Forschungs- & Entwicklungsinformationsdienst der Gemeinschaft - CORDIS

FP7

DEROCA Berichtzusammenfassung

Project ID: 308391
Gefördert unter: FP7-NMP
Land: Belgium

Final Report Summary - DEROCA (Development of safe and eco-friendly flame retardant materials based on CNT co-additives for commodity polymers)

Executive Summary:
Halogenated flame retardants are commonly used in consumer products but they have raised concerns due to their persistency, bioaccumulation on living organisms and their potential toxic effects on human health. In this project, scientists are developing an eco-friendly alternative to the halogenated agents commonly used that are subject to ever-stricter regulation due to potential toxicity.
In this context, the EU has funded the DEROCA (Development of safe and eco-friendly flame retardant materials based on carbon nanotubes co-additives for commodity polymers) project aiming at (i) developing and introducing new safer and more eco-friendly flame retardant through exploiting the synergic effect of multi-walled carbon nanotubes with phosphorus based flame retardants and other new promising additives in intumescent or carbon crust formation systems by promoting a more efficient/cost competitive solution; (ii) developing small scale test methods and models to predict full end product standard scale test results based on small scale tests and (iii) assessing the safe use and absence of toxicity of the new FR materials in production, use and fire situations. Target applications are consumer products, like stadium chairs, corrugated pipes for protecting electrical cables from crushing, wires and cables sheaths, insulation foams, and industrial fan blades for ventilation and air conditioning systems.
Altogether, the EU-funded (FP7) project DEROCA has successfully developed five safe new flame retardant system prototypes, combining industrial multiwall carbon nanotubes with phosphorus-based and other commercially-available flame retardants. In parallel, a new representative lab scale test for cables was developed and validated allowing the rapid development of potential effective formulations.
Concerns over environmental contamination and human health effects of halogenated flame retardants were also assessed. A set of 8 flame retardants was assessed for their human health hazard profile and compared to halogenated flame retardants of concern by following the REACH guidance, the US-EPA Design for Environment and the GreenScreen® Assessment. It was found that the quality of the data and the practice on how to fill data gaps had a major influence on the results. It is thus important to carefully analyze the data used for a comparative hazard assessment before drawing any conclusion. The investigated alternative FRs showed in general a lower hazard profile; the major differences found were persistence and the potential to bioaccumulate.
From an LCA perspective the results are mixed. In some cases the reference product was found to have a slightly lower environmental impact and in other cases the opposite result was found. However, one has to bear in mind that LCA studies focus mainly on emissions like carbon dioxide, sulfur dioxide, phosphorus, nitrogen, and not specifically on toxic emissions like dioxins. The uncertainties were high in most of the LCA results due to difficulties in finding complete data on some of the flame retardants used, but trends across multiple environmental impact categories indicated that using less flame retardant is generally better for the environment. The use of carbon nanotubes in the product formulations has helped to reduce the amount of flame retardant needed to attain the expected fire performance.
DEROCA's new products, tests and simulations are expected to speed the adoption of halogen-free flame retardants in a variety of commodity polymer products. Beneficiaries include the European stakeholders of the value chain of flame retarded products (from raw materials producers to end users via compounders and injection molders), EU academic experts in fire toxicity but especially the EU citizens who will be using safer, less expensive and more eco-friendly products.

