Synthesis Of Phenyl Silicone Rubber And Study On Properties Of Composite Materials

Silicone rubber is an important class of polymer materials,with silicon-oxygen bonds as the main chain and strong molecular chain designability,which has been widely used in aerospace,chemical,agricultural,medical and health fields.Under certain extreme operating conditions,rubber materials are required to have high damping performance,high and low temperature resistance,and radiation resistance.Traditional methyl vinyl silicone rubber unable to meet these demands.In this topic,high-phenyl content silicone rubber was synthesized by introducing phenyl chain links and increasing molecular weight,and phenyl silicone rubber composite materials were prepared by adding functional components such as nano-silica,titanium dioxide or nano-carbon materials,and the composite materials were systematically studied.The damping performance,radiation resistance and so on,which has provided technical support for high-performance silicone rubber materials in extreme areas.In chapter 2,diphenyl silicone rubber(DPVMQ)with a phenyl link of 5%to 25%was synthesized by using anionic polymerization method.Under the catalytic effect of KOH,we obtain its number average molecular weight is between 220,000 and 350,000 DPVMQ composite material was prepared by adding white carbon black and increasing the reaction temperature and giving sufficient reaction time.The research reveals that with the increase of phenyl link content,the loss factor increased from 0.15 to 0.85,the tensile strength increased first and then decreased and highest at 5%benzene chain content with 11.6 MPa.Therefore,the radiation resistance of DPVMQ was greatly improved and the DPVMQ with 20%phenyl chain links still had a tensile strength of 6.7 MPa after being irradiated with 300kGy gamma rays.The tensile strength retention rate can be up to 88.9%.In chapter 3,A series of DPVMQ composite materials were prepared by using DPVMQ with a phenyl chain content of 10%to 20%as a base glue and adding nano fillers(Nano-TiO2,CB,CNT).The research indicates that under the double protection of phenyl and functional filler,the radiation resistance of silicone rubber is greatly improved and the degree of improvement of the radiation resistance of the material by phenyl is higher than that of the filler.The optimal value is DPVMQ composite with 20%phenyl chain content and 5 phr Nano-TiO2 added.After 300kGy gamma irradiation,the tensile strength is 7.6 MPa and the retention rate is 98.70%.This work provides new ideas for the research and development of phenyl silicone rubber materials used in high-irradiation environments.In chapter 4,Monophenyl silicone rubber(MPVMQ)with a phenyl chain content of 5%to 25%was synthesized with a number average molecular weight of 250,000 to 350,000.In addition,the MPVMQ composite material was prepared by adding the white carbon.As the content of monophenyl chain links increases,the loss factor show a slowly increases from 0.7 to 0.8 and the tensile strength tends to first rises then falls and the highest at 20%monophenyl chain links content,which is 10.0 MPa.The irradiation resistance of MPVMQ increases with the increase of the content of monophenyl links.The MPVMQ of 20%monophenyl links maintained a tensile strength of 5.4 MPa after irradiation and the retention rate is 54%.Compared with DPVMQ,the increase of phenyl chain content makes DPVMQ and MPVMQ show similar rules in terms of mechanical properties,damping performance and radiation resistance.However,DPVMQ performance more superior merits than MPVMQ due to the difference in structure and actual phenyl content in the system.