Dual monomer grafting of styrene and maleic anhydride onto model hydrocarbon substrates

Styrene and maleic anhydride (MAn) were successfully grafted, alone and sim ultaneously, onto various model hydrocarbon substrates at 180 degrees C wit h 2,5-dimethyl-2,5-di-(t-butyl peroxy)hexane (L101) as a free-radical initi ator. Dodecane, 1-dodecene, and 2,6,10,14-tetramethyIpentadecane were selec ted as model compounds to investigate the effects of terminal unsaturation and branching on grafting and crosslinking. These compounds were chosen to mimic the aforementioned microstructural characteristics that are commonly observed in polyethylene. The results demonstrate that terminal unsaturatio n increases the amount of crosslinked material in the presence of L101. Wit h respect to grafting, for the single monomer systems, MAn prefers to graft as single saturated units, whereas styrene prefers to graft as long chains of polystyrene oligomers. However, when both monomers are grafted simultan eously, graft yields are drastically reduced because of a propensity for th e two monomers to form a styrene-maleic anhydride copolymer. (C) 2000 John Wiley & Sons, Inc.