Molecular orientation and mechanophysical properties of cocoon filament

Abstract

Molecular orientation, crystallinity and mechanophysical properties of the cocoon filaments, of which size are varied by the juvenile hormone analogue or antijuvenoid were studied by means of X-ray diffraction birefringence measurement. Breaking strength and Young's modulus of the cocoon filament increased, which may be attributed to the increasing of the birefringence and molecular orientation, when the size of the cocoon filament decreased. Molecular orientation (f_x) of the cocoon filament increased up to the value (0.92) recorded for the cocoon filament possessing the ideal molecular orientation, when the shearing stress applied to a unit cross section of the cocoon filament increased. The value of birefringence of the ideal silk fiber whose molecular orientation increased up to the saturation value was 0.0550 by extraporating to be approximately denier 0. The evidence obtained from the X-ray diffraction indicated that the molecular orientation and crystallinity are dependent to the size of the cocoon filament.