INFLUENCE OF CARBONIZED DIKA (Irvialgia Gabonensis) NUTSHELL POWDER ON THE VULCANIZATE PROPERTIES OF NATURAL RUBBER/ACRYLONITRILE-BUTADIENE RUBBER BLEND

Vulcanizate properties of rubber blends prepared from natural rubber (SAR) and acrylonitrilebutadiene rubber (NBR), in the presence of carbonized Dika nutshell powder (C-DNS) and carbon black (CB) as fillers were studied. Blend compositions of SAR/NBR : 0/100, 25/75, 50/50, 75/25, and 100/0 wt.%, respectively were reinforced with varying filler ratios of CB/C-DNS : 50/0, 40/10, 30/20, 20/30, 10/40, and 0/50 phr. The influence of C-DNS content and blend ratio on vulcanizate properties, such as stress - extension ratio behavior, tensile strength, elongation at break and crosslinking density were investigated. Carbonization of Dika nutshell powder significantly improved the tensile properties of blend samples. Elongation at break showed a decreasing trend with decreasing C-DNS content. However, a higher elongation at break was shown by SAR and SAR ? rich blends mainly because SAR matrix has greater chain mobility than NBR matrix due to the lower Tg of SAR (-720 c) compared to that of NBR (-400 c). An increasing trend in crosslinking density was observed for SAR and SAR ? rich blends.This is attributed to the greater chain regularity of SAR over NBR which improves on reinforcement. Marked improvement in all properties tested was obtained at 10 phr C-DNS content. This reveals that at low level of 10 phr, C-DNS proves a potential substitute filler for CB in the rubber industry, especially in the production of low-cost/high volume rubber products where strength is not critical.