SYNOPSISThis article reports the influence of oscillating pressure on the mechanical performance of general-grade high-density polyethylene (HDPE). The tensile strength of 93 MPa and the Young's modulus of 5 GPa were obtained by an oscillating packing technique. The great improvement of the mechanical properties of HDPE specimens is due to the existence of the shish-kebab crystalline structure, the orientation of the molecular chains along the flow direction, and the more perfect crystallites.

Poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 (PPO/PA6) blends were reactively compatibilized by maleic anhydride (MA) grafted PPO (PPO‐g‐MA) and reinforced by short glass fibers (SGF) via melt extrusion. An observation of the SGF‐polymer interface by scanning electronic microscope (SEM) together with etching techniques indicated that the PPO‐g‐MA played a decisive role in the adhesion of polymers to SGF. The rheological behavior was investigated by capillary rheometer, and the addition of PPO‐g‐MA, and SGF could increase the viscosity of the PPO/PA6 blends. The analysis of fiber orientation and distribution in the PPO/PA6/SGF composites showed PPO‐g‐MA favored to the random dispersion of SGF. The statistic analysis of SGF length showed that PPO‐g‐MA was helpful to maintain the fiber length during melt‐processing. For the composites at a given SGF content of 30 wt %, the addition of PPO‐g‐MA increased the tensile strength from 59.4 MPa to 97.1 MPa and increased SGF efficiency factor from 0.028 to 0.132. The experimental data were consistent with the theoretical predictions of the extension of Kelly‐Tyson model for tensile strength. The fracture toughness of the composites was investigated by single edge notch three‐point bending test. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2188–2197, 2009

Poly(2,6-dimethyl-1,4-phenylene oxide)/ polyamide 6 (PPO/PA6 30/70) blends were impact modified by addition of three kinds of maleated polystyrene-based copolymers, i.e., maleated styrene-ethylene-butylene-styrene copolymer (SEBS-g-MA), maleated methyl methacrylate-butadiene-styrene copolymer (MBS-g-MA), and maleated acrylonitrile-butadiene-styrene copolymer (ABS-g-MA). The mechanical properties, morphology and rheological behavior of the impact modified PPO/PA6 blends were investigated. The selective location of the maleated copolymers in one phase or at interface accounted for the different toughening effects of the maleated copolymer, which is closely related to their molecular structure and composition. SEBS-g-MA was uniformly dispersed in PPO phase and greatly toughened PPO/PA6 blends even at low temperature. MBS-g-MA particles were mainly dispersed in the PA6 phase and around the PPO phase, resulting in a significant enhancement of the notched Izod impact strength of PPO/PA6 blends from 45 J/m to 281 J/m at the MBS-g-MA content of 20 phr. In comparison, the ABS-g-MA was mainly dispersed in PA6 phase without much influencing the original mechanical properties of the PPO/PA6 blend. The different molecule structure and selective location of the maleated copolymers in the blends were reflected by the change of rheological behavior as well.

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Poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 6 (PPO/PA6) blends were reactively compatibilized by maleic anhydride (MA) grafted PPO (PPO-g-MA) and toughened by MA grafted styrene-ethylene-butadiene-styrene block copolymer (SEBS) (SEBS-g-MA) via melt extrusion. The compatibilizing effect of PPO-g-MA on the PPO/PA6 blends was studied by using scanning electronic microscopy, differential scanning calorimetry and mechanical properties tests. The notched impact strength of PPO-g-MA/PPO/PA6/SEBS-g-MA blends increased with increasing SEBS-g-MA content, leading to blends having super-tough behaviour. The fracture behaviour of the PPO/PA6 blends was studied using a modified essential work of fracture model (EWF), which showed that plastic deformation related to SEBS-g-MA was the crucial factor for the toughening.

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