SURFACE MODIFICATION OF POLYETHYLENE FIBER BY GRAFT-POLYMERIZATION

To improve the wettability and adhesion, graft polymerization of acryl amide (AAm) and glycidyl methacrylate (GMA) was performed onto the sur face of ultra-high modulus polyethylene (UHMPE) fiber pretreated with Ar plasma. Following the plasma treatment and the subsequent exposure to air to introduce peroxides onto the fiber surface, graft polymeriza tion onto the UHMPE fiber was allowed to proceed from the polymer pero xides either in deaerated monomer solution at an elevated temperature (degassing method), or in aerated monomer solution containing riboflav in at 30-degrees-C under UV irradiation (photoinduction method). The m onomer solution was prepared from water and dioxane for AAm and GMA, r espectively. After rigorous removal of homopolymers, surface analysis of the grafted fibers was performed with ATR-FTIR and XPS, which revea led that PAAm and PGMA chains were grafted in the surface region of fi bers. The grafting rate of PAAm by the photoinduction method was much higher than that by the degassing method when compared at the same con centration of the AAm solution. The amount of PGMA grafted was greatly affected by UV irradiation time, but depended on plasma treatment tim e to an insignificant extent if the treatment was carried out for long er than 30 s. Reaction of propylamine with the PGMA-grafted surface re sulted in the appearance of a nitrogen peak in the XPS spectrum, sugge sting the presence of epoxy groups on the surface of PGMA grafted fibe r. (C) 1994 John Wiley & Sons, Inc.