How brittle-ductile transition (BDT) in uniaxial compression depends on the network structure affected by predeformation

Polystyrene of sufficiently high molecular weight is nevertheless brittle at room temperature upon tensile extension. However, the same brittle PS is actually ductile in uniaxial compression. Our recently proposed phenomenological molecular model¹ can not only explain this intriguing different from a molecular viewpoint but also anticipate how predeformation such as melt stretching shifts the BDT. Experiments are carried out to verify our theoretical predictions. Specifically, we apply melt stretching to alter the chain network structure and examine the effects of melt stretching in comparison to the predicted responses.
1. S. Q. Wang, S. W. Cheng, P. P. Lin and X. X. Li, "A phenomenological molecular model for brittle-ductile transition and yielding of polymer glasses", J. Chem. Phys. 141, 094905 (2014).