Finite Element Analysis of the Composite Fiber, Alpha Keratin

Abstract

The individual mechanical properties of each of the phases, microfibrils, and matrix in α-keratin fibers were analyzed in terms of a two-phase composite of microfibrils and matrix. The authors applied finite element techniques appropriate for composite micromechanics to the data available on the mechanical properties of various α- keratins with varying moisture contents. Despite some simplifying assumptions the result of the analysis was in general agreement with our present understanding of keratin structure. The results indicated the following: Absorption of water by the keratin structure has a pronounced weakening effect confined mainly to the matrix. Differences existing between different keratins were in the main due to variation of matrix properties produced by the presence of high glycine-tyrosine and high sulphur proteins, both of which increase the mechanical stiffness of the matrix. Data obtained for porcupine quill show that whereas the microfibrils can be considered as isotropic at all moisture contents of the keratin structure, the matrix must become highly anisotropic at saturated moisture contents.