Study Of The Hot-air And Ozone Aging Process Of SIBR

The effects of hot-air and ozone aging on SIBR, as well as the function ofantioxidant during the whole process of aging were investigated with Fouriertransform infrared spectroscopy/attenuated total reflection (FTIR-ATR), thermalanalysis (DSC and TGA) and mechanical analysis. IR and SSBR played as acomparison because of the similar structure from beginning to ending.The results of hot-air aging show that carbonyl groups produce in all threevulcanizates in the aging process, SIBR and SSBR have a tendency of s-shapedincrease while IR had a linear increase. SIBR has plenty of3,4-structure of isoprene inSIBR, which generates a larger amount of conjugated carbonyl groups at highertemperature of140oC. Oxidation exothermic peak of SIBR gum is more closed toSSBR and dynamic parameters of gum as well as unfilled SIBR vulcanizate are in themiddle of SSBR and IR. Compared with IR, SIBR has a better resistance of aging atdifferent aging temperature and a higher aging coefficient. This could account for itsgood thermal resistance.Besides, ozone aging was studied with SIBR, including changes of molecularstructure after aging, changes of ozone crack and mechanical properties before andafter ozone aging. The results show that changes of double bond structure of SIBR aresimilar to SSBR—they all exhibited a tendency of flat increase in the latter part ofaging. Considering the changes of carbonyl group during the aging process, IR has aworst resistance to ozone. Absorption peak intensity of carbon-oxygen group in ozonecrack of vulcanizates are relatively high and SIBR highest. Changes of ozone crackmorphology and initial crack time of SIBR are in the middle of SSBR and IR.However, SIBR has a good resistance to ozone crack due to its slow crack growth.Meanwhile, mechanical properties of SIBR are relatively high after ozone aging. Fromthe above can prove that SIBR has a better resistance to ozone. At last, the study focused on the influence of antioxidant on the aging process ofSIBR, including the effect of antioxidant on molecular structure and mechanicalproperties and the consumption of antioxidants during the aging process. The resultsshow that absorption peak of carbonyl group of SIBR, SSBR and IR is not obviousduring the aging process. The effect of antioxidants of RD is better than4020onthermal aging process. Antioxidant D37has a better effect to double bond in isoprenethan that in butadiene and its anti-aging function to SIBR is in the following of SSBR.Antioxidants D37could not only prevent emerging of crack but also lower the crackgrowth of unfilled vulcanizates and the initial crack time of SIBR is between SSBRand IR. The crack of SIBR is deeper and longer than that of SSBR and IR, but thenumber of cracks has a tendency to decrease when carbon black added to the matrix.However, mechanical properties of SIBR with antioxidant D37has adramatic dropafter ozone aging.