Supertough poly(butylene terephthalate) (PBT) blends were prepared by melting with poly(ethyleneoctene) (POE) and glycidyl methacrylate grafted POE (POEg-GMA), and the toughening mechanism was systematically analyzed. Scanning electron microscopy (SEM) and rheological measurements identified that POE-g-GMA effectively improved the interaction between PBT and elastomer. The compatibility between phases improved gradually, while the notched impact strength increased at first and then decreased with the increase of POE-g-GMA content. The blends containing 10 wt % POE-g-GMA showed the highest impact strength, which was 18.0-fold compared to that of neat PBT. The study of the toughening mechanism indicated that a suitable compatibility was significant for obtaining supertough PBT blends because the good elastomers dispersion and suitable interfacial adhesion can be obtained simultaneously. The weak interface and the large particle size led to unstable crack propagation, while too strong interfacial adhesion prevented interface debonding and arrested matrix shear yielding. Microvoiding generated by both the debonding and internal cavitation of elastomers followed by matrix shear yielding was the main toughening mechanism in toughened PBT blends.

This work aimed at preparing supertough PA6 blends with only a small amount of elastomer. The PA6/SEBS-g-MA/PP blends were obtained by melt extrusion, in which the core−shell particles (PP as core and SEBS-g-MA as shell) could be formed in situ in PA6 matrix. The morphology of PA6 blends was explained by both the thermodynamic factor (interfacial tension and spreading coefficient) and the kinetic factor (viscosity ratio). By adjusting the loading of PP and SEBS-g-MA, the core−shell particles with suitable size could be obtained, and the notched impact strength of the PA6 blends could be significantly improved. The effects of the loading of PP and SEBS-g-MA on tensile properties were also studied. Consequently, PA6 blends with high tensile strength and excellent impact strength could be obtained by loading only a small amount of SEBS-g-MA.

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