Continuous surface modification process with ultraviolet/ozone for improving interfacial adhesion of poly(ethylene terephthalate)/epoxy composites

Abstract

This study proposed a continuous UV/ozone surface modification process for the production of polymeric fiber-reinforced polymer composite. A gas phase photoreactor using the conventional low-pressure mercury UV lamps and the economically made ozone generators were designed and constructed. Poly(ethylene terephthalate) (PET) fibers and epoxy resin were chosen as a reinforcement and a matrix, respectively. The synergistic effects of UV and various gas species (nitrogen, air, oxygen, air/ozone, and oxygen/ozone) exposure as well as the effects of exposure time, i.e., 2, 5, and 10 min, on the morphology and chemistry of PET-fiber surfaces were investigated by using a scanning electron microscope coupled with energy dispersive x-ray analysis (SEM/EDX). The tensile testing and analysis of fractography of the resulted composites were performed to evaluate the effectiveness of the process. The SEM/EDX results showed that the effects of the treatment were dependent on both the concentration of reactive species present in the gases and the exposure time. The PET fibers treated under UV/O2 + O3 exposure for 5 min yielded the resulting composite with the highest tensile strength value. Under this condition, the tensile strength of the composite can be increased up to 63% in comparison with that of the untreated PET fiber/epoxy composite. The results are of interest for application as an in-line surface modification for composite productions. POLYM. COMPOS., 27:484–490, 2006. © 2006 Society of Plastics Engineers