Study On Co-Vulcanization Systems Of CR/CM Rubber

Most of the cover rubber of flame retardant conveyor belt is composed of CR, reducing the use amount of CR instead of CM can not only weaken the adhesiveness obviously between the processing equipment and CR, but have no effect on the flame retardant property and reduce the cost of production as a whole. However, because of significant differences between CR and CM in unsaturation and unique allyl chloride structure of CR rubber, the differences of curing system between the two is obvious, and blend has serious problem of vulcanization mismatching, which causes poor mechanical properties of vulcanizates and limits the application of CRCM blends.(1)The comprehensive cross contrast experiments on ZnO/MgO of CR and NA-22/S^ DCP/TA1C、PT75/903、FSH、TCHC of CM were done, and the two rubber vulcanizing properties cured by the common curing agent of both rubber respectively was explored. And we focus on the ZnO/MgO/DCP/TAIC curing system to optimize formula, to explore curing rules of the two-phase. Results show that CR can be vulcanized by the main curing system of CM, and compared with ZnO/MgO, curing rate becomes faster, the scorch time shorter, and physical performance lower. ZnO/MgO,the curing system of CR, is not on the activity of CM in rubber vulcanization. Blend processing mobility is better than CM, viscosity and mechanical properties were between the pure CR and CM. The tensile strength reached 19.9MPa,with the best comprehensive properties of blends,the ratio of ZnO/NA-22/DCP/TAIC being 4.25/0.5/0.8/1.3.(2)CM was pre-vulcanized in different degree to explore the influence of co-curing performance the pre-vulcanization process temperature on CM and CR blend. For different CR/CM ratio, we carried out a series of performance research based on proper pre-vulcanization process. Results show the longest scorch time, the shortest curing time, tensile strength reaching to 14.9MPa,2.1 MPa higher than the blank control group when pre-curing temperature was 110 ℃-120 ℃. Pre-vulcanization process can significantly improve co-curing of CR/CM blend based on these results. And For CR/CM blend, the tensile strength of blend of ratio of 70/30 reached the maximum value of 15.7MPa as the crosslink density of rubber gradually decreased with the increase of CM content.(3)By graft modification method for CM rubber functionalized modification, emphatically explores the vulcanization activity of modified CM rubber and co-curing performance with CR Rubber. Results indicated that there is a small amount of acid anhydride groups grafted onto the CM backbone characterized by infrared spectroscopy; the vulcanization rate of modified CM rubber was accelerated markedly, and the mechanical performance was improved significantly, in which the modified CM tensile strength cured by DCP/TAIC and TCHC were increased to 17.0 MPa and 25.5MPa, higher than the tensile stress of 8.3 MPa and 16.5MPa of CM; and ZnO produced certain sulfofication on the modified CM rubber; The tensile strength was increased by 7.5MPa, tensile stress by 11.51 MPa; modified CM/CR curex by ZnO, whose curing rate and mechanical properties are obviously improved and the tensile strength and elongation at break were increased by 3.3MPa and 22%, respectively, has a total better co-curing performance.