Chemical modification of styrene/ethylene-buthylene/styrene copolymers

The chemical modification of two thermoplastic elastomer styrene/ethylene-b uthylene/styrene copolymers (SEBS) with diethylmaleate (DEM) as functionali zing agent was carried out in a corotating twin screw extruder and in an in ternal mixer. The residence time distribution of the extruder was studied d ue to its great influence on the grafting chemical reaction, the degree of functionalization, and the viscoelastic properties of the obtained modified polymers. The influence of copolymer melt viscosities, and DEM and initiat or concentration ratio on the grafting degrees was studied as well. In this case, an internal mixer was used. Optimal processing conditions were estab lished to obtain grafted polymers characterized by good processability and an absence of crosslinking. The grafting degree achieved in the internal mi xer was the same for both copolymers with different viscosities and it incr eased as the DEM and initiator concentrations and concentration ratios were increased.