In Situ SAXS-WAXS Temperature Evolution Study of the Nanostructure of Self-Reinforced Ultrahigh Molecular Weight Polyethylene

Abstract

Ultrahigh molecular weight polyethylene (UHMWPE) is a thermoplastic high-performance polymer, which is in high demand in biomedicine, ship and machine building, production of anthropomorphic robots and smart prostheses. Highly oriented UHMWPE fibers possess record specific strength and may be used for the fabrication of self-reinforced PE-PE composites (SRPECs). The temperature evolution study of the small-angle X-ray scattering (SAXS) signature of the supramolecular structure of UHMWPE can help reveal their important role in the mechanism of the shape memory effect in SRPECs. The laboratory XEUSS 3.0 SAXS-WAXS beamline was used for in situ studies of the nanostructure parameters in unidirectional SRPEC. In particular, the radius of gyration and the dimensionality factor were derived from 2D SAXS patterns using several fitting algorithms. These parameters change significantly in the temperature ranges corresponding to the initiation of the shape memory effect and melting. The relationship between the material anisotropy and 2D SAXS patterns is discussed in the context of the supramolecular structure evolution.