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FP6

BIOCELSOL Report Summary

Project ID: 505567
Funded under: FP6-NMP
Country: Finland

Final Report Summary - BIOCELSOL (Biotechnological Process for Manufacturing Cellulosic Products with Added Value)

The objectives of the BIOCELSOL project were to understand the enzymatic action on the cellulose and its impact on the structure and processability of cellulose, to develop viable processes for fibres, films, casings, beads and sponges as well as to demonstrate them.

The effect of combined chemical, mechanical and enzymatic treatments to produce cellulose with high alkaline solubility and acceptable viscosity was studied. The pulp characteristics such as alkaline solubility, viscosity, DP, crystallinity, porosity, fibre characteristic and WRV were analysed. As a result of different pre-treatments and enzymatic treatment with experimental or commercial enzymes, cellulose with high solubility and good solution properties was prepared with low yield loss in the enzymatic treatment.

The enzyme-treated pulp was dissolved and the effect of parameters such as cellulose concentration, NaOH content in solvent, total NaOH content of solution, zinc oxide content, as well as time and temperature of dissolution on solution properties was studied and optimised.

Studies on the Biocelsol / viscose blend solutions were also carried out to optimise the composition ratio regarding the rheological properties. The power law exponent was found as a key parameter characterising the processability of solutions and providing important information for fibres, films and other regenerated cellulose product formation.

The end product processes developed had different requirements for the cellulose solution. All the undissolved particles should be removed from the fibre spinning solution, whereas they were not that critical for the processability of films, fibrous casings, beads or sponges. The content of cellulose in each case should be as high as possible for economical reasons, however without increasing the falling ball viscosity too much.

Optimisation of the fibre wet spinning process was done at laboratory scale and the production of fibres for application trials at high-laboratory scale. Additionally, an electrospinning technique for producing cellulosic nanofibres from differently pretreated pulps dissolved was studied at laboratory scale.

The parameters studied in electrospinning trials included pulp characteristics, dissolution procedure, viscosity of solution, surrounding environment, voltage and distance between the nozzle and the collector.

Optimisation of the film production, web impregnation and fibrous casings production were done at laboratory scale. The film production was scaled up to high-laboratory scale, whereas web impregnation was demonstrated in pilot scale and fibrous casings production in industrial scale. Effects of the solution properties, coagulation bath composition, coagulation bath additives and finishing agents on the mechanical properties of the products were studied.

The high-laboratory method to produce Biocelsol film sheets of 50 cm x 50 cm was developed. The Biocelsol films obtained had tenacity higher than 100 MPa and elasticity of 20-30%. A larger amount (750 g) of film sheets were produced for packaging tests.

Development of a coagulation technique for cellulosic beads and sponges from Biocelsol and Biocelsol/viscose blend solutions were done at laboratory scale. The apparatus for bead generation based on rotating atomizer was developed and the process parameters optimised regarding size, shape, and surface chemistry of the beads. The obtained tablets were tested for their properties and the results demonstrated that they fulfilled the pharmaceutical regulations.

Additionally, an electro spraying technique to produce beads was studied. As the aqueous Biocelsol solution does not solidify in the air, the sulphuric acid bath was used as a collector. The shape and size of beads were possible to control by cellulose concentration and the distance between the nozzle and the bath. The beads obtained were smaller than the ones from rotating atomizer and they tended to agglomerate when dried.

Development of a sponge making procedure was carried out by optimising the process parameters known from the production of viscose sponges. It turned out that the Biocelsol sponge with adequate strength could not be prepared. Only by adding some supportive cotton fibres, it was possible to produce Biocelsol sponge, although the structure was not homogeneous due to uneven mixing technique.

The produced Biocelsol beads and sponges were biocompatible due to elimination of CS2 as compared to the respective products from the viscose solution. Thus, they should be suitable for various pharmaceutical, medical, and clinical applications, for example tablet production and aerosol applications (beads), and wound healing (sponges).

Procedure to prepare cellulose with high solubility and good solution properties in aqueous alkali was developed with low yield loss in the enzymatic treatment. The procedure included pretreatment of dissolving type pulp and enzymatic treatment with commercial or experimental enzymes. The treated cellulose was dissolved to obtain solution containing 4-6.5% cellulose, 0-1.3% zinc oxide and 7.8% sodium hydroxide depending on the application. The lowest alkali to cellulose ratio obtained was 1.2, which was higher than targeted level.

Processes for fibres, films, impregnated webs, fibrous casings, beads and sponges were developed utilising the enzyme-treated pulp without any need of carbon disulphide.

Trials to impregnate paper web with Biocelsol solution did not succeed because the web did not stand the high alkalinity of the Biocelsol solution. Instead, the industrial scale trial to produce fibrous casings by coating the viscose bonded paper web with Biocelsol solution went surprisingly well, even though the solution parameters were not yet optimal. Beads were successfully prepared from Biocelsol solution and their characteristics turned out to be different and probably better than of the beads made from the viscose solution. Instead, the sponge production from the Biocelsol solution was more difficult than expected and needs more studies to obtain desired results.

The direct impact of the Biocelsol project on the current industry fields which produce dissolving type pulp, use the viscose technology for fibres, films or fibrous casings or produce different end product from viscose fibres, was small. However, if the research and development gaps identified were fulfilled during the following projects, the impact would be multiplied.

With the successful scaling up of the best pretreatment method there would be sufficient amount of treated pulp for pilot scale fibre, film and fibrous casings trials, which in turn would ensure a proper process optimisation and provide more information about the feasibility of the processes.

Additionally, the industry producing dissolving type pulp for the viscose based processes would have a new type of product in their selection, which should increase the turn over of the companies.

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TUOTEKEHITYS OY TAMLINK
33721 TAMPERE
Finland
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