Partially Carboxymethylated Feather Keratins. 2. Thermal and Mechanical Properties of Films
- 16 December 2000
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of Agricultural and Food Chemistry
- Vol. 49 (1), 221-230
- https://doi.org/10.1021/jf0004154
Abstract
Free cysteine thiol groups of keratin extracted from chicken feathers were partially carboxymethylated with iodoacetic acid (25−76% cysteine modification). Stable dispersions were used for the preparation of films by solution casting. Glycerol was used as a plasticizer (0.05−0.47 g/g of keratin), and films were stored at a constant relative humidity (20, 30, 50, 70, or 90%). The degree of crystallinity in the films was higher when more cysteine residues were carboxymethylated. The films displayed an optimum in mechanical properties at ∼50% cysteine carboxymethylation. The tensile strength at this optimum was 25 MPa, the E modulus, 350 MPa, and the elongation at break, 50%. Probably, this optimum was the result of both a decreasing amount of disulfide bonds and an increasing degree of crystallinity for higher degrees of cysteine modification. The influences of a higher amount of glycerol and of different storage conditions on the mechanical properties of films from keratin with a defined degree of cysteine modification were also investigated. Keywords: Feather; keratins; films; chemical modification; thermal properties; mechanical propertiesThis publication has 17 references indexed in Scilit:
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