Preparation Of Reclaimed Natural Rubber By Low-temperature Liquid-phase Chemical Method And Investigation Of Its Desulfurization Mechanism

With the development of society,the amount of waste rubber increases year by year.However,the stable three-dimensional cross-linked structure in rubber makes it difficult to recycle these waste rubbers,which has a significant negative influence on the sustainable development of society.Moreover,waste tire rubber is an important carbon-based energy,and the recycling of carbon-based energy is an important way to achieve "carbon peaking and carbon neutrality".Therefore,it is of great significance to the rubber industry to achieve high-value reclamation of waste tires.In order to solve the environmental pollution of waste rubber and increase the reusability of rubber,in this paper,we prepare excellent and stable reclaimed rubber(powder)by a low-temperature liquid-phase chemical desulfurization method,and investigate its desulfurization mechanism.The main studies are as follows:(1)Diphenyl disulfide(DD)is selected as the desulfurizing agent and xylene is used as the solvent for the desulfurization reaction of vulcanized natural rubber,and the relationship among temperature,the concentration of the desulfurizing agent and time are explored,and the mechanism is also explored.The results indicate that the desulfurization is carried out by the sulfur-sulfur bonds exchange reaction between DD and cross-linkling bonds.The excellent performance of reclaimed rubber can be obtained by reacting at130 ℃ for 4 h.The tensile strength of composites containing 20wt%reclaimed rubber is 21.8 MPa,which is higher than that of natural rubber.(2)The desulfurization mechanism of the desulfurization reagent dithiothreitol(DTT)is investigated by simulating the desulfurization reaction of small molecules and the stress relaxation behavior of rubber,and it is determined that DTT could target to break the cross-linking bonds without destroying the main chain of rubber.In order to suppress the phenomenon of Mooney viscosity rebound of reclaimed rubber,different reclaimed rubber capping agents are selected to follow up the effect on gel crosslink density,sol content and Mooney viscosity of reclaimed rubber,and stable reclaimed rubber is obtained.Stable reclaimed rubber is obtained after investigation,with only about 4% decrease in sol content and only 9 units increase in Mooney viscosity after 15 days of storage,and with good processing properties.(3)The chemical desulfurization method of low temperature is used to regenerate the waste tire tread powder initially,and DD and DTT are used as desulfurizing agents respectively.The performance of the reclaimed rubber powder is investigated,and their mechanical properties with natural rubber are much higher than waste tire rubber powder,and the high value recovery of waste tire tread powder is realized.