Strain-induced molecular orientation and crystallization in natural and synthetic rubbers under uniaxial deformation by in-situ synchrotron X-ray study

摘要

In-situ synchrotron wide-angle X-ray diffraction (WAXD) studies and simultaneous measurements of stresses and strains during uniaxial stretching of various vulcanized rubbers were applied (at room temperatures and at 0 degC) to reveal their strain-induced molecular orientation and crystallization relationships.Rubbers evaluated include natural rubber (NR),synthetic poly-isoprene rubber (IR),poly-cis-1,4-butadiene rubber (BR) and butyl rubber (IIR),Some universal features were observed in these systems.(1) At high strains (>5.0),the majority of the chains (up to 50 approx 75%) in natural and synthetic rubbers remained in the un-oriented amorphous state with only a small amount of crystalline fraction formed (10-20%).