| Eucommia ulmoides gum(EUG)is a very precious natural rubber resource in China.It has the characteristics of low heat generation,low rolling resistance,acid and alkali resistance and good insulation.Compared with plastics,it has lower melting point and crystallization ability,which makes eucommia ulmoides gum and natural rubber blend processing has obvious advantages.the research on EUG/NR blends mainly focused on processability,fatigue,crystallization behavior and so on.However,there is a more serious problem in both of them,that is,their molecular main chain contains a large number of unsaturated double bonds,which makes them susceptible to oxidation reaction during use,and has poor heat resistance and oxidative aging resistance.Therefore,it is particularly important to study the thermo-oxidative aging properties and protection of EUG/NR blends.In this paper,the thermo-oxidative aging properties and protection of EUG/NR blends were studied from vulcanization system,the blending ratio of EUG/NR and the protection system.The effects of different vulcanization systems on the thermo-oxidative aging properties of EUG/NR blends were studied.The experiments were carried out by the vulcanization characteristics,mechanical properties,mechanical properties retention after aging,crosslink density,DSC,TG,and the properties before and after aging of the gelled oxygen were analyzed.The results showed that the rubber used in the SEV1 vulcanization system has relatively high mechanical properties,good heat-resistant oxygen aging performance and good thermal stability.In the research,it was found that the main EUG phase reacted firstly in the aging process.The effects of different EUG/NR blending ratios on the thermo-oxidative aging properties of blends were studied.The experiments were carried out by mechanical properties,crosslink density,infrared analysis,TG and other methods to analyze the performance of different EUG fractions before and after aging.The results showed that the tensile strength and elongation at break gradually decrease with the gradual increase of the EUG fraction before the aging,and the 100% modulus and hardness gradually increase.In the early stage of aging,the crosslinking effect of compound rubber was dominant,,and the gum was used to produce some hydroxyl or carboxyl groups in the molecule during the aging process or to form compounds containing these groups.It can also be seen from TG that the molecular chain and the crosslinked network did not show significant damage during the initial stage of aging.The effect of the protective system on the thermo-oxidative aging properties of EUG /NR blends was studied.The experiment evaluates the protective effect of the antioxidant agent inthe aging process by vulcanization characteristics,mechanical properties,crosslink density,retention of mechanical properties after aging,and DSC.The research results showed that the addition of antioxidant can help the vulcanization of the rubber together,and can improve the mechanical properties of the rubber.It can be seen that the antioxidant 4010 NA has the best protection effect and good thermal stability when the rubber was subjected to thermal oxygen aging.It was found that the antioxidant 4010 NA was mainly delayed and further crosslinked by the crosslinked network of the EUG phase in the blends. |
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