The effect of the oxygen-plasma treatment of UHMWPE fiber on the transverse properties of UHMWPE-fiber/vinylester composites

The effects of oxygen-plasma treatment of ultra-high-modulus polyethylene ( UHMPE) fiber on the transverse properties of the UHMPE fiber/vinylester com posites have been investigated. The UHMPE fiber/vinylester unidirectional ( UD) laminates were prepared with untreated and oxygen-plasma-treated UHMPE fiber. The oxygen-plasma treatment of the UHMPE fiber increases the transve rse tensile strength and failure strain of UHMPE-fiber/vinylester composite s and changes the failure initiation site from the interface to the interio r of the UHMPE fiber. The oxygen-plasma treatment of the UHMPE fiber introd uced micro-pits on the fiber surface; these micro-pits improve the interfac ial adhesion in UHMPE fiber/vinylester composites through the mechanical in terlocking between the micro-pits and the vinylester resin. Finite-element (FE) modeling was performed to investigate the effect of the micro-pits on stress transfer in the UHMPE-fiber/vinylester composite. The micro-pits are known to increase the stress transfer from the vinylester resin to the UHM PE fiber and this increased stress transfer is correlated with the improved transverse properties and the transition of the failure initiation site af ter oxygen plasma treatment. (C) 1999 Elsevier Science Ltd. All rights rese rved.