Preparation Of Chitosan-based Macromolecular Rubber Additives And Their Application In Styrene-butadiene Rubber

At present,most of the commonly used rubber additives are small molecular compounds,which have many disadvantages,such as easy migration,volatility,and poor extraction resistance.During the process and usage of rubber products,physical loss of rubber additives are easily occurred,resulting in not only impairing comprehensive performances of rubber products,but also causing environmental pollution.Therefore,how to effectively reduce the mobility of rubber additives and improve the efficiency of rubber additives play an important role in extending the service life of rubber products.For this purpose,in this thesis,two kinds of chitosan-based macromolecular rubber additives COS-AO and COS-GMMP were synthesized,which had good antioxidative efficiency and were conducive to accelerate the vulcanization of styrene-butadiene rubber（SBR）.In addition,COS-GMMP also had a reinforcement effect on SBR.The effects of COS-AO and COS-GMMP on the properties of sbr were studied systematically.The main contents and results are as follows.Chitosan-based macromolecular rubber additives COS-AO was synthesized from chitosan（COS）and 3-（3,5-di-tert-butyl4-hydroxyphenyl）propionic acid（AO）.Its structure was confirmed by FTIR,¹H-NMR,¹³C-NMR,scanning electron microscope and elemental analysis.The effect of COS-AO on the sulfurization property of SBR vulcanizates was studied.The results showed that the optimum cure time(T_C90)of SBR with COS-AO was significantly decreased,demonstrating the good vulcanization acceleration effect of COS-AO.Fixing the content of COS-AO in SBR,vulcanization rate slowed down,crosslinking density decreased,and vulcanization activation energy increased with the decreasing of N-tert-butylbenzothiazole-2-sulphenamide（NS）/2,2’-dibenzothiazoledisulfde（DM）content.However,when the content of NS/DM decreased to 0.8/0.2 phr,it still could effectively accelerate the sulfur crosslinking reaction of SBR,which fully indicated the vulcanization acceleration effect of COS-AO.When the content of NS/DM was between 2/0.5 phr and 0.8/0.2 phr,the mechanical properties of SBR vulcanizate had no significant variation which were comparable as the control group,implying that the addition of COS-AO could reduce the usage of traditional vulcanization promotion system of NS/DM.The effect of COS-AO on the thermal-oxidative aging resistance of SBR was further studied.It was found that the maximum aging coefficient of SBR vulcanizates with COS-AO for 7 days was 0.43,and the longest oxidation induction time（OIT）was 41.2 min,which were significantly higher than those of SBR vulcanizates with antioxidant MB and AO,indicating that the thermal-oxidative aging resistance of COS-AO was obviously better than that of industrial antioxidant MB and corresponding small molecule antioxidant AO.Meanwhile,after extraction by methanol,the aging coefficient retention and OIT value of SBR vulcanizates with COS-AO were remarkably higher than those of SBR vulcanizates with antioxidant AO,indicating that COS-AO had better extraction resistance in styrene-butadiene rubber matrix and could play a long-term role of antioxidative aging.Another chitosan-based macromolecular rubber additives COS-GMMP was synthesized using chitosan（COS）,2-tert-butyl-6-（3-tert-butyl-2-hydroxy-5-methylphenyl）methyl-4-methylphenyl acrylate（GM）andβ-mercaptopropionic acid as raw materials.Its structure was confirmed by FTIR,¹H-NMR,¹³C-NMR and elemental analysis.The effect of COS-GMMP on properties of SBR was studied.It is found that COS-GMMP could accelerate the vulcanization of SBR,effectively facilitate the dispersion of SiO₂,and increase the crosslinking density of SBR vulcanizates.Compared with the blank sample,the tensile strength and tear strength of SBR vulcanizates with COS-GMMP were increased by 25.2%and 19.3%,respectively,and the rolling resistance was reduced by 29.5%,showing a better reinforcing effect.When the content of COS-GMMP was 3 phr（the content of GM structural unit was about 2 phr）,the effect of thermo-oxidative resistance and extraction resistance of COS-GMMP were obviously better than those of small molecule antioxidant GM,which the content is 2 phr.