Tensile behavior and impact strength of poly(butylene terephthlate) (PBT)/styrene-ethylene-butylene-styrene (SEBS) copolymer blends were studied at SEBS volume fraction 0-0.38. Tensile modulus and strength decreased, whereas breaking elongation increased with SEBS content. Predictive models are used to evaluate the tensile properties. Strength properties were dependent on the crystallinity of PBT and phase adhesion. The normalized notched Izod impact strength increased with the SEBS content; at F d ¼ 0.38, the impact strength enhanced to five times that of PBT. Scanning electron microscopy was used to examine phase morphology. Concentration and interparticle distance of the dispersed phase influenced impact toughening. In the presence of maleic anhydride-grafted SEBS (SEBS-g-MAH), the tensile modulus and strength decreased significantly, while normalized relative notched Izod impact strength enhanced to 7.5 times because of enhanced interphase adhesion.
Melt rheological properties of PBT/SEBS and PBT/SEBS/SEBS-g-MA blends at SEBS volume fraction (U d ) 5 0.00-0.38 were studied at 240 C, 250 C and 260 C using a capillary rheometer. The compatibilizer SEBS-g-MA addition resulted in significant reduction in the dynamic interfacial tension which in turn led to increased phase adhesion. The power law exponent n decreased with increasing U d and increasing temperature for both the compatiblized and uncompatiblized blends. The consistency index of PBT/SEBS increased with increasing U d but were smaller than those of PBT/SEBS/SEBS-g-MA blends. Melt elasticity such as die swell and first normal stress difference increased with U d . Variations of first normal stress coefficient function (w 1 ), recoverable shear strain (c R ), relaxation time (k), and shear compliance (J c ) values versus shear rate were analyzed.
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