Toughening modification of polycarbonate/poly(butylene terephthalate) blends achieved by simultaneous addition of elastomer particles and carbon nanotubes

Small quantities of maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MAH) copolymer and carbon nanotubes (CNTs) were introduced into polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends. The results demonstrated that simultaneously adding SEBS-g-MAH and CNTs greatly enhanced the fracture toughness of the samples and the impact strength increased with increasing CNT content. The morphologies, the dispersion of CNTs, the relaxation behaviors and the crystallization behaviors of samples were systematically investigated. SEBS-g-MAH formed the dispersed particles in the system. The particle diameter was decreased in the blend composites. CNTs exhibited homogeneous dispersion in the blend composites and they also formed a percolated network structure at relatively high content. The transesterification between PC and PBT components was suppressed by SEBS-g-MAH, and the crystallization ability of the PBT component was greatly enhanced. The toughening mechanisms were mainly related to the suppressed transesterification, the decreased elastomer particle size, and the formation of a CNT network structure.