flexural strength and modulus with a decrease in impact strength over the nylon skeg.
The EJC showed properties approaching that of the glass reinforced part; a greater control on the drying process prior to moulding will yield improved properties.
The EJC was used to demonstrate the enhanced fibre / matrix interfacial adhesion gained when plasma functionalisation of the fibre surface at an industrial scale is used.
Hemp fibre mat was produced from sonicated and non-sonicated hemp tow. An industrial plasma treatment trial was performed using AcXys technologies proprietary method. The resulting hemp fibre mats were impregnated with unsaturated polyester resin (the resin is the same as is used in the commercial EJC part with glass fibre). The SMC product was compression moulded into test specimens and into the EJC part for evaluation.
- Flax SMC composite performance reaches 82 % of glass based SMC flexural strength and 115 % of its flexural modulus.
- Ultrasonic treatment of hemp fibres results in a 14 % higher SMC composite flexural strength.
- Pilot scale trials based on thermobonded hemp mats, including industrial non-woven production, plasma treatment, SMC sheet manufacturing and industrial moulding, were performed. The composite products show about 65 % of glass fibre SMC flexural strength and about 80 % of glass fibre SMC modulus. Relatively low performance is considered due to areas with low fibre content. Although variation of glass fibre SMC flexural strength is very high, the average strength of a lab scale produced SMC with high hemp fibre content is similar to that of the commercial glass fibre based SMC.
- Needle punched mats exhibit a low level of stretching during industrial moulding, which triggers tearing apart of the mat, causing inhomogeneous composites with areas poor of fibres and rich in resin. Thermobonded mats are easier to stretch in the mould and SMC cutting and placing is more forgiving. The thermobonded mats used in the present study, however, exhibited rather uneven fibre distribution, which results in inhomogeneous composites as well, showing relatively poor performance.
- Natural fibres contain typically about 10 % of moisture at regular environmental conditions. Previous research has shown that the moisture present in natural fibres, typically about 10 %, limits adhesion between fibres and unsaturated polyester. At lab scale processing, fibres could be easily dried and stored at dry conditions until final SMC moulding. For the pilot scale trials, fibres were not dried as equipment was not adapted to keep fibres dry. Keeping fibres dry at industrial scale requires some modifications of the processing equipment and may result in better composite performance than achieved in the present pilot scale trials.
- The resources available were fully utilised and commercial products were delivered and evaluated on schedule.
- A further trial was performed in order to demonstrate the profile extrusion parameters of hemp reinforced thermoplastic material. A pipe profile demonstrator was chosen. For this trial pipe grade poly-butylene (PB 4235-1 Ivory - Lyondel Bassel) was used.
Pipe grade polybutylene and ultrasonicated hemp tow (30 % w/w) was compounded on a Rondol 21 mm co-rotating twin screw compounder. The pipe was extruded on a Secor 25 mm single screw extruder fitted with a 21 mm pipe die. The cooling / calibrating bath is fitted with an adjustable vacuum chamber with water jets for cooling.
Life cycle analysis (LCA) and life cycle costs (LCC)
In this section of work, the aim was to evaluate the environmental impact of ULTRAFIBRE processes and materials and to analyse the cost of the process.
The LCA current study is considered to be a cradle to gate investigation, since the end of life phase is currently not known. The end point functional unit of this study is 1 kg SMC sheet or 1 kg profile extrusion or injection moulded parts. These endpoints were chosen because in an ideal world, the same physical properties would be taken into account such as stiffness of the sheet and strength of the profile, these properties had not been available for comparison.
The SMC study is based on a simple mass comparison with SMC made with glass fibre at the same addition rate, while the injection moulding study looks at a part of the same size.
The individual processes were modelled in SimaPro and based on information supplied by partners, all information supplied up to the final calculation was included in the study and represented in the final report. Processes are linked and feed each other, in this case in a linear way, one process directly feeds another with added inputs from non ULTRAFIBRE streams.
With the inputs supplied, the software calculates environmental loadings using database values. Two outputs are produced, the first is a midpoint loading based on equivalent emissions such as CO2 for global warming potential. Even though the process may not generate CO2 directly - other emissions are converted into equivalent mass CO2 or other factors so they can be compared directly with other processes.
Other equivalent outputs are:
Abiotic depletion - kg antimony equivalents / kg extraction
Acidification - kg SO2 equivalents / kg emission
Eutrophication - kg PO4 equivalents / kg emission
Global warming (GWP100) - kg carbon dioxide / kg emission
Ozone layer depletion (ODP) - kg CFC-11 equivalent / kg emission
Human toxicity - 1,4-dichlorobenzene equivalents / kg emission
Fresh water aquatic ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Marine aquatic ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Terrestrial ecotoxicity - 1,4-dichlorobenzene equivalents / kg emission
Photochemical oxidation - kg ethylene equivalents / kg emission.
Figures for the ULTRAFIBRE processes were typically very small in the 10-16 to 10-12 kg/kg range.
The second output is in an endpoint unit called eco points which is used to compare different LCA studies using a common 'unit'. These units are calculated for different weightings and it is important to know which one is used for comparison. For this investigation, the, both mid-point and end-point assessments will be conducted using the CML 2 baseline 2000 v2.05 and the Eco-indicator 99 (H/A) v2.07 methods, recently updated to v2.09. The H/A denotes the 'Hierarchest perspective' and 'Average' methodology.
These methods aim at simplifying the complexity of hundreds of flows into a few environmental areas of interest.
