| Room temperature vulcanization silicone rubber is widely used in electronic,electrical,construction,medical and other fields because of its unique structure and excellent performance.However,the unmodified silicone rubber has poor mechanical properties and thus limits its practical application due to the flexible molecular chain.In this study,Rosin modified organosilane and rosin grafted polysiloxane were prepared respectively using natural resources rosin and its modified products to make rosin based silicone rubber with high mechanical and thermal properties.And then the hydrogenated phenanthrene ring structure of rosin was located in the structure of silicone rubber.Studying the influence law of the structure of rosin based silicone rubber on its properties.Rosin modified aminopropyltriethoxysilane?RA?was prepared from rosin.RA was used as a cross-linking agent to prepare rosin based room temperature vulcanized?RTV?silicone rubber with hydrogenated phenanthrene ring pendant groups.The rosin modified silicone rubber was tested by universal testing machine,thermal stability analysis and other instruments.The results showed that the mechanical and thermal properties of rosin modified silicone rubber were obviously improved.Compared with unmodified silicone rubber,the tensile strength and elongation at break of rosin modified silicone rubber were increased by 11%and84%,respectively.The greatest rate of mass loss temperature and the residual rate at 800 ? increased by 201 ? and 4.17%.However,the actual mechanical strength was still small,and the value was only 0.51 MPa,which was caused by the low crosslinking density of silicon rubber.Different content of rosin modified silicone rubber were prepared by using the mixture of rosin modified aminopropyltriethoxysilane and TEOS as crosslinking agent as which the amount of active group of oxyethyl groups are fixed.The effect of RA modified silicone rubber structure on its mechanical and thermal properties was investigated.The results showed that compared with SRTE-1 unmodified silicone rubber,the 10%mass loss temperature and the greatest rate of mass loss temperature of SRRA silicone rubber increased by 76 ? and 253 ?,respectively.In addition,the significant improvement of tensile strength and elongation at break of SRRA-3 silicone rubber was 1.25 MPa and 355%.Although the RA are well-dispersed in the RTV silicone rubber,microphase separation that caused by the aggregation of RA occurs in it,which was evident in the SEM images and RDS analysis.Butane modified silicone rubber as reference material was prepared.It was verified that the introduction of rosin with hydrogenated phenanthrene rings into silicone rubber would increase the crosslinking density and chain entanglement.These behaviors play a key role in mechanical and thermal properties of silicone rubber.Acrylpimaric acid modified aminopropyltriethoxysilane?AA?was prepared by using rosin as raw material.Acrylpimaric acid modified silicone rubber SRAA with hydrogenated phenanthrene ring in crosslinking network skeleton structure was prepared by using AA and tetraethoxysilane?TEOS?as a crosslinking agent.The results showed that the mechanical and thermal properties of acrylpimaric acid modified silicon rubber increased significantly.The temperature of 10%mass loss and the greatest rate mass loss temperature reached 465 ? and564 ?,respectively.In addition,the tensile strength and elongation at break of the SRAA-3silicone rubber were 1.45 MPa and 283%,respectively.Because the chemical introduction of rosin with strong rigid hydrogenated phenanthrene ring into crosslinked network skeleton structure of silicone rubber,the increase of polysiloxane chain entanglement and crosslinking density and the enhance of the acting force between the polysiloxane chains.Bisphenol A modified silicone rubber SRDA-1 as a contrast experiment was prepared by using commercial product of bisphenol A two glycidyl ether with similar structure of AA.It is found that the mechanical and thermal properties of SRAA-3 silicone rubber are better than that of bisphenol A modified silicone rubber.The tensile strength and the elongation at break of SRDA-1silicone rubber are 1.05 MPa and 280%.Fumaropimaric acid modified aminopropyltriethoxysilane?FA?was prepared by using rosin as raw material.Fumaropimaric acid modified silicone rubber?SRFA?with hydrogenated phenanthrene ring into crosslinking skeleton network was prepared by using FA and TEOS as a crosslinking agent.It was found that the FA modified silicone rubber showed better thermal and mechanical properties.The tensile strength and elongation at break of modified silicone rubber SRFA-3 containing 12 wt%FA reached 1.22 MPa and 315%,respectively and the crosslinking density was 2.01×10-4 mol·cm-3.With the increase of FA,the storage modulus and glass transition temperature of the silicone rubber increased slightly.And the 100%modulus,density and Shore hardness of the silicone rubber also increased.Rosin glycidyl ester and hydroxyl terminated amino polysiloxane were prepared respectively.Rosin grafted polysiloxane?RGSO?was prepared by the reaction of glycidyl ester of rosin acid and hydroxyl terminated amino polydimethylsiloxane through further reaction.It was found that the molecular weight of RGSO and the degree of entanglement of polysiloxane chains increased.The number average molecular weight and apparent viscosity increased from11765?HTAS?to 14472 Da?RGSO-4?,and from 7?HTAS?to 18980 Pa s?RGSO-4?,respectively.Rosin grafted silicone rubber?SRER?were synthesized using rosin modified polysiloxane as primary polymers through condensation reaction.It was found that rosin modified silicone rubber possesses good mechanical and thermal properties.Compared with unmodified silicone rubber,the tensile strength and elongation at break of SRER-3 were 1.07MPa and 402%,respectively,and increased by 138%and 113%,respectively.The temperature of 10%mass loss and the greatest rate mass loss temperature increased by 66 ? and 177 ?,respectively.These were attributed to the modified silicone rubber with hydrogenated phenanthrene ring structure,and the increase of chain entanglement and crosslinking density. |
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