| Natural rubber has its unique high elasticity and Often used in medical,automotive, scientific research and military fields.However,there are a large number of unsaturated carbon carbon double bonds in the molecular chain, which is easy to react under UV light, heat, oxygen, ozone, stress and metal ions. After aging, the use of natural rubber decreased, there are hidden dangers in the application process.In the paper,We selected six strains of natural rubber (RRIM600、PR107、Reyan879、Reyan 73397、Reyan 525、Reyan 72059 ) from Three regions(Danzhou, Qionghai, Haikou). we studied the content of metal components in the natural rubber latex and the thermal oxidative aging properties, UV aging and ozone aging properties. On this basis, we continue to explore the effects of these seven main metal components on the aging properties of NR vulcanizates.We know the relationship between the content and the content of metal components. We study in heat and oxygen aging properties, tensile strength of Danzhou Reyan 73397 samples showed a minimum rate of 17.22%, excellent heat oxygen aging properties; we study ultraviolet aging performance, tensile strength of Danzhou Reyan 525 samples showed a minimum rate of 32.72%,good UV resistance aging; aging properties of ozone in our research,changes of tensile strength of Danzhou Reyan 73397 samples showed a minimum rate of 56.78%, relatively better anti ozone aging properties.In contrast with different types, and natural rubber vulcanizates with different content of aging physical and mechanical properties, Na+, K+, Ca2+, Mg2+ of the four metal components basically does not affect the natural rubber anti-aging properties, but Cu2+, Mn2+, Fe3+heat oxygen three metal components significantly reduced natural rubber curing aging resistance, ultraviolet aging resistance, ozone resistance. The change rate of the tensile strength of natural rubber vulcanizates containing Cu ions was 68%, and the properties of vulcanizate were greatly damaged.The changes of microstructure of natural rubber containing Cu2+, Mn2+ and Fe3+ were studied in aging (thermal oxidative aging, UV aging and ozone aging).The sample after aging of molecular weight and molecular weight distribution(GPC) analysis, infrared (ATR-FTIR) analysis, DSC analysis, NMR crosslink density analysis can know the aging process of molecular weight change, group change, glass transition temperature and the changes of crosslink density change.According to GPC analysis, Cu2+, Mn2+ and Fe3+ ions accelerate the change of molecular weight in the aging process of natural rubber. By the ATR-FTIR analysis, the natural aging of rubber crosslinking and fracture in the reaction process, the peroxide groups showed the presence of oxidation reaction, methyl,lactones, acid formation indicated the presence of cleavage reactions of peroxy radicals with long chain free radicals and ether indicates crosslinking reaction.The DSC analysis showed that the glass transition temperature of the samples with Cu2+, Mn2+ and Fe3+ ions decreased with the increase of the ionic content,while the width of the glass transition zone became wider with the increase of the ion content. According to the analysis of the nuclear magnetic resonance crosslink density, Cu2+, Mn2+ and Fe3+ ions can accelerate the decrease of the crosslinking density in the aging process. Through the above analysis, we can know that the effect of Cu2+ on aging performance is more than Mn2+ and Fe3+. |
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