Preparation And Research On Properties Of Damping Silicone Rubber

Silicone rubber has been applied in aerospace and precision instruments due to its excellent and irreplaceable properties.However,its damping performance cannot meet stringent engineering standard at room temperature,which consequently requires modification to improve damping performance.In this paper,polysiloxane containing multiphenyl group as side group and polyborosiloxane with B-O-Si as backbone were synthesized.They were then added into silicone rubber with 30%phenyl and 0.3%vinyl respectively as addictive to improve damping performance of silicone rubber through volume effect,?-?interaction and weak bonding between boron atoms and oxygen atoms.The main contents of this paper are as follows:(1)Low-hydro silicone oil was prepared by high hydrogen-containing polysiloxane and octamethyl cyclotetrasiloxane(D4)through telomerization reaction.Then polysiloxane with triphenyl siloxy group,which was used as damping additive,was synthesized by dehydrogenation reaction of hydrogen-containing polysiloxane and triphenylsilanol The results showed that the tensile strength and tear strength of vulcanizate decreased when amount of damping additives increased.When triphenyl silica group ratio was 4.09%,the tan? increased at first and then decreased With increasing amount of additives.When adding amounts was 4 phr,the tan? of the silicone rubber increased with increasing triphenyl silica group(from 4.09%to 11.38%),though not obviously.(2)Vinyl silicone oil and phenyl vinyl silicone oil were preparaed by D4 and D4Vi DnPh,and then reacted with tetraphenylcyclopentadienone to synthesize tetraphenyl phenyl vinyl silicone oil/phenyl tetraphenyl phenyl vinyl silicone oil.The low conversion rate due to large volume of tetraphenyl phenyl groups accounted for lower tetraphenyl phenyl content than expected.The crosslinking density,tensile strength and tear strength of silicone rubber declined with the increase of damping additives content.The tan? increased with the increase of damping additive content,tetraphenyl phenyl group and phenyl group respectively,and had a slower decreasing rate with the rise in temperature.(3)Hydroxyl silicone oil was prepared by ring-opening polymerization of D4,with water as termination agent,which then reacted with boric acid for 2?3h at 150?to synthesize polyborosiloxane(PB).The results showed that the crosslinking density decreased with the increase of temperature.Compared with the blank rubber,vulcanizate adding PB had two degradation intervals.In low temperature interval(250?430?),degradation was mainly caused by condensation reaction between residual-OH,while degradation of chains was the primary reason in high temperature interval,the rate of which was less than that of blank rubber,and char yield at 800? increased from 50%to 61%.PB had little effect on the mechanical property of silicone rubber but improved tan?.