Structure And Properties Of XNBR/EVM Rubber Blended Vulcanizates

Carboxylated nitrile butadiene rubber(XNBR)has good tensile strength,tear strength,hardness,abrasion resistance,adhesion,oil resistance and ozone aging resistance.As a polar rubber,ethylene vinyl acetate rubber(EVM)has excellent heat,ozone,oil and weathering resistance due to the presence of polar side groups and saturated main chains.The combination of good oil and temperature resistance of EVM-GMA and excellent performance of XNBR is an important guideline for the development of new and used materials.Based on the above reasons,this project will systematically investigate the structure and properties of the copolymer by combining XNBR and EVM-GMA,which is divided into the following aspects.Firstly,the effects of different vulcanization systems on the properties of carboxylated nitrile butadiene rubber(XNBR)were studied,and the processing properties of the blends,the mechanical properties of the vulcanized rubber and the heat and oxygen aging properties were tested and analyzed.The experimental results showed that the peroxide vulcanization system and the effective sulfur vulcanization system could significantly shorten the process positive vulcanization time(t₉₀)of the blends and improve the vulcanization efficiency,and the XNBR vulcanized rubber made by the common sulfur vulcanization system had better mechanical properties,and the XNBR vulcanized rubber made by the peroxide vulcanization system and the metal oxide vulcanization system had better resistance to compression change,and when DCP was used as vulcanizing agent,the When DCP was used as vulcanizing agent,the compression resistance of vulcanized rubber increased with the increase of DCP dosage and stabilized when the dosage of DCP was 3phr,and when Zn O was used as vulcanizing agent,the compression resistance of vulcanized rubber increased with the increase of Zn O dosage;the XNBR vulcanized rubber with effective sulfur vulcanization system had the best heat and oxygen aging resistance.The EVM-GMA/XNBR vulcanizates were prepared by using carbon black and silica as reinforcing fillers,and the processing properties,mechanical properties and microscopic morphology of the vulcanizates were tested and characterized.The experimental results showed that the addition of filler could shorten the t₉₀,and at the same time,the mechanical properties and wear resistance of the vulcanizates were improved.Compared with silica,when carbon black was used as reinforcing filler for EVM-GMA/XNBR,the scorch time(t₁₀)of the blended rubber was not changed much and t₉₀ was shortened,which improved the vulcanization efficiency while ensuring better processing safety;the tensile strength of the blended rubber was higher and the wear resistance was better,and it also had better resistance to compression changes.The best overall performance of EVM-GMA/XNBR was achieved when 40phr carbon black was used as reinforcing filler.The effects of the ratio of EVM-GMA and XNBR on the processing and mechanical properties of EVM-GMA/XNBR adhesives were investigated.The experimental results showed that at 170?,the epoxy group in EVM-GMA opened the ring and reacted with the carboxyl group in XNBR to produce cross-linked bonds,and the EVM-GMA/XNBR compound containing only EVM-GMA/XNBR cross-linked network only swelled but not dissolved in tetrahydrofuran;with the addition of EVM-GMA,the t₉₀ extended and the vulcanization rate became slower.With the increase of EVM-GMA,the strength and abrasion resistance of the vulcanized rubber itself decreased slightly.At the ratio of EVM-GMA/XNBR of 90/10,the best compressive permanent deformation resistance of the vulcanized rubber was achieved.Compared with XNBR vulcanized rubber without EVM-GMA,the aging resistance of the vulcanized rubber can be improved by adding appropriate amount of EVM-GMA,and the tensile strength retention rate can be more than 60%when the amount of EVM-GMA is more than 20phr.