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Desenvolvimento de fibras proteicas por wet spinning
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Abstract(s)
O presente trabalho teve como objetivo o desenvolvimento de fibras proteicas por wet spinning. Numa primeira fase, utilizou-se gelatina comercial com o objetivo de encontrar os parâmetros ideais à produção de fibras, como a temperatura e o tipo de solvente a serem utilizados. Numa segunda fase, utilizou-se aparas de couro bovino acabado para produzir fibras proteicas, como estratégia de valorização de resíduos da indústria do curtume. A utilização de uma solução de gelatina comercial a 10 % em dimetilsulfóxido processada por wet spinning permitiu produzir fibras, cuja estabilidade estrutural foi melhorada pelo pós-tratamento térmico (30 °C, 200 mbar, 24 h), atuando como crosslinking físico. Ensaios de tração indicaram que as fibras suportaram, em média, uma força máxima de 106 cN, com
alongamento médio de 3,3 %. A caracterização das aparas de couro revelou valores de pH de 4,19, teor de humidade
de 8,96 %, gordura de 8,34 %, cinzas de 6,80 % e proteínas de 55,9 %. A análise de metais quantificou um teor de crómio de 1,44 % e de alumínio de 0,044 %, o que sugere que o material foi submetido a curtimento com sais de crómio, possivelmente seguido de recurtume leve com sais de alumínio. O colagénio foi extraído das aparas de couro por hidrólise alcalina, com hidróxido de sódio, 6 % (m/m), a 72 °C durante 6 horas, seguido de filtração, neutralização com ácido sulfúrico a 98 %, diálise e liofilização (-80 °C; 0,100 mbar), resultando num extrato proteico com 42,5 % de proteínas e 7,53 % de cinzas. O extrato proteico foi dissolvido nas condições otimizadas para a gelatina comercial. Contudo, ao contrário do que aconteceu com a gelatina, não foi possível a formação de fibras, a partir deste extrato. Com este trabalho ficou claro que a obtenção de fibras proteicas a partir de couro acabado é um objetivo complexo. Para atingir esse objetivo será necessário melhorar os processos de extração e purificação. A complexidade da matéria-prima (material polimérico reticulado com metais pesados e presença de vários produtos de acabamento) pode gerar
entraves significativos no que respeita à conversão do couro acabado em fibras proteicas.
The present work aimed to develop protein fibers using wet spinning. Initially, commercial gelatin was used to determine the ideal parameters for fiber production, such as temperature and solvent type. In a second phase, finished bovine leather trimmings were used to produce protein fibers, as a strategy to utilize tanning industry waste. The use of a 10 % commercial gelatin solution in dimethyl sulfoxide processed by wet spinning produced fibers whose structural stability was improved by post-heat treatment (30 °C, 200 mbar, 24 h), acting as physical crosslinking. Tensile tests indicated that the fibers withstood, on average, a maximum force of 106 cN, with an average elongation of 3.3 %. Characterization of the leather scraps revealed a pH of 4.19, moisture content of 8.96 %, fat content of 8.34 %, ash content of 6.80 %, and protein content of 55.9 %. Metal analysis quantified a chromium content of 1.44 % and an aluminum content of 0.044 %, suggesting that the material was tanned with chromium salts, possibly followed by light retanning with aluminum salts. Collagen was extracted from the leather scraps by alkaline hydrolysis with 6 % (m/m) sodium hydroxide at 72°C for 6 hours, followed by filtration, neutralization with 98 % sulfuric acid, dialysis, and freeze-drying (-80°C; 0.100 mbar), resulting in a protein extract with 42.5 % protein and 7.53 % ash. The protein extract was dissolved under conditions optimized for commercial gelatin. However, unlike what happened with gelatin, fiber formation from this extract was not possible. This work has made it clear that obtaining protein fibers from finished leather is a complex goal. Achieving this goal will require improved extraction and purification processes. The complexity of the raw material (polymer material cross-linked with heavy metals and the presence of various finishing products) can create significant obstacles to converting finished leather into protein fibers.
The present work aimed to develop protein fibers using wet spinning. Initially, commercial gelatin was used to determine the ideal parameters for fiber production, such as temperature and solvent type. In a second phase, finished bovine leather trimmings were used to produce protein fibers, as a strategy to utilize tanning industry waste. The use of a 10 % commercial gelatin solution in dimethyl sulfoxide processed by wet spinning produced fibers whose structural stability was improved by post-heat treatment (30 °C, 200 mbar, 24 h), acting as physical crosslinking. Tensile tests indicated that the fibers withstood, on average, a maximum force of 106 cN, with an average elongation of 3.3 %. Characterization of the leather scraps revealed a pH of 4.19, moisture content of 8.96 %, fat content of 8.34 %, ash content of 6.80 %, and protein content of 55.9 %. Metal analysis quantified a chromium content of 1.44 % and an aluminum content of 0.044 %, suggesting that the material was tanned with chromium salts, possibly followed by light retanning with aluminum salts. Collagen was extracted from the leather scraps by alkaline hydrolysis with 6 % (m/m) sodium hydroxide at 72°C for 6 hours, followed by filtration, neutralization with 98 % sulfuric acid, dialysis, and freeze-drying (-80°C; 0.100 mbar), resulting in a protein extract with 42.5 % protein and 7.53 % ash. The protein extract was dissolved under conditions optimized for commercial gelatin. However, unlike what happened with gelatin, fiber formation from this extract was not possible. This work has made it clear that obtaining protein fibers from finished leather is a complex goal. Achieving this goal will require improved extraction and purification processes. The complexity of the raw material (polymer material cross-linked with heavy metals and the presence of various finishing products) can create significant obstacles to converting finished leather into protein fibers.
Description
Keywords
Protein Fibers Collagen Leather Alkaline Extraction Gellatin Sustainability Wet Spinning Waste Recovery Fibras de proteína Colagénio Couro Extração alcalina Gelatina