A high degree of crystallinity increases the tendency for environmental stress cracking.
Explain why.
Answers
Environmental stress cracking (ESC) of acrylonitrile-butadiene-styrene (ABS) copolymer caused by two kinds of non-ionic surfactants was studied by edge crack tension (ECT) tests. The dependence of the ESC on temperature and on the kind of surfactant was investigated. The fracture surfaces were investigated by a scanning electron microscope (SEM). It was found that when the temperature was low, the crack propagated by ESC and successive arrest of crack propagation which was caused by the change of morphology in large area at the crack tip. It was also found that when the temperature was high, the rise of temperature had a different effect on each surfactant. In that case, the penetration of the surfactant into the specimen was active, and the crack propagation behavior was almost the same as that at low temperature. On the other hand, if the penetration of the surfactant into the specimen was not so active, the crack propagated mainly by ESC.