The analysis shows the two SMC products being very close in terms of environmental loading. The resin has a large slice of this loading but as a mass comparison the resin would be the same in each case, this means the fibres must be similar as well. The number of process steps to get from farmed fibre to sheets are numerous and not very refined at this stage whereas the glass production step is commercial and well refined. Further work on the ULTRAFIBRE processes will only decrease the loading and will compare more favourably with the glass.
Costing was performed from a starting point of commercially grown hemp tow, the output from the scutching process. Costs were calculated based on real costs without profit. The results of these calculations are commercially sensitive so are not reported here but they are commercially viable and therefore positive for the project.
Overall, the LCA shows good but not significantly better environmental loading for the hemp fibre and the cost are not prohibitive and even favourable towards the hemp.
Potential impact:
Ultrasonics:
There are three main technological benefits derived from the ultrasonic treatment of natural fibres which enhances the fibre matrix interfacial adhesion:
- cleaning the fibre surface;
- increasing the percentage of elemental fibres;
- reducing the shive content.
The hemp elemental fibre content was increased from 40 to 75 % on treatment with the ultrasonic processor.
The ultrasonic treatment process can produce dry fibre pellets at a cost of EUR 1/kg, and a dry fibre mat at 500g/m2 is EUR 0.75/m2 and at 300g/m2 is EUR 0.45/m2.
The environmental impact of producing hemp for composite production is favourable compared to glass reinforced composites; this is mainly due to the recycling potential at the product's end of life. Otherwise, very little differences were found between glass and hemp fibre reinforced polymers.
The pellet making and drying processes have by far the largest impact for the lab scale production. However, when commercial scale production of the pellets is used, these processes are less significant. This is not surprising as the large scale production of pellets is more efficient.
Plasma:
Pilot scale trials have shown that the APP technology works well for natural fibre non-wovens at a processing width of 25 cm. At industrial scale, the width of the ULD system may be increased up to 50 cm and a manifold of this width. Herewith, the APP has proven to be a scalable technology for modification of hemp and flax fibre surface chemical composition while maintaining fibre strength. This allows production of natural fibre reinforced polymer composites with improved fibre-matrix adhesion and consequently improved mechanical performance. Experimental work performed in the ULTRAFIBRE project shows that APP may improve flexural strength of flax-PP, hemp-PLA and hemp-UP composites by 20 - 24 %, thus allowing 10 % thinner products (= 10 % less material costs) having the same performance under loading. Consequently, APP increases the application window of natural fibre composites. A wider use of natural fibres will bring employment to rural areas where the fibres are grown.
A techno-economic analysis suggests that, at present conditions, the costs of effective plasma treatment of refined fibres for PP based injection moulding compounds will be higher than costs for using commercial MAPP coupling agent. Since for PLA and UP based natural fibre reinforced composites no commercial coupling agent is available, plasma treatment may be an option. Techno-economic evaluation indicates that cost effective APP technology for improved composite performance requires processing speeds to be increased by a factor of 3 - 10 compared to rates found to be effective in the study, while providing the same level of adhesion promotion. Suggestions to improve plasma treatment effectiveness and efficiency by applying reactive couple agents have been listed and initial trials have been performed.
Processing:
Extrusion compounding work performed within the ULTRAFIBRE project, in order to evaluate the performance and potential of USF, shows that it improves the mechanical and thermal properties of flax-PP, and hemp-PP composites by 17 - 19 % This allows making thinner products - suggesting less material costs and less injection moulding operational cost - whilst maintaining the required endproduct performance. Consequently, USF increases the application window of natural fibre composites. A wider use of natural fibres will bring employment to rural areas where the fibres are grown. Furthermore, it widens the perspective of the European injection moulding industry, which nowadays faces much trouble due to the economic crisis and competition from China.
Composite fabrication:
Laboratory-based and pilot trials for the hydro-acoustic treatment of hemp and flax tow result in a marked improvement of fibre quality. The fibre is cleaner with far less surface debris, the process also results in a material with an increase in elemental fibre content from 40 % to 70 % on average for flax. A significant reduction of shive content is also achieved (< 1 %). These enhancements in fibre quality translate to a hemp / UP composite flexural strength improvement of 14 % over non treated hemp. The outputs from the fibre refinement studies were evaluated in this section of work. Two demonstrator parts were chosen for the evaluation of the ULTRAFIBRE materials, namely the surfboard skeg for the thermoplastic sector and an electrical joint connector for the thermosetting composite sector. Both the surfboard skeg and the electrical joint connectors are current products on SME beneficiary Movevirgo's portfolio. Movevirgo are a leading UK green plastic product manufacturer and are keen to replace their products with natural fibre reinforced polymers.
The hemp / PP surf board skeg was produced at a price of EUR 0.204/part assuming that all the processes were completed by one company, i.e. no commercial mark-ups at each processing stage.
- Flax SMC composite performance reaches 82 % of glass based SMC flexural strength and 115 % of its flexural modulus.
- Pilot scale trials based on thermobonded hemp mats, including industrial non-woven production, plasma treatment, SMC sheet manufacturing and industrial moulding, were performed. The composite products show about 65 % of glass fibre SMC flexural strength and about 80 % of glass fibre SMC modulus.
Commercialisation for these products would require one additional person employed at Movevirgo's facility in the South West of England. Also equipment manufacturers for the hydro acoustic and processing / moulding would benefit commercially from this work.
Dissemination and exploitation
The results of the project were disseminated by the trade associations within the consortium (Assocomaplast, EIHA and BPF). Case studies, posters and flyers were made available for download from the project website. A commercial agreement was signed by the consortium, which deals with the future arrangements for selling the technology developed during the project. In addition, a follow-up EC REA demonstration project was applied for in December 2012, based on the commercial development of the atmospheric plasma technologies.
Project website: http://www.ultrafibre.org/