Poly(ethylene-co-butylene)-b-(styrene-ran-maleic anhydride)2 Compatibilizers via Nitroxide Mediated Radical Polymerization

Telechelic poly(ethylene-ran-butylene) initiator terminated with [tert-butyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino] nitroxide groups (PEB-(SG1)(2)) was used to initiate the controlled radical copolymerization of maleic anhydride (MA) and styrene (ST). The ST/MA copolymerizations were performed in 1,4-dioxane at 110 degrees C and resulted in PEB-b-P(ST-ran-MA)(2) triblock copolymers with relatively narrow molecular weight distributions ((M) over bar (m)/(M) over bar (n) approximate to 1.5). Gel permeation chromatography (GPC) indicated that the initiator used was approximate to 93% efficient. The resulting copolymers were then blended as 20 wt.% dispersions in nylon 6 (PA6) at 230 degrees C. With as little as 10 mol.% of MA in the feed to make the PEB-b-P(ST-ran-MA)(2), blends were deemed dynamically compatibilized based on the reduced particle size. All of the PEB-b-P(ST-ran-MA)(2)/PA6 blends resulted in a minor phase particle size (D) over bar (VS) = 0.1 mu m while the PEB-b-P(ST)/PA6 blend had (D) over bar (VS) = 1.15 mu m (i.e. no MA in the copolymer). Tensile testing revealed yield stresses and strains decreased steadily from pure PA6 to non-reactive PEB-b-P(ST)(2)/PA6 to PEB-b-P(STran-MA)(2)/PA6 However, no difference in tensile properties was observed between PEB-b-P(ST-ran-MA)(2)/PA6 samples mode from PEB-b-P(ST-ran-MA)(2) copolymer of varying MA content.