The Effect Of Curing Systems On EPDM Crosslink Network And Dynamic Mechanical Properties

Firstly, we researched the curing characteristics, cross-linked differences innetwork structure, dynamic mechanical properties and physical and mechanicalproperties of mixed EPDM component of different accelerator and sulfur ratio toexplore the most reasonable promotion agents and sulfur ratio. Results showed that thescorch time and cure time both reduced, the processing safety reduced, but the curingefficiency increased during the effective sulfur content increased. Scorch timedecreased gradually with increasing of accelerantor, but there was no significantdifferences between the degree of vulcanization at the same effective sulfur content.With the A/S ratio increased, the equilibrium swelling results showed that crosslinkingdensity increased, but when A/S was5, we continued to increase the sulfur, thecrosslinking density still decreased. The tensile strength, elongation at break, modulusat100%, tear strength properties was optimized when the content of effective sulfurincreased. The strain sweep of vulcanized rubber, the more monosulfide bond anddisulfide bond content, the more significantly of storage modulus G ’ decreased, themore dependent of loss factor tan with strain.Secondly, we studied the effect of bis (1-(tert-butylperoxy)-1-methylethyl)-benzene (BIPB) and assistant agent triallyl isocyanurate(TAIC) on EPDM rubbercuring characteristics, crosslink density and mechanical properties. The results showedthat increased the both amount, the curing time decreased, promoted the vulcanizate ofEPDM, the torque difference increased. The equilibrium swelling test confirmed thisresult. But when the content of peroxide was high enough, the assistant agent contentshouldn’t be too high, because mechanical properties tests showed a decline.Finally, through the theoretical calculation, we got the relationship of total crosslink density with the content of peroxide. We got the same crosslink density, getthe peroxide content different; and NAkt drawing a comparison, The result showedthat the crosslinking efficiency did not significantly increase (increased slope of about1%) when the content of assistant agent increased. that to increase the content ofcross-linking agent TAIC, peroxide crosslinking efficiency coefficient of BIPB did notsignificantly increase (increased slope of about5%). Then in plot for (NAkt β+Ce-c),the slope of the line fitted to0.33, by inference, assistant agent TAIC in rubbervulcanization process can be vulcanized Keltan4450, and the reaction efficiency isabout33%. The assistant agent could react highly in peroxide free radical conditions,could form the C-C crosslinks with rubber, and inhibition of the macromolecular chainscission and disproportionation termination and other side-effects that was notconducive to the crosslinking. The theoretical calculation formula of the samecrosslink density test, the results showed that the maximum torque per a set offormulas MH, the scorch time TS2, curing time tc90and the constant of reaction rateCR values were similar, the equilibrium swelling test showed that crosslinking densitydecreased but was very small.