Project Context and Objectives:
Because of the enormous threat to human life and safety, fire prevention and containment worldwide amounts to many billions of dollars. Substantial resources are assigned to fire prevention in the home, workplace and public spaces and facilities. Fire safety measures and equipment seek to increase the possibility of survival when fire breaks out. One standard measure is the addition of flame retardant materials during manufacture that will slow fire development and prolong time for evacuation.
Since flame retardants were introduced in the 20th Century, the global flame retardant materials market has grown to more than US $4 billion. However, their environmental and human health safety track record to date is marred: the first flame retardants, polychlorinated biphenyls, were banned in the 1970s, and there are now serious concerns about the various types of compounds that succeeded them. For example, some brominated flame retardants are already banned, having been found to have dioxin-like toxicity and bioaccumulation tendencies.
Halogenated flame retardants are the most widely used flame retardants because of their superior performance and low impact on the properties of the materials with which they are combined. However, some of them are known to generate toxic gases such as hydrochloric and hydrobromic acids, organo-irritants, polychlorodibenzodioxins and polychlorodibenzofurans when burning. Even when not burning, they could be persistent and accumulate and are thus suspected to negatively impact on the human body and the environment.
In response to the intrinsic toxicity of current flame retardants and a stricter chemical regulation regime in Europe, the European Commission (EC) supported 'Development of safe and eco-friendly flame retardant materials based on carbon nanotube co-additives for commodity polymers' (DEROCA) project that was established to develop an alternative, safer flame retardant.
While there are existing safe alternatives to halogenated flame retardants, such as metal hydroxide-based solutions, their suitability is limited. Large quantities are required to be effective as flame retardants, which reduces the mechanical properties of the materials to which they are added in unwanted ways, and are also difficult and energy-intensive to produce. DEROCA has drawn together world-class specialists to ensure that the solutions the project devises are viable against the key criteria of rapid production, added value functionality, environmental safety and cost effectiveness, as well being highly effective flame retardants.
DEROCA has three chief objectives. First, to design new small-scale tests and models for evaluating the environmental and fire hazards of materials that can be extrapolated to large fire testing scenarios; and to show that the new flame retardant materials in production, use and fire situations are safe and reduce toxicity. Second, to develop five prototypes flame retardants/product formulations for the commodity polymer market that significantly reduce the toxicity and opacity of fire fumes, and also improve the mechanical behaviour of materials. Third, the project aims to ensure that companies can switch from using halogenated flame retardants to halogen-free products while guaranteeing the safe use and absence of toxicity of the new flame retardant materials in production, use and fire situations.
The project is exploiting synergies between multi-walled carbon nanotubes as a flame retardant promoter and flame retardant compounds based on phosphorus or other additives in intumescent or carbon crust formation systems. The guiding principle is that, in most polymer contexts, the accumulation of inorganic material during carbon burning inhibits the propagation of flames and so forms a protective surface layer while the flame retardant smothers any flames. Improvement of the fire performance of polymers containing nanoparticles and other flame retardant is mostly associated with a decrease of the peak heat release rate, as measured by cone calorimetry. This effect is usually due to the formation, during thermal decomposition, of a protective barrier (char) on the polymer surface. This limits heat transfer and diffusion of oxygen into the material and volatilisation of combustible degradation products. In the case of burnt materials, where intumescent systems based on phosphorus flame retardant materials are involved, multi-walled carbon nanotubes contribute to consolidation of the burnt material. The formation of a resilient, impervious layer that does not crack when burning is critical to maintain low heat release rates from polymer nanocomposites. DEROCA is also developing tools to support the development and evaluation of new additive flame retardant formulations.
The five product areas on which DEROCA is focusing are: electrical wires and cables; insulation foams; heating, ventilation and air conditioning; corrugated pipes; and consumer goods. Once an efficient solution for each area is identified, it is tested and optimised to enhance its flame retardant efficiency and ensure the cost competitiveness of its manufacture and application. Multi-walled carbon nanotubes are conductive. A lower amount of additives is needed and they can improve mechanical properties. At each stage, the formulation is assessed to ensure safe usage and lack of toxicity during production, in everyday applications and in fire situations.
DEROCA has drawn together world-class specialists to ensure that the solutions the project devises are viable against the key criteria of rapid production, added value functionality, environmental safety and cost effectiveness, as well being highly effective flame retardants.

Project Results:
The EU is funding the DEROCA project aiming at (i) developing small scale test methods and models to predict full end product standard scale test results based on small scale tests and (ii) developing and introducing new safer and more eco-friendly flame retardants through exploiting the synergetic effect of multi-walled carbon nanotubes with phosphorus based flame retardants and other new promising additives in intumescent or carbon crust formation systems by promoting a more efficient/cost competitive solution and; (iii) assessing the safe use and absence of toxicity of the new flame retardant materials in production, use and fire situations.

