EFFECT OF THE INTERPHASE SURFACE-ENERGY ON THE STRUCTURE OF CRAZED POLYMERS

Structural changes in the classical and intercrystallite (delocalized) crazes were studied by X-ray diffraction in PP samples upon drawing i n n-propanol and replacing the initial medium by other liquid or air. Formulas are derived for calculating (from small-angle X-ray scatterin g data) the volume fraction of crazes, fibril concentration, and other parameters of crazed systems upon a partial structural collapse leadi ng to a change in the sample cross-section. It is demonstrated that fi brils occurring in the crazes of PP represent an oriented polymer with a high degree of crystallinity in the case of both classical and inte rcrystallite crazing. The length of fibrils affects a change in the sp ecific surface S upon the ''isometric'' medium substitution in the cra zes of various types, but the limiting values of parameters of the mic roporous structure are determined by the interphase surface energy gam ma. The rule gamma S = const exhibits a quite universal character and is valid for the medium substitution in crazed polymers with different chemical compositions, structures, and types of crazing.