Journal of Elastomers & Plastics

Polypropylene (PP) composites were prepared by compounding PP with untreated, as well as treated barium sulphate. Barium sulphate filler had been treated with different surface modifiers such as sodium dodecyl benzene sulphonate (SDBS), polyoxyethylene sorbitan monooleate (Tween 60) and oleic acid. The mechanical properties of the prepared composites were evaluated. It was found that the filler treatment with SDBS enhanced the tensile yield strength and hardness of the resulting composites and also the elongation at rupture for most of the composites. Tween 60 and oleic acid as treating agents for the filler had the same effect on the tensile yield strength, while increasing their amounts on the surface decreased the elongation properties of the composites.

This work presents a comparative study of the morphology and structure-related properties of thermoplastic elastomer blends based on SEBS-PP-oil and dynamically vulcanized EPDM-PP-oil prepared under identical conditions. Compositions of each blend type with three different SEBS-PP and EPDM-PP ratios by weight were made in a co-rotating twin-screw extruder and a Brabender internal mixer. A comparative study of different electron microscopic techniques for studying the morphology of these oil-extended blends is reported. Morphological characterization using different microscopic techniques showed a co-continuous morphology for the SEBS-PP-oil blends and droplet-matrix morphology for the thermoplastic vulcanizate (TPV) blends. The particle size distribution of the EPDM-phases in the TPVs prepared in the twin-screw extruder was wider than for the Brabender mixer. No difference in the morphology was observed for the SEBS-PP-oil blends prepared in the twin-screw extruder and Brabender, except for the blend with the highest PP content. The elongation-at-break values were significantly higher for the SEBS-PP-oil blends as compared to the TPV blends. The gel content of the TPVs was the main factor determining the stress-strain properties, as influenced by the preparation method. Also the crystallinity of the PP-phase for both SEBS-PP-oil and TPV blends was investigated and, although being dependent on the preparation method for the SEBS-PP-oil blends, did not reflect in the stress-strain properties.

A preliminary study on the influences of the nylon-1010 powder, as a new candidate for fillers, on the cellular structure and mechanical properties of rigid polyurethane foam (RPUF) is presented. By observation of the scanning electron micrographs, it was found that the cells of the nylon powder-filled RPUF were mainly spheroid. When the nylon content was 5 wt%, the nylon particles were dispersed rather uniformly, whereas when the nylon content exceeded 10 wt%, the particles were hard to disperse in the matrix, and formed agglomerates. The compressive and tensile strengths of the unfilled RPUF exhibited a power-law dependence with respect to density of the foam: ^{* 1}/4 (^*) n. The measured tensile modulus of the unfilled RPUF was described well by a simple geometric model. The compressive modulus was also found to follow a power-law behavior with respect to foam density. Addition of 5 wt% nylon powder increased the tensile modulus and strength, but without a change in the density dependence. It can be found that the tensile modulus of the foam with 5 and 10 wt% nylon powder fit the predicted model well, but, at the filler concentration of 15 and 20 wt%, the power-law behavior did not work.

A viscoelastic constitutive model of cord-rubber composite is established by introduction of strain energy density function; a new failure criterion is also proposed in terms of different failure modes of unidirectional ply of rubber composite. They are validated by biaxial tensile experimental data of nylon-6 cord-rubber composite. Results show that the proposed large deformation and viscoelastic constitutive model is an effective model for cord-rubber composite and the new failure criterion can be used to predict tensile failure of ply of cord-rubber composite.

The flow properties during capillary extrusion of quasi-nano-meter calcium carbonate-filled acrylonitrile-butadiene-styrene copolymer (ABS) composite and an unfilled ABS resin melts were measured by using a Rosand capillary rheometer to identify the effects of test operation conditions on the rheological behavior of the sample melts. The experiments were conducted under the following test conditions: temperatures varied from 200 to 240 C and shear rate range of 10-10⁴ s 1. The results showed that the shear flow for both the filled ABS and the unfilled ABS resin melts did not obey strictly the power law at high shear rates, and the entry pressure drop (P_en) and the extension stress (e) in entry flow increased nonlinearly, while the melt shear viscosity (s) and extension viscosity (e) decreased with the increasing wall shear stress (w) at constant test temperature. The dependence of the melt shear viscosity on the test temperature was approximately consistent with the Arrhenius expression at fixed w. At the same test conditions, the values of s, e, and w for the filled ABS resin were higher than those for the unfilled ABS, while the values of e and P_en for the former were lower than those for the latter.