(i) Development of predictive models for fire classification:
In the past decade, there has been a harmonization of the European fire safety test requirements for different building products, including cables in the frame of the European Construction Products Regulation (CPR). The purpose is to ensure the free movement of all construction products within the European Union by harmonizing national laws with respect to the essential requirements applicable to these products in terms of health and safety. The new standard EN50399 specifies the test apparatus and test procedures for the assessment of the reaction to fire performance of vertically mounted cables to enable classification under CPR. Indeed, cable fires can start either by self-ignition or by exposure to external thermal heating e.g. a fire in real case fire or a burner for standard tests such as EN50399. In both cases, the pyrolysis of the polymeric sheathing and/or insulation materials is responsible for the production of combustible gases. Depending on the fire scenario involved when testing cables, the quantity of combustible gases released will lead to either ignition or flameout. The understanding how a cable behaves when exposed to fire, especially in terms of flame spread, is relatively poor due to the complex geometry and composition of the cables. However, as for every large scale fire testing, this large scale test requires prolonged measurement time and large amount of cables, which is inconsistent with the need to quickly develop new materials with enhanced fire resistance.
During the project, numerical models have been developed using ThermaKin, Comsol®Multiphysics or Fire Dynamics Simulator (FDS) in order to provide a faster and more reliable screening tools of early development formulations. Pyrolysis models are currently being developed in order to be able to simulate the fire behaviour of materials. Using physical, thermal and kinetic parameters of the material and by solving the heat and mass transfer equations, small to large scale test results should be predicted. The results from the models are compared with experimental results from micro-scale or bench-scale tests to evaluate the accuracy of the simulations. Numerous studies previously conducted have successfully modelled mass loss and heat release histories of charring and non-charring polymers exposed to an external heat flux. Similar studies on fire-retarded materials are limited and additional considerations must be made, as such additives can have a large impact on the physical and chemical behaviour of materials when heated. In the literature, studies investigate the capability of the Fire Dynamics Simulator (FDS) and Thermakin models to predict the complex pyrolysis and thus fire behaviour of polymeric materials like poly (butylene terephthalate) (PBT) and PBT reinforced with 30% mass fraction glass fibres (PBT-GF).
Nowadays, the modelling of the pyrolysis of raw polymers or other materials such as woods can be achieved thanks to more powerful models that allow taking into account more phenomena into numerical models, but also more powerful characterization tools such as Solid State Nuclear Magnetic Resonance or Simultaneous Thermal Analysis. Nonetheless, the modelling of flame retarded polymers or a more complex geometry such as a cable is more challenging. Indeed a cable’s materials presents further challenges as the structure and geometry of the whole entity can be irregular and difficult to define. Matala and Hostikka obtained material parameters for a PVC cable using TGA (Thermogravimetric analysis) and the cone calorimeter. The parameters were used to develop pyrolysis models in FDS (Fire Dynamics Simulator), where the geometry of the circular cables was transformed into a planar geometry, more apt for the rectangular mesh of FDS. Pyrolysis models were developed for cables with a sheathing of polyolefins which had been flame retarded with MDH (Magnesium Di-Hydrate). Good agreement with cone calorimeter experiments was obtained and the results can be extrapolated to a large scale cable fire in a tunnel.
The DEROCA project was dedicated to the investigation of the fire behaviour of a material used for cable applications using new small scale methods. First we had studied the behaviour of a cable sheathing made of polyethylene (PE) and ATH (aluminium (tri)hydroxide) with different analytical tools. The chemical and thermo-physical parameters such as heat capacity or thermal conductivity were investigated as a function of temperature. In particular the thermal barrier effect of the ceramic residue left by the degradation of the ATH was quantified in this material as its conductivity (0.21 W/m/K) was found to be constant and relatively low at high temperature compared to initial values (0.21 W/m/K). Similarly, the heat capacity of flame retarded polymer was investigated up to 1200 K through modulated DSC (Differential Scanning Calorimetry). A simple pyrolysis model was developed under Comsol® Multiphysics. This model is able to predict the degradation of a material under simple conditions such as TGA but also in more complex tests such as the cone calorimeter. The parameters previously determined have been used in order to simulate the mass loss and mass loss rate during gasification experiments. It was found that the generally accepted value for gas transport coefficient (1e-5 m2.-1) used for the modelling of non-charring and charring polymer was not relevant. Indeed, the assumption that the gases evolved immediately form the degradation material may be unproved in the case of PE/ATH as the ceramic residue left by the degradation of the ATH can act as a mass transport barrier. Moreover, a new bench-scale test was developed by scaling down the new EN 50399 standard test. This test allows the study of the heat release behaviour coupled with flame spread behaviour. Further investigations will be made with typical cable materials such as polyolefin flame retarded with ATH with or without nanoclays as synergist to find correlations between this bench scale method and large scale test for cables.
In addition, a new small scale test has also been developed to determine the Euroclass of cables by scaling down the large scale apparatus. Actually, the development of more efficient and less toxic cables is of prime interest for the fire safety in buildings. The regulation environment in Europe impose to pass several test: a large scale test method on bunched cables, the EN50399 and a small scale propagation test, the IEC 60332-1 among them. Both tests are irrelevant for new cable screening, either because it is not discriminant for the latter or because it is too time or material consuming to be used in a screening phase. In the DEROCA project, a novel small scale test was developed based on the assumption that the external sheathing is the preponderant component of a cable in terms of fire retardancy as it releases most of the heat of the studied cable but also protects the inner components. Flat specimen 500x21x1 mm3 of external sheathing associated with benchmark cables have then been tested in the novel small scale test and impacted by a methane burner and the HRR (Heat Release Rate) behaviour as well as the flame spread was repeatability observed. It was also proven that depending on the large scale classification of the cables, the fire performances at the small scale on sheathing specimen showed the same classification.
The testing of five benchmark cable materials confirmed the assumption that the testing of sheathing specimen in the small scale test was relevant with regards to the fire scenario involved for the cables in the large scale test. Indeed, strong linear correlations were obtained for the five materials between the small scale test and the large scale EN50399 results. This further validated that down-scaling of the EN50399 test conserves the Euroclass classification. Using the correlations found for the studied cable design, it was then possible to translate the level of performances required in the standard for getting a given Euroclass to levels at the small scale test.
Finally, the small scale test was used for new materials screening and it was shown that it gives additional information compared with traditional bench-small scale test (cone calorimeter) and an optimum formulation was found. New materials based on ATH and two flame retardant additives have then been produced in the frame of a Design of Experiments. The evaluation of their fire performances was performed both using a standard cone calorimeter and the novel bench-scale test. Almost all the results from the cone calorimeter were in the margin of error of the apparatus and not significantly different from formulation to another when clear differences were obtained using the small scale test. Moreover, it was possible to evaluate the flame spread behaviour of the materials in a fire scenario close to that of the certification test. Finally, considering fire retardant, cost and mechanical properties, an expected optimum formulation was selected and tested using the EN50399 procedure in order to validate the approach developed in this study. A reasonable agreement between the predicted results based on testing a cable sheathing specimen in the bench-scale test and the fire performance and Euroclass determined in the large scale test was obtained. A B2ca cable was thus developed. Based on these results, it was demonstrated that it is possible to evaluate and predict the fire performance of complex products based on small scale testing of a relevant component of the product. It would thus be interesting to explore the capabilities of the novel bench-scale test for the prediction of the fire behaviour of cables with another design or with a different sheathing polymer.

