Preparation and characterization of High-Performance Carboxylated-NR/NBR reinforced with silanized Silica-Carbon black: A potential material for automobile tire tread design

Carboxylated natural rubber-(XNR)/acrylonitrile butadiene rubber (XNBR) reinforced Carbon black (CB)-Silanized Silica (SS) compositions were prepared and cured with sulfur(S) and peroxide (DCP) at 160 °C separately. The cure, chemical and mechanical properties etc. were systematically studied. A low content of XNBR in the blend (BL) resulted in better physico-mechanical properties. The best composition KC3 (30 phr XNBR and 70 phr XNR-Sulfur cured) recorded a bound rubber content, BR (%) of 37.5% with lower t₉₀(high cure rate) compared to KC6(50phr XNBR and 50phr XNR-DCP cured), which recorded BR (%) ~ 17.5%. Interestingly, KC6 recorded the highest crosslinking density (N), torques (M_H and ∆M) and hardness. For instance, KC6 recorded over 109, 98, 230, 35 and 1151% increments in M_H, ∆M, modulus at 300% (M300), hardness (Shore A) and N respectively compared to KC3. However, KC3 exhibited 28, 68, 240%, and 1,399,900% increments in wear resistance, stress, strain (%) and fatigue respectively, as compared to KC6. While the improvement in KC3 was due to the presence of stronger network structures like —BL—S_x—BL—CB—S—SS—BL in addition to interactions like hydrogen (—C ≡ N----H—O) and polar (^ẟ+C ≡ N----O^ẟ+—H)), that of KC6 was mainly linked to weak and physical networks.