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

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 inve stigate the fracture mechanism and morphology controls of syndiotactic poly styrene (SPS)/poly(2,6-dimethyl-1,4diphenylene oxide) (PPO) blends. Success ful rubber toughening was achieved in compatibilization using reactive extr usion. The reactive polystyrene (RPS) as a compatibilizer and styrene-ethyl ene/butylene-styrene block copolymer (SEBS) as an impact modifier were used in an extrusion experiment. The impact strength was highly dependent on th e 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)a nd functionalized SEES (f-SEBS, 0.4phr maleic anhydride content) then follo wed with SPS mixing, increase in RPS level gave rubber particle size reduct ion due to the reactions at the interfaces among polymer phases, as demonst rated by the decreased tan delta value. The storage modulus (E') of SPS/PPO blends was decreased with increasing PPO content.