不同促进剂对NR平衡硫化体系的影响

EFFECT OF DIFFERENT KINDS OF ACCELERATORS ON THE EQUILIBRIUM CURE SYSTEM OF NR

研究了促进剂的种类，促进剂并用及硫化温度等条件对平衡硫化体系（ＥＣ）硫化天然橡胶（ＮＲ）的影响。结果表明，噻唑类促进剂具有较低的硫化返原率，尤其是促进剂ＤＭ，在１３０～１７０℃的硫化温度范围内，硫化２小时的硫化返原率均为０；当促进剂ＮＯＢＳ或ＣＺ与ＤＭ并用时，可缩短正硫化时间；当ＤＭ摩尔分数分别为４０％和５０％左右时，不仅使硫化２小时的硫化返原率为０，而且可使３００％定伸应力保持恒定；以ＮＯＢＳ或ＣＺ为主促进剂时，正硫化时具有较高的拉伸强度和撕裂强度，但硫化２小时时的降低幅度比ＤＭ大。

Effects of different kinds of accelerators,blending ratio and cure temperature on natural rubber(NR)cured with equilibrium cure system(EC)were studied.It can be concluded that thiazole type accelerators had lower reversion than sulfenamide type ones,especially 2,2 dibenzothiazyl disulfide(DM)had a zero reversion within two hours cure period during 130-170℃ cure temperature.When blending N-oxydiethylene-2-benzothiazyl sulfenamide(NOBS)or N-cyclohexyl-2-benzothiazyl sulfenamide(CZ)with DM,optimum cure time was shortened and delayed action reduced. When mole ratio of DM in NOBS was 40% and in CZ 50% respectively, the vulcanizate had not only a zero 2 hours curing reversion but also maintained a constant 300% modulus;A high tensile strength and tear strength of vulcanizate of optimum cure was obtained when NOBS or CZ was used as a main accelerator.The tensile strength and tear strength at 2 hours cure time of vulcanizate decreased less when DM was used as a main accelerator than when sulfenamide was used as a main accelerator.