Synthesis And Properties Of Epoxidated Phenyl Silicone Rubber

The molecular chain of silicone rubber is composed of silicon atoms and oxygen atoms alternately,and has excellent resistance to high and low temperatures,aging resistance,electrical properties and the like.At the same time,through the molecular design,the introduction of different pendant group substituent groups can impart different characteristics such as high damping,radiation resistance and flame retardancy to silicone rubber,and is widely used in aerospace,chemical,agricultural and medical health.Some extreme conditions impose high temperature resistance,radiation resistance,high damping and other performance requirements on rubber materials,the author studied the effects of different solvent,temperature and time process parameters,and obtained epoxidized phenyl silicone rubber.(EMVPQ)safe and efficient preparation process;a series of EMVPQs were synthesized by molecular design and anion ring-opening polymerization method.The effects of epoxidation degree and phenyl content on rubber properties were studied.The carbon black was reinforced,and the EMVPQ composite was prepared.The high and low temperature resistance,damping performance,radiation resistance and oil resistance of the material were studied.The main findings are as follows:(1)A new process for epoxidation of silicone rubber was obtained:chlorobenzene for solvent,ratio of peroxyacid to double bond of 1.3,concentration of silicone rubber of 50 g/L,reaction temperature of 55?,reaction time of 72 h;final epoxy The conversion rate is higher than 90%.Compared with the original process,the reaction time is shortened by 25%,the silicone rubber concentration is increased by 66.7%,and the reaction efficiency is twice that of the original process;compared with chloroform,the solvent has a high boiling point,low toxicity,and low dosage.The reaction process is safer.(2)A phenyl silicone rubber(MVPQ)with a phenyl content of 5%to 25%was synthesized,and a 5%-20%phenyl content and a 15%epoxy content of EMVPQ were prepared by a new epoxidation process.The oxygen conversion rate is between 81%and 94%.Compared with MVPQ,the number average molecular weight of EMVPQ will be reduced by about 40,000,between 12 and 170,000,and the polydispersity index is 2.27 to 2.66.Compared with MVPQ with the same phenyl content,EMVPQ has a Tg increase of about 10?,which improves heat resistance to some extent.The EMVPQ composites were prepared by silica black.It was found that with the increase of phenyl content,the damping loss peak of the material moved to the high temperature direction and the effective damping temperature range was broadened,and the oil resistance and mechanical properties were reduced.The phenyl content was 20%of EMVPQ composites have the best radiation resistance.Taken together,the EMVPQ composite with a 10%phenyl content has the best performance.(3)Using epoxidation new process,EMVPQ with 10%phenyl content and 10%-30%epoxy content was prepared,and its epoxy conversion rate was between 86%and 93%.Compared with MVPQ before epoxy modification,the epoxide content of EMVPQ increased by 10?23?.A white carbon black reinforced EMVPQ composite was also prepared.The study found that when the epoxide was increased from 0%to 30%,the loss factor of the composite increased from 0.5 to 0.72,and the loss peak shifted to about 22?.The 30%epoxy EMVPQ composite exhibits the best heat resistance and oil resistance,but the mechanical properties are relatively poor.From the practical application of EMVPQ composites,the epoxy content is suitable between 10%and 20%.(4)Comparing the performance of the commercially available MVPQ(phenyl content of 10%)and the composite EMVPQ(phenyl content of 10%,epoxide 15%)composite,found that the loss factor of EMVPQ is 0.64,loss peak Moving to high temperature,the damping performance is better;after 100?,immersion in standard oil No.3 for 72 h,or after total irradiation dose of 100 kGy,EMVPQ maintains higher mechanical properties,exhibits better oil resistance and resistance to radiation.Photo performance;heat resistance does not change much.