Preparation Of Chlorosulfonated Polyethylene By Liquid-Solid Phase Method And Characterization Of Structure And Properties

High performance chlorosulfonated polyethylene(CSM)was prepared by liquid-solid bulk method.In the absence of any organic solvent,liquid sulfonyl chloride is used instead of gaseous sulfur dioxide,which greatly improves the utilization of sulfur dioxide,simplifies the production process and meets the requirements of environmental protection.In order to improve the distribution uniformity of sulfur atoms in molecular chains,we adopted the process of coating liquid sulfonyl chloride with oil(DOP),which effectively increased the thermal decomposition temperature of sulfonyl chloride and improved the distribution of chlorosulfonyl groups in molecular chains,thus greatly improving the properties of products.The feasibility of liquid-solid preparation of chlorosulfonated polyethylene was proved by FT-IR,1H-NMR and GPC,and the basic structure was analyzed.The process of preparation was discussed,and the optimal chlorine inflow was determined.When the degree of pre-chlorination is 10%,the chlorine distribution of the product is the best and the mechanical properties are the best.The selection and proportion of raw materials are quantitatively analyzed,and the optimum ratio of raw materials is determined.Chlorosulfonated polyethylene with different chlorine and sulfur contents was prepared by liquid-solid method,and its properties were characterized.It was found that the higher the chlorine content in the molecular chain,the worse the resilience andthe smaller the compression permanent deformation;Tg increased with the increase of the polar chlorine atom content,while the tensile strength and elongation at break had little relationship with the chlorine content.The crosslinking density decreases with the increase of sulfur content;the hardness and tensile strength increase with the increase of sulfur content,while the elongation at break decreases;TG tests show that the thermal decomposition process can be divided into three stages: the removal of chlorosulfonyl groups on the molecular chain,the removal of chlorine atoms on the molecular chain and the degradation reaction.Comparing the structures and properties of CSM prepared by liquid-solid method with CSM3305 prepared by solution method,it was found that the chlorine distribution in CSM molecular chains prepared by liquid-solid method was more uniform and random,the molecular weight was larger,the molecular weight distribution was narrower,and the crosslinking density was higher,the molecular weight between vulcanization crosslinking points was smaller,so the CSM molecular chains prepared by liquid-solid method had better mechanical properties.