(ii) Development of five prototypes for the commodity polymer market:
Formulations for the production of the five prototypes were identified according to the interpretations of the previous rounds of systematic screening. The five prototypes were produced by the industrial partners. No major issues occurred during this phase. Then, tests were conducted for the prototype commercial validation. Altogether, fan blades can have commercial success in demanding applications for potentially explosive environments requiring both electrical dissipative and flame retardant materials. Actually, an innovative flame retardant and electrically dissipative compound was used for the production of TANDEM BLADES SIDE CAPS. The side caps produced from the new formulation complied with the product specification in terms of centrifugal force resistance and electrical dissipation with the additional advantage of flame resistance which is a plus in severe applications/environments.
Regarding corrugated pipes, commercial success of this product is possible in countries like the UK, India, China, and Middle East countries. No processing issues were encountered and the pipe appeared to be of good quality during production even if a bit stiffer compared to standard corrugated pipes. Surface finishing was also fine but with low scratch resistance. The following tests have been performed and passed for prototype validation: impact test, peak load / pressure test, flame test, bending / fatigue test.
For the stadium chair application, even though the main criteria in terms of flame retardancy and mechanical performance were achieved, the surface finishing of the prototype was not so good for commercialisation. In addition, the black colour of the final prototype could also be a brake to the commercialisation of stadium chairs.
For the insulating foam application, the results in term of fire resistivity are not so competitive. Without any improvement, this formulation will not be interesting for the market.
Finally, for the two cable applications (cable 1 used in train, cable 2 used in building), the cable 1 would need further improvement to make it suitable for commercialisation, while cable 2 was much more promising. The prototype of cable 2 fulfils the requirements of the new European class B2 (according to norm EN50399). Only the requirement concerning the dripping during the flame test was not attained. The formulation is still suitable for commercialisation.
In parallel, based on the flammability tests carried out on the different screening samples, an investigation on the synergetic effect between carbon nanotubes and other flame retardants was made. Results showed that NC7000™ carbon nanotubes increase char production and prevent char cracking, and also appear to trap free radicals (so inhibiting flame) and orientate polymer degradation in fire towards carbonisation (char production) rather than volatilisation (flame feeding). The analysis of these results also leads to the conclusion that some families of flame retardant show synergetic effects at specific loadings. At lower loading, there are no effects, while at higher loading, an antagonistic effect could be observed. Any change in commercial flame retardant and/or commercial thermoplastic leads to a new optimum of concentration. Altogether, the synergetic effects between CNTs and other flame retardant are clearly possible but it always dependent on: i) the other flame retardant (e.g. type of flame retardant, commercial grade, presence of co-additives) and ii) the polymer matrix (e.g. type of polymer, commercial grade, addition of additives such as processing aids, mechanical reinforcement… ). Different behaviours could be observed at different carbon nanotube loading. In most cases, it can be shown that:
o At low concentration, no effect is observed
o At optimum concentration (depending on the other flame retardant and the polymer matrix), normally between 0.25 and 1.5 %, synergetic effect
o At higher loading, no effect or antagonistic effect
Therefore, it is highly recommended to have a case by case approach. Once the case is identified (type of flame retardant, type of matrix…), a design of experiment could be completed in order to identify the most suitable formulation.

