Modification of the reactive core-shell particles properties to prepare PBT/PC blends with higher toughness and stiffness

Abstract

Glycidyl methacrylate (GMA) functionalized methyl methacrylate-butadiene-styrene core-shell particles (PB-g-MSG) were prepared to toughen poly (butylene terephthalate) (PBT) and polycarbonate (PC) blends. T-dodecyl mercaptan (TDDM) was used to modify the grafting character of the core-shell particles. The addition of TDDM decreased the grafting degree, particles size and crosslinking degree of PB-g-MSG particles. At the same time, the free methyl methacrylate-co-styrene-co-glyceryl methacrylate copolymer (f-MSG) increased. The f-MSG reacted with PBT and suppressed the transesterification between PBT and PC. On the other hand, f-MSG promoted the crystallization of PBT by heterogeneous nucleation. When the TDDM content was lower than 0.76%, PB-g-MSG particles dispersed in the matrix uniformly, otherwise, agglomeration took place. The change of TDDM content in the PB-g-MSG particles influenced the toughening ability and tensile properties. When the TDDM content was 0.76%, the PBT/PC/PB-g-MSG blend showed the optimum impact toughness and yield strength, which are 908 J/m and 49.4Mpa. Fracture mechanism results indicated that cavitation induced shear yielding occurred in the PBT/PC/PB-g-MSG blend when no TDDM addition for the core-shell particles. With the addition of TDDM, the interfacial strength decreased between the PB-g-MSG core-shell particles and the matrix. So voids appeared due to debonding, which also could promote the shear yielding process.

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