Modification of PTFE nanopowder by controlled electron beam irradiation: A useful approach for the development of PTFE coupled EPDM compounds

Abstract

Low-temperature reactive mixing of controlled electron beam modified Polytetrafluoroethylene (PTFE) nanopowder with Ethylene-Propylene-Diene-Monomer (EPDM) rubber produced PTFE coupled EPDM rubber com- pounds with desired physical properties. The radiation-induced chemical alterations in PTFE nanopowder, determined by electron spin resonance (ESR) and Fourier transform infrared (FTIR) spectroscopy, showed increasing concentration of radicals and carboxylic groups (-COOH) with increasing irradiation dose. The morphological variations of the PTFE nanopowder including its decreasing mean agglomerate size with the absorbed dose was investigated by particle size and scanning electron microscopy (SEM) analysis. With increasing absorbed dose the wettability of the modified PTFE nanopowder determined by contact angle method increased in accordance with the (-COOH) concentration. Transmission electron microscopy (TEM) showed that modified PTFE nanopowder is obviously enwrapped by EPDM. This leads to a characteristic compatible interphase around the modified PTFE. Crystallization studies by differential scanning calorimetry (DSC) also revealed the existence of a compatible interphase in the modified PTFE coupled EPDM.