Preparation Of High-cis Hydroxyl-terminated Polybutadiene Elastomer And Study On Self-healing Properties

Hydroxy-terminated polybutadiene,referred to as HTPB in English,is a new type of liquid rubber,it has excellent low temperature performance,hydrolytic stability and heat resistance,and has great applications in tire rubber products,adhesives and coatings.HTPB has the following advantages:(1)It is liquid at room temperature,so it can be cast during the processing process,which is easy to realize the automation and continuity of the process and save a lot of manpower.(2)Due to its hydroxyl groups at both ends,it can smoothly react with isocyanate groups to form polyurethane coatings and adhesives.(3)HTPB type polyurethane also uses white carbon black,zinc white,glass fiber,etc.as a reinforcing agent to improve performance.However,HTPB has the problems of high price,low aging resistance and low temperature resistance.The physical and chemical properties of HTPB are closely related to the microstructure.The HTPB contains cis-1,4,trans-1,4 and 1,2-vinyl structures,the higher the cis-1,4 content,the lower the glass transition temperature and the better the mechanical properties.Due to the excellent mechanical properties of high cis-1,4 HTPB,the synthesis of high-cis HTPB is particularly important.HTPB can be used with curing agent,chain extender etc.to prepare strong stretch polyurethane elastomer.So far,the research on self-healing technology of flexible materials in scientific research field mainly focuses on simple polymer materials such as polyvinyl alcohol and polyacrylic acid,which all have the problems of low tensile strength and strain,long repair time and low self-healing rate,and fail to meet the requirements of mechanical properties and self-healing conditions of flexible materials.In this paper,high cis HTPB is mainly prepared by oxidative cracking method,and its cis-1,4 content reaches 97.4%.Synthetic high cis-1,4 HTPB is used as raw material,and toluene diisocyanate(TDI)is used as curing agent,1,4-Butanediol(BDO)is the chain extender,dibutyltin dilaurate(T-12)is the catalyst,synthesized polyurethane elastomer.Infrared spectroscopy,thermogravimetric analyzer,electronic universal tensile analyzer,etc.were used to analyze its performance.The result shows that when the curing parameter is 1.3,the catalyst dosage is 2%,the BDO content is 7%,and the curing temperature is 60?,the mechanical properties of the elastomer are optimal.Under the optimized conditions,the elongation at break was 997.33%,the tensile strength was 1.83 MPa,tensile modulus is 4.65 MPa,toughness is 11.71 MJ/m3.The thermal decomposition temperature is 118?,and the elastomer has the highest thermal weight loss rate at 295? and 452?.and it had good thermal properties.After successfully synthesizing polyurethane elastomers with excellent mechanical properties,the hydroxy-carboxy-terminated polybutadiene(HCTPB)was synthesizedfrom the successfully prepared high cis-1,4 HTPB,and the HCTPB and the Fe3+ was introduced into the curing system,the crosslinking network formed by the complexation of Fe3+ and HCTPB has greatly improved the self-healing properties of the elastomer.the result shows that the tensile strength of the prepared spline is 5.2 MPa when the proportion of HCTPB is 6%,The elongation at break is 877.8%,tensile modulus is 9.43 MPa,toughness is 28.88 MJ/m3,and the self-healing efficiency can reach 92% after healing at 80? for 10 hours after cutting.