防护体系对NBR/EVM硫化胶交联密度及耐老化性能的影响

Effect of Protection System on the Crosslinking Density and Aging Resistant Properies of NBR/EVM Blends

在过氧化物硫化剂DCP（过氧化二异丙苯）作用下，研究了防老剂MB（二硫醇基苯井咪唑）用量、防老剂MB／RD（2,2，4-三甲基-1．2-二氢化喹啉靛合体）并用比对NBR／EVM并用胶硫化特性、两相交联密度、力学性能及热空气老化性能的影响。结果表明，随着防老剂MB用量的增大，NBR／EVM硫化胶的交联密度微增，热空气老化后其交联密度增大，并认为是由NBR相交联密度增大连成的。在防老剂MB用量为0．6～1．8份对，交联密度变化率最小。硫化胶的硬度和200％定神应力均逐渐增大，在防老剂MB用量为1．2份时，其耐热空气老化性能最佳。随着防老剂MB／RD并用体系中RD所占比例的增大，NBR／EVM并用胶的交联密度逐渐减小，操作安全性逐渐变好，硫化速率逐渐减小。在防老剂MB／RD并用比为1．6／0．4和1．2／0．8时，老化前后交联密度、邵尔A硬度和拉伸强度变化最小，其耐热空气老化性能最佳。防老剂MB和防老剂RD并用时具有协同效应，防护效果好。在防老剂MB／RD并用比为1．2／0．8时、随着热空气老化时间的延长，NBR／EVM硫化胶的交联密度逐渐增大，100％定伸应力、200％定伸应力和300％定伸应力逐渐增大。

With the existence of DCP（Dicumyl Peroxid）,the effects of Antioxidant MB dosage and Antioxidant MB/RD blending ratios on the vulcanization properties,two-phase crosslinking density,physical-mechanical properties and hot air aging properties of Acrylonitrile Butadiene Rubber（NBR）/Ethylene-Vinyl Acetate Rubber（EVM）blends were investigated.The results showed that,with the Antioxidant MB dosage increasing,the crosslinking density of NBR/EVM vulcanizates increased slightly, crosslinking density of vulcanizates increased after hot air aging, which were caused by the increasing of crosslinking density of NBR phase. The change rate of the crosslinking density was minimum when the MB dosage was 0.6-1.8 phr. The hardness and modulus at 200% increased slightly,the hot air aging properties was optimum when the MB dosage was 1.2 phr. With the proportion of RD increasing in the MB/RD system,the crosslinking density of NBR/EVM blend decreased,operational safety got better, curing rate decreased gradually. The crosslinking density, hardness,tensile strength alter aging was minimum and the heat aging resistance was the best when the ratio of MB/RD was 1.6/0.4 and 1.2/0.8. MB and RD had synergistic effect. When the ratio of MB/RD was 1.2/0.8 in NBR/EVM vulcanizates,with the extension of hot air aging time,the crosslinking density, modulus at 100% ,modulus at 200% and modulus at 300% increased gradually.