(iii) Assessment of fire toxicity and overall environmental impact of the new flame retardant formulations developed through life cycle assessment (LCA):
Two other aims of the DEROCA project were the following: 1) to assess and compare the environmental impact of the new DEROCA products with existing reference products and, 2) to conduct a Fire-Life Cycle Assessment (LCA) on one of the products, in which the function of the flame retardant is included in the environmental impact of the product.
Overall, the formulations developed in the DEROCA project resulted in products that met or exceeded the specific set of mechanical and fire performance criteria for each product. In cases where the reference product included halogenated flame retardants, one or more non-halogenated flame retardants were used as a replacement. All of the products included carbon nanotubes in their final formulations.
From an LCA perspective the results are mixed but globally all life cycle assessment reports indicate that reducing the amount of flame retardant in the formulation will reduce the environmental impact of the product, assuming that formulation and processes do not change significantly and that the risk of fire is the same. In some cases the reference product was found to have a slightly lower environmental impact and in other cases the opposite result was found. However, one has to bear in mind that LCA studies focus mainly on emissions like carbon dioxide, sulfur dioxide, phosphorus and nitrogen, and not specifically on toxic emissions like dioxins. The uncertainties were high in most of the LCA results due to difficulties in finding complete data on some of the flame retardants used, but trends across multiple environmental impact categories indicated that using less flame retardant is generally better for the environment. The use of carbon nanotubes in the product formulations has helped to reduce the amount of flame retardant needed to attain the expected fire performance.

