Preparation Of Multifunctional Additives Thiadiazole Containing Selenium And Its Effect On Crosslinking Network Structure Of Styrene Butadiene Rubber

Vulcanization accelerators can effectively improve the vulcanization properties of rubber and enhance the physical and mechanical properties of rubber,which are an important boost for the vigorous development of the rubber industry.Commonly used medium-speed accelerators M and DM also have problems such as slow vulcanization speed,poor physical and mechanical properties,and easy carcinogenesis;thiadiazole derivatives green additives are not carcinogenic,but their vulcanization properties and physical and mechanical properties are still poor,which limit their scope of application.We found that the comprehensive performance of the accelerator was greatly improved after introducing molecular selenium.Based on this,this thesis introduced molecular selenium into thiadiazole derivatives,synthesized two highly effective multifunctional rubber additives.studied their effects on vulcanization acceleration and physical and mechanical properties of styrene butadiene rubber(SBR),and discussed their mechanism of action in styrene-butadiene rubber and its influence on the cross-linking network structure of rubber.The main contents are as follows:(1)In this thesis,two rubber accelerators were synthesized: selenium-containing dimercaptothiadiazole(SeDMTD)and selenium-containing 2-amino-5-mercaptothiadiazole(SeAMTD),and their chemical structure and physical properties were characterized by infrared,XPS,elemental analysis,etc.(2)The vulcanization performance and vulcanization kinetic parameters of the accelerator SeDMTD in pure SBR were explored and compared with the accelerators M,DM,TMTD and ZDC.The results show that the vulcanization speed of SeDMTD is faster than M and DM,and slower than TMTD and ZDC;the activation energy parameter of SeDMTD is less than M and DM,and greater than TMTD and ZDC.In addition,the physical and mechanical properties of the accelerator SeDMTD system in SBR/N550 were explored.Compared with the M,DM and ZDC systems,the vulcanization efficiency,crosslinking density and strain performance of the accelerator SeDMTD system were improved,but slightly lower than TMTD;Compared with M,DM,TMTD and ZDC,the tensile properties of the accelerator SeDMTD system are improved by 34%,36%,33% and 32% respectively;the heat-resistant oxygen aging performance is better than that of TMTD and ZDC.(3)In view of the requirement of sufficient scorch period for rubber in actual production,this thesis synthesized a selenium-containing accelerator with side group with amino group to improve the scorch time of the vulcanization system.Studies have shown that the scorch time of the newly synthesized accelerator SeAMTD in pure SBR and SBR/N550 composites was increased by 26.4% and 85.1%,respectively,compared with the accelerator SeDMTD,which improved the safe processing time of the SeAMTD system.In addition,the effect of the accelerator SeAMTD on the vulcanization and mechanical properties of pure SBR and SBR/N550 was roughly the same as that of SeDMTD,which further expanded the application range of the new accelerator.(4)The mechanism of the accelerator SeDMTD and the accelerator SeAMTD in rubber was roughly similar to the effect on the rubber cross-linking network.In the vulcanization process,sulfur-free and zinc-free vulcanization could be achieved.They separated out molecular selenium during the vulcanization process to directly participate in the cross-linking of the rubber molecular chain,which improved the cross-linked network structure and enhances the overall performance of the rubber.