Abstract
Preparing of polypeptide fibers having the excellent characteristics of both poly(methyl glutamate) (PMG) and poly(glutamic acid) (PGA) fibers was examined, and the following results were obtained.
(1) By uniformly saponifying PMG fiber, a uniform (methyl glutamate-glutamic acid) copolymer fiber was obtained, and the water-sorptive capacity and the dyeability were improved without serious deterioration of mechanical properties. By surface saponifying PMG fiber, which yielded a continuous composite fiber of copolymer of surface part and PMG of core part, especially the wet strength and the wet modulus were much improved.
(2) The tensile strength of polypeptide fibers depended more on the content of β-form structure than on the degree of molecular orientation.
(3) The water vapor sorption of fiber was higher than that of membrane, because of the β-form structure of fiber.
(4) The water sorption process in the β-form structure may be described as follows: water molecules are sorbed on free polar groups of main chain at low relative vapor pressure, and hydrogen bonds between polar groups in the main chain are in some extent broken at the higher relative vapor pressure for water molecules to be absorbed on those parts.
