Improvement Of Adhesion And Fast Vulcanization Of EPDM

EPDM is widely used in the fields such as conveyor belts,automotive sealing strips for its excellent heat resistance and aging resistance.Its special molecular structure leads to weak chemical reactivity and low surface energy of the rubber,which results poor adhesion.As the same time,the higher saturation of EPDM results in the slow curing rate.How to solve the problem of slow curing speed and poor adhesion performance of EPDM has become the focus of attention.In this paper,different grades of EPDM are selected as the research objects,and the effect of microstructure on its properties are compared.The results showed that the adhesion property of compounds decreased and mechanical strength of vulcanizates increased with the increase of ethylene content.The change of ethylene content showed no obvious effect on the curing characteristics.The adhesion strength of compounds became larger,curing time was shortened and the mechanical properties of vulcanizate were improved with the increase of ENB content.K6950 showed a faster curing speed,better adhesion strength and comprehensive performance.The effects of sulfur and TPZ content on adhesion,vulcanization and mechanical properties of EPDM were investigated.The results showed that the adhesion properties of compound showed no change and the adhesion strength of vulcanizate gradually increased with the increase of sulfur and TPZ content.The crosslink density and mechanical strength of the vulcanizaties gradually increased with the increase of sulfur content.The activation energy of the vulcanization reaction decreased gradually through the simulation calculation of vulcanization kinetics.The curing speed became faster,the tensile strength and modulus of the vulcanizate were gradually increased with the increase of sulfur content.The effects of petroleum resin(C5),p-octyl phenolic resin(SL-1801),p-tert-butyl phenolic resin(SL-T421)and coumarone resin on EPDM properties were studied.Theresults showed that the adhesion strength of compounds were improved by incorporating four kinds of resin.The addition of resin into EPDM reduced the curing speed of compound,decreased the modulus of the vulcanizates,while increased the elongation at break.SEM image showed that the compatibility of tackifying resin with the rubber influence the adhesion strength;the improvement of the compatibility was beneficial to adhesion properties.The effects of modified silica with different modifiers on properties of EPDM were investigated.The results showed that the adhesion properties of compound have been improved by adding modified silica,and modified silica with KH550 showed better effect.The curing time was prolonged and elongation at break of vulcanizates were lowered with the increase of silica and modified silica content.After further study on the effect of different content of KH550 on the performance of EPDM,the results showed that the best value of adhesion strength of the compound and vulcanizate was reached with the increase of KH550 content.The curing time of compound was shoretened,the hardness and tear strength of the vulcanizate increased,the elongation at break decreased with the addition of KH550.The strength of compound was changed through the combination of N330 and N550,and the relationship between the strength of compound and adhesion properties was studied.The adhesion strength increased gradually with the increase of N330 content,therefore the adhesion properties could be improved by increasing the strength of compound.The scorch time and curing time of compound showed no variation,the tensile strength of the vulcanizates were improved with the increase of N330 content.The effect of different environmental factors and storage time on the adhesion performance of compounds were compared.The results showed that the adhesion strength decreased fastest and decreases by 3.26% when the compound was storaged for 5-7 days.The adhesion strength increased by 21.4% when the ambient temperature increased from35? to 45?.The adhesion strength decreased by 11.7% when the relative humidity increased from 75% to 85%.