Further analyses were conducted on the formulations selected for prototyping to determine their thermal decomposition as well as their flammability properties. Fire behaviour was assessed in terms of time to ignition, heat release, mass loss, and fire growth rate, measured with the cone calorimeter, and supplemented with limiting oxygen index (LOI) and UL-94 measurements. Preliminary testing of ethylene vinyl acetate (EVA) and low-density polyethylene (LDPE) samples was performed in a cone calorimeter. The methodology described in ISO 5660 was optimised following preliminary testing as described below, and all specimens were tested following the optimised method for consistency, with 50 mm distance between the specimen surface and the cone heater, an irradiance of 50 kW m-2, and testing performed in triplicate and results averaged. For centrepoint formulations, the results reported are the averages of each centrepoint.
Neither carbon nanotubes (CNT) nor silicone fire retardant (SiFR) had a significant observable effect on the burning behaviour of EVA/ATH (aluminium (tri)hydroxide) in the cone calorimeter, despite promising LOI results. Following this investigation, SiFR/CNT was determined to be an inadequate flame retardant synergist to the EVA/ATH system for this application, and no further investigation was carried out. The only observable effects were a higher char content in the residue and an initial retention of volatiles due to this char. However, the volatiles were released eventually, once the samples split under the internal pressure of the volatiles. Both additives increased smoke production, which was an undesired effect, with no significant positive effects observed.
There was evidence of some synergistic behaviour between CNT and phosphorus flame retardant (PFR) in EVA/ATH in terms of LOI. However, largely antagonistic effects were observed in cone calorimetry. High loadings of CNT and PFR appeared to be effective in increasing LOI, but in cone testing high loadings of either increased peak heat release rate (pHRR) and heat release, and reduced time to ignition (Tig). In addition to this, PFR did not appear to act in either the condensed phase (via char formation) or the gas phase (via CO-favouring inhibition). No reduction in heat release was observed, and mass loss rates were faster with PFR. These results were not as expected, and may involve ATH, as CNT and PFR have been used successfully in LDPE composites.
Incorporation of CNT in LDPE resulted in up to 22% reduction in Tig. Total heat release (THR) was largely unaffected, indicating no change in total fuel burning. CO and CO2 yields were unaffected by CNT, which indicates that CNTs acted in the condensed phase only via contribution to char formation – which prevented the release of volatiles at the beginning of the test. Addition of PFR delayed Tig and altered the burning behaviour of the LDPE samples. There is evidence that the effectiveness of PFR depended on its co-additives.
In PA 6.6, pHRR increased with CNT loading, most likely due to ineffective char formation above the optimal loading. One possible cause of ineffective char could be the agglomeration of CNT at too high a loading. 3.7% is relatively high, compared with effective results observed elsewhere. There is evidence to suggest that high loadings of red phosphorus (RP) were necessary to counteract the detrimental effects of too high a CNT loading. No significant effect on LOI was observed.

