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Styrene modified natural rubber (SNR) is a modified rubber that can work as an impact modifier and compatibilizer for polystyrene (PS) matrix. The effect of different vulcanization techniques based on the sulfur vulcanization system has been investigated to produce SNR vulcanizates for natural rubber-based (NR) impact modifier for polystyrene. SNR is produced through emulsion polymerization of styrene monomer and deproteinized natural rubber (DPNR) latex. The styrene to DPNR ratio is 25:75 (wt/wt). SNR is vulcanized using sulfur vulcanization system with 1.5 phr sulfur loading for each blend. Each PS/SNR blend contains 20% rubber. Three different vulcanization techniques are proposed to produce SNR vulcanizates: mixed system (in situ mixing together with physical mixing using two roll mills), in situ vulcanization, and physical mixing using two roll mills. PS/SNR blends show the in situ vulcanization process produce SNR vulcanizate, which gives the blends with better tensile properties and impact strength compared with the mixed system and physical mixing. The morphology in PS/SNR blends of PS/R1, PS/R2 and PS/R3 have further prove that SNR has better interaction with PS matrix compared with PS/*DPNR. PS/R3, which because they have in situ vulcanization SNR vulcanizate prepared by latex-based formulation, successfully produce SNR vulcanizates that can contribute as a natural rubber-based impact modifier. [ABSTRACT FROM AUTHOR]

Thermoplastic elastomer composites of ethylene vinyl acetate (EVA)/natural rubber (NR) blends filled with palm ash were prepared by melt-mixing using a Haake Rheomix Polydrive R600/610 at 120°C with rotor speed of 50 rpm for 10 minutes. Increase in palm ash loading in composites resulted in increase the value of stabilization toque, Young's modulus and swelling resistance of the composites, but decreased the tensile strength and elongation at break. Scanning electron microscope micrographs revealed that higher filler loading resulted in agglomeration of palm ash in the composites. When smaller particle size of palm ash was used, further improvement in tensile strength, elongation at break, swelling resistance and stabilization torque value were observed. [ABSTRACT FROM AUTHOR]

At high temperatures, oxidative ageing affects only the rubber near the surface, as essentially all the oxygen is consumed by reaction with antioxidant or rubber before it can diffuse into the bulk. A resinous oxidized layer is formed and in the center of large components is essentially anaerobic. The inhomogeneous natures of ageing for a large rubber component were carried out utilizing thickness effect measurements. The effect of ageing at different distances from the surface was studied using volume swelling measurements. Based on diffusion and chemical reactions theory, an estimation of the oxidized layer formation during ageing can be calculated provided the reaction rate is constant and the diffusion coefficient for given ageing temperature is known. For this purpose, oxygen uptake measurements were carried out in pure oxygen at 100°C. [ABSTRACT FROM AUTHOR]