Abstract
Polymer blends are prepared by melt mixing, solution or latex blending. Thermoplastic vulcanizates (TPVs) are generally produced by melt mixing. TPVs can be co-injected or co-extruded to produce complex articles built from very soft/hard components. Dynamic vulcanization would give rise to a uniform and fine distribution of rubber and thermoplastic phases. The aim of this study was to identify a suitable dynamic vulcanization system to produce natural rubber (NR)/low-density polyethylene (LDPE) blends with improved chemical, ageing and morphological properties. Three 50:50 NR/LDPE blends were prepared by varying the vulcanizing agent as sulphur, dicumyl peroxide (DCP) and 50:50 sulphur: DCP. A control was prepared without any vulcanizing agent. All these blends were prepared by melt mixing. The blends were characterized using FTIR spectroscopy and SEM analysis of tensile fracture surfaces. Water absorption, swelling and ageing behaviour of the blends were investigated. Water absorption percentage of blends prepared with DCP and the mixed curing system was zero. Analysis of gel content indicated a higher crosslink density for the blend prepared with the mixed curing system compared to the other blends. Also, the former blend showed the highest retention of strength properties and elongation at break compared to the other two blends prepared with vulcanizing agents. SEM analysis showed a fine and smooth textured morphology for this blend. Results in overall indicated that the 50:50 NR/LDPE blend prepared with the mixed curing system would be suitable to manufacture heat and solvent resistant products.
Highlights
Polymer blends may be categorized in general into two broad classes: immiscible and miscible blends
In regard to the curing behaviour, the results show that the mixed curing system leads to compounds with low scorch safety and low cure rate when compared to the usual sulphur/accelerator system
According to the above figure, blends prepared with peroxide and the mixed curing system have good solvent resistance compared to the blend prepared with sulphur and the Control
Summary
Polymer blends may be categorized in general into two broad classes: immiscible and miscible blends. He used a variety of mixed peroxide-sulphur curing systems and tested to study the mechanical properties of the vulcanizates.
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