Abstract
AbstractBACKGROUNDCoarse low grade wool holds a share of more than 40% of the worldwide production of 1.2 million tons per year. Wool hair with a diameter above 32.5 μm and recycled wool waste represent an important source of high quality keratin. An efficient and simple shaping procedure to form all‐keratin composites could open a new approach to utilise wool keratin for production of sustainable and biodegradable all‐keratin composite.RESULTSIn this work the dissolution and regeneration of wool keratin was studied using a concentrated solution of calcium chloride–water–ethanol as solvent and thioglycolate as reducing agent to open disulphide bonds. Up to 70% of the wool keratin dissolved in the solvent at pH 7, 60 °C. After dilution with water a share of 80% of the total keratin could be obtained as regenerated composite structure while 20% of the protein remains in solution. Based on the model studies, all‐keratin composites were prepared by impregnation of wool with solvent followed by thermal consolidation in a heated press at 60 °C and 2.2–3.3 bar pressure.CONCLUSIONSThe new method for production of all‐keratin composites permits production of a protein‐based bio‐composite, which opens new applications for low value coarse wool and recycled wool waste. By use of cheap chemicals and thermal consolidation in standard equipment scale‐up of the technology is expected to be straightforward and commercially feasible, leading to a bio‐based and biodegradable composite material. © 2019 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Highlights
The worldwide annual production of wool is in the region of 1.2 million tons.[1,2] Dependent on the breed, the diameter of the wool varies from highly valuable superfine merino wool (< 16 μm) to low value coarse hair (> 32.5 μm)
Coarse wool and wool waste could serve as a keratin source for bio-composite production.[4,5]
In this article we report to our knowledge for the first time the use of a synergistic mixture of CaCl2 –water–ethanol and thioglycolate (CWET) for dissolution of wool keratin and direct formation of an all-keratin composite through one-step thermal consolidation.[37]
Summary
The worldwide annual production of wool is in the region of 1.2 million tons.[1,2] Dependent on the breed, the diameter of the wool varies from highly valuable superfine merino wool (< 16 μm) to low value coarse hair (> 32.5 μm). Limited applications exist for coarse wool, which for example can be hydrolysed and used as a nitrogen-fertiliser.[3] Coarse wool and wool waste could serve as a keratin source for bio-composite production.[4,5]. Coarse low grade wool holds a share of more than 40% of the worldwide production of 1.2 million tons per year. An efficient and simple shaping procedure to form all-keratin composites could open a new approach to utilise wool keratin for production of sustainable and biodegradable all-keratin composite
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