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Polyphenylene sulfide (PPS)/multiwalled carbon nanotube (MWCNT) composites were prepared by melt blending and injection molding. The nonisothermal crystallization behavior, morphology, and mechanical properties of the nanocomposites were systematically investigated as a function of MWCNT content. For nonisothermal process, the presence of MWCNTs possesses both acceleration and retardation effect on the crystallization of PPS without affecting the ultimate degree of crystallinity. Due to the interfacial interaction between MWCNTs and PPS, the MWCNTs can be uniformly dispersed in PPS. The interfacial crystallization of PPS on the surface of nanotubes was observed by scanning electron microscopy and transmission electron microscopy. A reinforcing effect of MWCNTs on the mechanical properties of PPS is found, which is considered to be relevant with the uniformly dispersed MWCNTs and the interfacial crystallization.

Purpose This paper aims to research the influence of pressure, friction factors, roughness and actuating speed to the mixed lubrication models of outstroke and instroke. Design/methodology/approach Mixed lubrication model is solved by finite volume method, which consists of coupled fluid mechanics, deformation mechanics and contact mechanics analyses. The influence of friction factor on the finite element model is also considered. Then, contact pressure, film thickness, friction and leakage have been studied. Findings It was found that the amount of leakage is sensitive to the film thickness. The larger the film thickness is, the greater the influence received from the friction factor, however, the effect of oil film on the friction is negligible. The friction is determined mainly by the contact pressure. The trend of friction and leakage influenced by actuating velocity and roughness is also obtained. Originality/value The influence of friction factor on the finite element model is considered. This can make the calculation more accurate.

The effective thermal conductivity behavior of vulcanized perfluoromethyl vinyl ether (PMVE) rubber filled with various inorganic fillers was investigated and analyzed with thermal conductivity models. Experimental results showed that there was no significant improvement in the thermal conductivity of PMVE rubber if the intrinsic thermal conductivity of the fillers was greater than 100 times that of the rubber matrix, and this agreed with the prediction of Maxwell's equation. The thermal conductivity of PMVE rubber filled with larger size silicon carbide (SiC) particles was greater than that of PMVE filled with smaller size SiC because of the lower interfacial thermal resistance, and there existed a transition filler loading at about 60 vol %. It was also found that flocculent graphite was the most effective thermally conductive filler among the fillers studied. A modified form of Agari's equation with a parameter independent on the units used was proposed.

Methyl Phenyl and diphenyl silicone rubbers were synthesized from octamethyl cyclotetrasiloxane (D4), methylphenyl cyclosiloxane, octaphenyl cyclotetrasiloxane, etc. Compared with the commercial methylvinyl silicone rubber, the high and low temperature resistances of methyl vinyl silicone rubber were studied in this paper. The results showed that the introduction of phenyl groups can improve the thermal properties of silicone rubber, and the thermal stability of diphenyl silicone rubber is better than that of methyl phenyl silicone rubber. But there is little difference of mechanical properties in high temperature environment for three silicone rubber. DMTA analysis showed that there were still a small amount of crystals in diphenyl silicone rubber, while methylphenyl silicone rubber was amorphous rubber. The mechanical properties at low temperature indicated that the tensile strength of diphenyl silicone rubber was 4.1Mpa higher than that of methylphenyl silicone rubber at -70 °C due to the existence of low-temperature crystallization.

The thermal stability of high-temperature vulcanized silicone rubber with stannic oxide as a heat stabilizer was investigated by heat aging at 300°C ϫ 24 h in air. It was discovered that Sn ϩ4 is reduced to Sn 0 during vulcanization and during heat aging in air by X-ray photoelectron spectroscopy (XPS). EXPERIMENTALXPS analyses were carried out in a Perkin-Elmer PHI-1600 X-ray photoelectron spectrometer in a vacuum of 10 Ϫ8 Pa. For each specimen, a survey spectrum was recorded, together with high-resolution spectra of the region of interest (Sn3d5/2).

ABSTRACT:The thermal stability of high-temperature vulcanized silicone rubber with stannic oxide as a heat stabilizer was investigated by heat aging at 300°C ϫ 24 h in air. It was discovered that Sn ϩ4 is reduced to Sn 0 during vulcanization and during heat aging in air by X-ray photoelectron spectroscopy (XPS).