Toughening of syndiotactic polystyrene and poly(2,6-dimethyl-1,4-diphenylene oxide) blends. I. Influence of mixing protocol and blend conditions

Abstract

It is well known that brittle polymers can be considerably toughened by the incorporation of miscible amorphous polymers or a thermoplastic elastomer. The effect of rubber toughening was studied via reactive extrusion to investigate the fracture mechanism and morphology controls of syndiotactic polystyrene (SPS)/poly(2,6-dimethyl-1,4-diphenylene oxide) (PPO) blends. Successful rubber toughening was achieved in compatibilization using reactive extrusion. The reactive polystyrene (RPS) as a compatibilizer and styrene-ethylene/butylene-styrene block copolymer (SEBS) as an impact modifier were used in an extrusion experiment. The impact strength was highly dependent on the blending condition and the composition. The best result was obtained by 2-step mixing; the first mixing of PPO with RPS (1.0 phr oxazoline content) and functionalized SEBS (f-SEBS, 0.4 phr maleic anhydride content) then followed with SPS mixing. Increase in RPS level gave rubber particle size reduction due to the reactions at the interfaces among polymer phases, as demonstrated by the decreased tan δ value. The storage modulus (E′) of SPS/PPO blends was decreased with increasing PPO content.