The Effect Of Multi-Network On NR Vulcanizates Machenical Properties, Structure And Appearance Change During Fatigue

By tensile and tearing testing, rubber process analysis machine(RPA), hot aging testing, Akron abrasion and dynamic fatigue testing, it studied the effect of muti-network(CB-CB network, CB-polymer network and curing network) on tensile properties, tearing properties, abrasion properties, compression heat build-up properties, dynamic machenical and dynamic fatigue properties of NR compounds and vulcanizates;it also studied the micro structure and appearance change of NR vulcanizates with different CB and sulfur content during the fatigue process by FTIR-ATR and SEM testing.CB-CB and CB-polymer network in NR compounds and vulcanizates inceased as the growth of CB content; CB-CB and CB-polymer network in vulcanizates were higher than in NR compounds, curing network decreased a little as the increase of CB content.As sulfur content increased, CB-CB and CB -polymer network did not change much in NR compounds but had little increase in NR vulcanizates; at the same time, the curing network increased as sulfur content went up.As CB content increased, loss factor(loss modulus)~strain dependence of NR compounds and vulcanizates, tensile stress at 300% elongation, hardness, compression heat and permanent deformation increased, the tensile strength, tear strength, Akron abrasion and fatigue properties had highest value, also the hot aging rate of vulcanizates decreased as CB content went up; as sulfur content went up, loss factor(loss modulus)~strain dependence of NR compounds and vulcanizates decreased, 300% stress , hardness, hot aging rate, Akron abrasion and fatigue properties increased, but compression heat and permanent deformation had a decrease, the tensile strength and tear strength of NR vulcanizates had an increase as sulfur content raised. With dynamic fatigue process going on:For low CB filled NR vulcanizates, curing single bond and double bonds decreased, double bonds content in cis 1,4-IR structure did not change much, also C=O content increased a lot in later stage of fatigue process; for high CB filled NR vulcanizates, curing single bond and double bonds content in cis 1,4-IR structure increased, C=O content did not change much; for low sulfur content vulcanizates, curing single bond had highest value, double bonds content in cis 1,4-IR structure, sulfur single bond and double bonds have an decreased, conjugate diolefin, triolefin content and C=O content increased,but end-olefin group content did not change much; for high sulfur content vulcanizates, sulfur single bond and double bonds decreased, conjugate diolefin, triolefin content and C=O content had highest value.