Surface modification of perlite by using silane for the enhancement of heat aging resistance of natural rubber vulcanisates

วารสารวิชาการและวิจัย มทร.พระนคร, 13(2) : 128-141The enhancement of mechanical properties of natural rubber vulcanisates was expected by surface modification of perlite particles. Thus, the objective of the present study was to investigate the cure properties and the heat aging resistance properties in terms of stress at 100% elongation, tensile strength, and percentage elongation at break after surface modification. Furthermore, the rebound resilience and abrasion resistance of perlite treated with silane filled in NR vulcanisates were investigated. In a comparison, the properties of clay-filled NR vulcanisates were determined. The results reveal that surface modification by using silane caused a reduction of scorch time and cure time but an increase in torque difference and swelling resistance. Also, surface modification gives better perlite-NR interactions before and after aging. The better heat resistance properties of perlite-filled NR vulcanisates than those of clay-filled vulcanisates is detected from relative property data. Nevertheless, a lower percentage of rebound resilience and abrasion resistance of perlite-filled vulcanisates before and after surface modification than those of clay-filled vulcanisates are observed. This is owing to the large particle size, low specific surface area, poor dispersion, and agglomeration of perlite in NR vulcanisates.Rajamangala University of Technology Phra Nakho

Thermal and rheological behavior of reactive blends from metallocene olefin elastomers and polypropylene

Reactive blends of metallocene polyolefin elastomers (POE)/polypropylene (PP) with 60/40 composition were prepared with an organic peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, and a bis-azide derivative, diphenyloxid-4,4'-bis(sulfonylazide) (BSA). Ethylene-1-butene (EB) and ethylene-1-octene (EO) copolymers and elastomeric polypropylene (ePP) were used as the elastomeric phase. The effect of elastomeric phase on the thermal, rheological, morphological and mechanical properties of the thermoplastic vulcanizates (TPVs) or dynamic vulcanizates were studied. All TPVs depicted pseudoplastic behavior and blends cured with azide curative showed higher viscosities. The TPVs showed both dispersed and continuous phase morphology that depends on the elastomeric phase type revealing a limited degree of compatibility between PP and the elastomers EO or EB. On the other hand, the TPV PP/ePP showed a uniform morphology suggesting an improved compatibility. Substantial changes observed in physical properties were explained on the basis of blends' morphology and dynamic vulcanization. The results confirm that the mechanical properties are more influenced by the elastomeric phase than by the curative agent. This study revealed a broad new range of opportunities for POE-based TPVs