Silane-modified poly(ethylene-co-vinyl acetate): Influence of comonomers on peroxide-initiated vinylsilane crafting

摘要

Functionalization of poly(ethylene-co-vinyl acetate) (EVA) with vinyltri-ethoxysilane (VTEOS) has been carried out by a free-radical melt-grafting procedure in the presence of added comonomers. The influence of comonomers on silane graft yield and crosslink density has been assessed. Experiments were performed on master-batches of EVA, VTEOS (5 wt %), peroxide initiator (L-231, 0.05 wt %), and comonomer (0-1 comonomer : VTEOS mole ratio) prepared at 90 degrees C. Melt-grafting experiments were carried out at 145 degrees C in an oscillating disk rheometer (ODR), which measured crosslink density during the grafting process. Silane graft yields were determined by proton NMR spectroscopy. Comonomers evaluated were maleic anhydride (MAn), 1-vinyl-2-pyrrolidone (VP), and 1-dodecene (DD). At the comonomer ratios examined, MAn suppressed both silane grafting and peroxide-initiated crosslinking. Both VP and DD, however, exhibited greater selectivity in suppressing crosslinking than silane grafting; optimum performance was found at a comonomer : vinylsilane mole ratio of 0.2. None of the comonomers studied enhanced the level of silane grafting. (C) 2000 John Wiley & Sons, Inc. [References: 12]