Study On The Aging Of Styrene Butadiene Rubber

Rubber plays an important role in polymer.SBR is a general type of synthetic rubber with the largest consumption,which has been widely applied because of its excellent performance.But during the storage and use process,environmental factors?oxygen,light and thermal?often influence SBR,which results in poor performance after aging.Therefor,the study of aging behavior and aging mechanism can lay the foundation for anti-aging.However,among all related researches so far,little work has been done in this field of micro-structure and aging mechanism analysis.And also,fewer works have analyzed the correlation between natural aging and artificial aging.In this paper,1H-NMR,FT-IR and UV-Vis were used to study the aging of two kinds of SBR?SBR-1502 and SBR-SiO₂ containing filler SiO₂?.All results were covered as follows:1.Study on UV agingAfter UV aging of SBR,it was concluded that,the ability of resistance to UV of SBR was very poor.And the ability of resistance to UV of SBR was significantly improved by SiO₂.The functional groups of SBR showed the following order of UV aging reaction activity:a-H>1,2-polymerized double bond>1,4-polymerized double bond>benzene ring.During UV aging,the mechanism showed that a-H of double bond was oxidized to peroxide alcohol,then to aldehyde,with the generation of small molecules by degradation.And ultimately the large ?-conjugated structure was formed.2.Study on thermal oxidative agingAfter thermal oxidative aging of SBR under the temperature of 120?,140?and 160?,the results showed that,the ability of resistance to thermal oxidative of SBR was good.The molecular structure of SBR showed no obvious change under 120?.The molecular structure of SBR under 140? changed more slowly than under 160?.So the temperature rising could speed up the process of thermal oxidative aging.And SiO₂ didn't work for improving the ability of resistance to thermal oxidative aging.The functional groups of SBR showed the following order of thermal oxidative aging reaction activity:?-H>1,2-polymerized double bond>1,4-polymerized double bond>benzene ring.During thermal oxidative aging,the mechanism showed that a-H of double bond was oxidized to peroxide alcohol,then to ketone.3.Study on chemical media agingAfter chemical media aging of SBR under the solution of 5%H₂O₂,5%KMnO₄,5%HC1,5%NaOH and 5%NaCl,the results showed that,the ability of resistance to H₂O₂ of SBR was general while the ability of resistance to KMnO₄ of SBR was poor.And SiO₂ worked for improving the ability of resistance to H₂O₂ and KMn04.The ability of resistance to HCl of SBR was not bad and the ability of resistance to NaOH of SBR was good.And SiO₂ didn't work for improving the ability of resistance to HCl.The ability of resistance to NaCl of SBR was excellent.The functional groups of SBR showed the following order during H₂O₂,KMnO₄ and HCl reaction activity:a-H>1,2-polymerized double bond>1,4-polymerized double bond>benzene ring.During H₂O₂ and KMnO₄ aging,the mechanism showed that a-H of double bond was oxidized to peroxide alcohol,then to aldehyde,with the generation of small molecules by degradation.During HCl aging,the mechanism showed the addition reaction.4.Study on natural agingAfter natural aging of SBR in Xiamen for one year,the results showed that,during natural aging,UV made a bigger difference firstly.And thermal oxidative made a bigger difference secondly.And Si02 could protect SBR against UV from sunlight.The functional groups of SBR showed the following order during natural aging reaction activity:a-H>benzene ring>1,2-polymerized double bond>1,4-polymerized double bond.During natural aging,the mechanism showed that firstly a-H of double bond was oxidized to peroxide alcohol,then to aldehyde with the generation of small molecules by degradation,and then to carboxylic acid,with large?-conjugated structure formed,and secondly peroxide alcohol was oxidized to ketone.And the curves of UV aging,140? and 160? thermal oxidative aging,and natural aging were built.The correlation between artificial aging and natural aging were built innovatively.It was found that the effect of 7 days of 140? thermal oxidative aging equaled to the effect of 4 months of natural aging.And the effect of 6 days of UV aging equaled to the effect of 12 months of natural aging,which provides some academic bases and references for the aging study and service life prediction of SBR.