Flow-induced Crystallization of a Long Chain Aliphatic Polyamide in Micro-Injection Moulding:
Coates Phil (1)*, Whiteside Ben (1), Tuinea-Bobe Cristina (1), Gao Yunyun (2), Dong Xia (2), Wang Lili (2), Liu Guoming (3), Wang Dujin (2)
(1) University of Bradford - W Yorks - UnitedKingdom, (2) Institute of Chemistry Chinese Academy of Sciences - Beijing - China, (3) Institute of Chemistry Chinese Academy of Sciences - B - China
The flow-induced crystallization structures of micro-injection moulded polyamide 1012 (PA1012), a kind of long chain aliphatic polyamides (LCPA) possessing intrinsic flexibility and strong intermolecular interaction simultaneously , was studied using a combination of synchrotron micro-focused wide angle X-ray scattering (μWAXS), small angle X-ray scattering (SAXS) and Fourier transform infrared micro-spectroscopy (μFTIR). An invertsed anisotropic crystallization morphology was characterized in two directions: perpendicular and parallel to the flow direction (FD). The rheology data demonstrated a novel anisotropic structure and formation mechanism for flow induced crystallisation, with distinct features both for PA1012 and for micro-injection moulding techniques used in this study. The combined analysis of the experimental results suggested a new vision of formation mechanism: the novel crystalline crystallization morphology was caused by the co-effects of the converging flow at the injection gate, the wall slip effect with strong-to-weak transition, and the fountain flow in the micro cavity.