Macromolecular structural evolution of polyimide chains during large-ratio uniaxial fiber orientation process revealed by molecular dynamics simulation

摘要

Pyromellitic dianhydride (PMDA)/4,4'-oxidianiline (ODA) polyimide (PI) orientation models with different draft ratios were established to reveal the macromolecular structural evolution of PI chains during large-ratio uniaxial fiber orientation process. The high consistency between experimental data and modelling results, in terms of mechanical properties and XRD patterns, demonstrates the rationality of the orientation models. The simulation results indicated that the PI chains became stretched from entanglement and arranged along the draft direction in the fiber drafting process, and chain orientation observed in PMDA/ODA-based PI fibers during drafting was mainly caused by the change of C-C-O-C torsion distribution in the ODA units.