In addition, the release of carbon nanotubes and other chronic toxicants was investigated. In general the same trends have been seen for all polymers in regards to the carbon nanotubes release. Carbon nanotubes were only identified in the ash residue but not in the gas phase and condensed phase. In order to study the potential release of multi-walled carbon nanotubes from burning multi-walled carbon nanotube-polymer nanocomposite pellets at different temperatures, polyamide 6.6 (PA6.6) containing different concentrations of multi-walled carbon nanotubes (0%, 1 and 2%) was burned using the NF X-70-100 test method . Three temperatures were investigated: 400°C, 550°C and 600°C. A combination of microscopic and spectroscopic techniques has been used to identify the nano-sized particles in the complex fire residues. In addition, a new approach that complements electron microscopy data for establishing multi-walled carbon nanotube release and presence is also proposed.
The results obtained from Raman spectroscopy and Scanning electron microscopy have identified multi-walled carbon nanotubes in the ash residue at 550°C, but not at 600°C. However, the catalytic metals were identified as a white residue substance at 600°C.
Additionally, multiwall carbon nanotubes did not affect the identity of organic compound production. For the particle size distribution and concentration, no differences were detected between pure polypropylene and polypropylene with multiwall carbon nanotubes. Some variations have been detected for other polymers for some conditions.
Finally, a risk assessment was carried out by following the guidance for preparing a risk characterisation under the chemicals legislation REACH, consisting of a hazard and exposure assessment. The hazard assessment has been based on a literature research as no experimental data was produced. For the exposure assessment, in addition to literature search, the occupational exposure at the production sites has been estimated by exposure modelling, based on data provided by the project partners in an online questionnaire.
Derived No Effect Levels (DNELs) were compared from the hazard assessment to available exposure values to calculate the risk characterisation ratio (RCR). The DNEL has also been used to derive a hazard score and to rank the flame retardants based on both. A comparative chemical hazard assessment has been carried out by following a similar approach to the Design of Environment (DfE) by U.S.-EPA alternative assessments and the GreenScreen® assessment or by exploiting available assessments by them.
The risk characterisation was carried out for 8 flame retardants which were selected by the project partners based on available information of their hazard properties and technical specifications. These included one halogenated type, Decabromodiphenylethane, which was supposed to be replaced, and 7 halogen-free flame retardants as alternatives to halogenated ones: Aluminium diethylphosphinate, Aluminium hydroxide, Ammonium polyphosphate, Magnesium hydroxide, N-alkoxy hindered amines, Multi-walled carbon nanotubes and Red phosphorus.
A major challenge for our assessment was to correctly identify the chemicals. In some cases only the trade names were given and we had difficulties to correctly assign a specific chemical to that trade name and to use the appropriate data. Some commercial flame retardants are mixtures, for example Exolit or Flamestab whose composition was not exactly known to us, thus we focused our assessment on the principal component.
The possibility to perform a (quantitative) risk characterisation was limited as in general insufficient exposure data were available to be compared to DNELs. Quantitative conclusions were only possible for two flame retardants, red phosphorus and multi-walled carbon nanotubes, for some exposure scenarios. The risk characterisation showed that for some occupational activities, depending on the DNEL applied, the risk for multi-walled carbon nanotubes at the workplace can be considered sufficiently controlled. In other cases further refinement of the exposure assessment would be needed.
In general it was not possible to make a comparison of the flame retardants based on a RCR. Therefore we decided to focus on a comparative hazard assessment. We extended the human hazard assessment by environmental fate and ecotoxicity for the comparison.
The evaluation showed that the major differences between flame retardants of concern and those that are proposed as alternatives are the potential for bioaccumulation and CMR (carcinogenic, mutagenic or reprotoxic) effects. Persistency would be another criterion; however, as all alternatives assessed in DEROCA are inorganics, the criteria for PBT (persistent, bioaccumulative and toxic) and vPvB (very persistent, very bioaccumulative) according to REACH are not applicable to them. The investigated alternatives showed in general a lower hazard profile in comparison to halogenated flame retardants. However we noticed that the conclusions depend on several factors; the availability and quality of data for the relevant hazard endpoints are a major issue. REACH registration dossiers are a good source to find such information. The presented data are however often based on secondary sources or (very) old study reports with little additional information (also on the substance identity). If data are not available for specific endpoints, there are different methods to fill these data gaps. For the assessed flame retardants U.S.-EPA in some cases applied the analogy approach and used data from structurally related substances or decided based on expert judgment. It was not always possible for us, to confirm the U.S.-EPA conclusions and in some cases we came to different results. We also observed that hazard scores can change over time, when new data becomes available or available data is interpreted in a different way. When searching for safer alternatives it is therefore important to not only consult the final benchmark score but also consider the data leading to these results.
In our risk assessments we provide a thorough analysis of the available hazard data of 8 different flame retardants which can be used by our project partners together with the results from the other work packages to evaluate the overall profile of flame retardants to find suitable alternatives to traditional halogenated flame retardants of concern.
Altogether, the human health risk characterisation showed that for some occupational activities, depending on the derived no-effect level applied, the risk for multiwall carbon nanotubes at the workplace can be considered sufficiently controlled. In addition, the investigated alternatives showed in general a lower hazard profile in comparison to halogenated flame retardants.

