Rapid Melt Crystallization of Bisphenol-A Polycarbonate Jointly Induced by Pressure and Flow
Xixi Zhang, Shu‐Gui Yang, Gan‐Ji Zhong, Jun Lei, Dong Liu, Guangai Sun, Jia‐Zhuang Xu, Zhong‐Ming Li
Abstract
Bisphenol-A polycarbonate (PC) is an intrinsically crystallizable polymer. Its industrial parts, however, invariably remain in an amorphous state due to its extremely slow crystallization kinetics. In the current study, we reported rapid melt crystallization of bulk PC jointly induced by pressure and shear flow. The crystallinity of pure bulk PC reached up to ∼25% when crystallized at 100 MPa and 42.8 s–1 for only 60 min, ca. 500 times faster than quiescent melt crystallization under ordinary pressure. In consideration of no crystallization by applying pressure or shear flow alone, a synergistic effect of pressure and flow on promoting crystallization kinetics of PC clearly existed. The spinodal decomposition induced by pressure and flow activated the conformation ordering prior to nucleation, and furthermore, the flow-induced chain orientation facilitated nucleation via reducing the energy barrier. The critical shear rate for nucleation was reduced effectively by increasing the applied pressure. A formula of the modified specific work of flow was proposed to quantify the contribution of pressure and flow to the rapid crystallization of PC. There existed a critical specific work of flow, wc(T,P) = (3.9 ± 0.3) × 108 J·m–3, only above which the PC could crystallize. The findings in this work may revolutionize our understanding of the crystallization of PC and other similar polymers with rigid chains.