Novel biotechnical processes for wool felting

Technical assessment of the enzyme treated wool samples (raw, pre-felted, felted) by W-CIE, colour, density, permeability, absorbency, microscopy; Analytical assessment on fiber level by SEM, AFM, SDS-PAGE, MALDI-ToF, XPS. SEM-pictures were taken from all samples to analyse the morphology. Differences between single fabrication steps and different treatments were documented. The alkali solubility was tested and compared to a reference standard cloth (IWTO 4-60). The results show an increase after carbonisation not obligatory being a result of the carbonisation process. Alkali solubility increases also by heating, light exposure or acid, oxidative or reductive influences. For felted samples from Abel a determination of water absorption (DIN 53923) and suction effect (DIN 53924) was done. Differences between the single fabrication steps were noticeable. Sets of piano hammer heads with different densities were tested for their tendency of tension release. Cuttings were set along the most stressed area of hammer heads and tension release was watched closely. The hammer heads show no significant differences in their behaviour of tension release. The amino acid pattern of several samples were determined and compared with mean values of a reference. Significant differences were only seen for cysteic acid, which can be the result of an oxidative process.

Untreated and protease treated felted yarn and prefelted area-measured material samples when dyed in competition show enhanced colour uptake of the enzyme treated samples; all protease treated samples dyed with different dyestuffs show a deeper colouration. Concerning the low-temperature dyeing it was elucidated at lab scale that dyeing at 60 °C led to uneven colouration. However, protease treated prefelted area-measured material dyed at 90 °C gave the same or even slightly better dyebath exhaustion that the untreated reference dyed at 98 °C. The processes were transferred to pilot scale showing that the results obtained on lab scale with felted samples cannot be transferred to unfelted samples at pilot scale; severe fiber damaging was observed. As a result it was concluded that for all scaling up, change of start material or machinery where the protease treatment is performed the parameter sets (temperature, time, buffer, kind of protease) have to be optimised separately

Ring burrs and grass seeds have been treated with commercial cellulase (Econase CE), xylanases (Ecopulp X 200, Ecopulp TX-200 C) and pectinase (Pectinex 3 XL) products alone and in combinations. The degradation of vegetable material has been monitored by measuring reducing sugars and soluble carbohydrate content of the treatment solution as well as weight loss of the material. The effect of cutinase and lipase in combination with pectinase, xylanase and cellulose on the weight loss of grass seeds was evaluated. Treatment with lipase or cutinase in combination with cellulase, pectinase and xylanase increased weight loss as compared with cellulase-pectinase-xylanase combination. 10% weight loss was obtained with the combination in this lab scale treatment. The reactivity of peroxidase and laccase alone and in combination with different mediators towards ring burrs was determined by measuring residual peroxide (peroxidase) and oxygen consumption (laccase) and by measuring weight loss of the material and abs 280 of the treatment liquid. Reactivity of peroxidase towards VM was detected as an increase in peroxide consumption and weight loss of the burrs. Slight increase in weight loss of the laccase + NHA mediator treated material and in abs 280 was detected suggesting removal of lignin.

Enzymes to be used in the finishing of prefelts or the felting process itself were screened and characterised. Commercially available and experimental enzymes were selected. The enzymes selected for felting were transglutaminases, laccases, peroxidases, proteases. Different types of enzymes acting on remaining spinning additives (oils) and wool fats, i.e. lipases were also selected. The enzyme activities and optimal working conditions were determined. To determine the mode of catalytic action of the laccase on the spinning oil also advanced analytical techniques, such GC/MS were used. The potential of different structure modifying and potentially cross-linking enzymes (e.g. transglutaminase, laccase, peroxidase) was evaluated on wool felting. A basic optimization of the treatment conditions like amount of enzymes, temperature, pH, mechanical agitation, time, additives, amount of felting steps was carried out. The degree of felting was evaluated. The pilot-scale felting processes were established based on lab-scale trials by the SME partners. The final product quality was compared to conventionally processed felt products.

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