Potential Impact:
Altogether, the EU-funded (FP7) project DEROCA has successfully developed five safe new flame retardant system prototypes, combining industrial multiwall carbon nanotubes with phosphorus-based and other commercially-available flame retardants. With these results, DEROCA will speed up the replacement of halogen-free flame retardant materials in targeted commodity polymer applications. Due to the large volume of these products, there is clear benefit for citizens. The new alternative formulations developed within the project will facilitate a faster replacement of halogenated flame retardants from products where high fire performance is required to increase the time to escape.
Since commodity polymers are being produced more frequently outside Europe due to cost-competitive feedstock, Europe needs to focus on the preparation of added-value compounds. In DEROCA, the combination of a master batch producer, a compounder, an injection molder and several end-users ensure that all aspects of sustainable production of high added-value products are optimized. The global market of flame retardants in 2007 was estimated to be around $4.23 billion. The European market still represents 24% of the worldwide demand. Halogenated flame retardants represent around 40% of the European market and 61% of the worldwide market. This underlines the fact that Europe is already active in developing new halogen-free flame retardants thanks to stronger safety and environment regulations, but there is still a huge amount of work to do to decrease this share even more. The potential market for the new alternative solutions is estimated to be around $2.15 billion. Safer and more eco-friendly solutions developed in DEROCA will aim to replace at least 10% of this potential market especially but not exclusively in applications requiring multifunctionality.
The achievement of several prototypes is a major outcome for DEROCA partners (specifically for end-users which are strongly interested in the commercial exploitation of those new formulations) but each of them relies on a more in-depth evolution of the technology. Indeed, DEROCA enabled a concrete breakthrough in all addressed domains:
• A new representative lab scale test was developed, tested and validated. This deliverable allows rescreening of potential effective formulations not detected by classical lab-scale fire testing. In addition, this work improves the understanding of the flame retardancy mechanisms and flame retardancy modelling and will also result in faster tests for selection of potential halogen-free flame retardant materials. Consequently, this work will lower costs for testing during the development of a new product as only the final approval tests needs to be conducted and contribute to future standards. This will directly benefit the industrial partners and especially SMEs with the possibility to develop new products in a cost effective way. Some application sectors like the electronic, automotive and construction sectors are facing serious challenges due to the environmental and health and safety issues of the current bromine/chlorine based technology. One of the main reasons the fire toxicity issues have not yet been addressed is the lack of a suitable quantification method. The establishment of a small-scale apparatus to accurately model burning behaviour in large-scale fires will significantly reduce the need for expensive, large-scale tests, particularly at the materials development stage, and inform the design of a new generation of materials and products of reduced environmental impact and combustion-toxicity.
• Simulations of the behaviour of fires based on Thermakin and Comsol codes to better predict flame retardancy of large scale tests was optimized, tested and validated. This computational model allows rescreening of potential effective formulations not detected by classical lab-scale fire testing.
By assessing the flammability and toxicity properties and enabling the prediction of toxic hazards resulting from fire, safer built environments will be created and maintained throughout Europe and the world. This will have three direct impacts: (i) on the manufacturing sector to address areas where fire flammability and toxicity is critical; (ii) to stimulate regulators to ensure that their test protocols are in accordance with the best available information, particularly in high risk applications such as mass transport and defence; (iii) to ensure that the fire safety of new, sustainable low energy buildings is not compromised.
Materials developers will benefit greatly from being able to identify the components responsible for fire gas toxicity in real-scale fires so they can improve the fire safety of their products.
• Acquisition of new knowledge allowing design of safer and eco-friendly, cost-competitive smart materials compliant with fire retardancy requirements brought via LCA and the Fire-LCA on the cables and wires, risk assessment and new information on the toxicity of fumes of those halogen-free flame retardant materials and the potential release of CNTs or additives from burnt materials.
Altogether it is believed that such prediction tools can be of great value to foster the rapid development of cost and safe competitive flame retardant solutions on the EU market.

As for dissemination activities, since the beginning of the project a website was created (http://www.deroca.eu) including a member’s area in which all working documents were shared between the partners. A total of 16 posters and 21 oral presentations were done in well-recognised scientific international events. In parallel, an industrial workshop was hosted by our partner UCLAN in which the DEROCA partners have presented the results’ highlights. Several scientific papers as well as articles dedicated to the popular press were published. Finally a video of one selected case-study (cables) was developed in order to promote the results of the DEROCA project. This was posted on the Nanocyl youtube channel (https://www.youtube.com/watch?v=gU0vo4TZ6xM).

List of Websites:
www.deroca.eu
Project coordinator: julie.muller@nanocyl.com

Verwandte Informationen

Kontakt

Nathalie LUIZI, (R&D Administration)
Tel.: +32 71 75 06 71
Fax: +32 71 75 06 70
E-Mail-Adresse

Fachgebiete

Scientific Research
Datensatznummer: 183689 / Zuletzt geändert am: 2016-06-06
Informationsquelle: SESAM