Effect of irradiation on interfacial interaction and structure formation in filled PTFE composites

Abstract

The supramolecular structure and tribological properties of filled polytetrafluoroethylene composites irradiated above the melting point of the crystalline phase of the polymer component and the phase transitions in them are investigated. In unirradiated composites, phase separation is observed, that is, the separation of the filler from the polymer matrix. The supramolecular structure of the polymer component does not depend on the nature and concentration of the filler, and it is characterized by the formation of lamellae during sintering and subsequent crystallization. Radiation exposure leads to the disappearance of the phase separation and the formation of axiolites with the radial orientation of fibrils, in the center of which the filler particles are located. Changes in the structure are explained by an increase in interfacial interactions through the radiation grafting of macromolecules (and low-molecular-weight products) to the surface of the filler particles. The linear wear rate of irradiated composites is 50 times lower relative to the unirradiated samples because of the transition from the delamination to abrasive wear mechanism.