| Room temperature vulcanized(RTV)silicone rubber is non-toxic,tasteless,high elasticity,chemical inertness and delicate appearance as addition liquid silicone rubber,and it presents a variety of color when adds to different fillers.What is more,RTV silicone rubber is good feeling,environmental,room temperature vulcanizing and not easy to be poisoned compared with the common printing materials such as ink.Therefore,RTV silicone rubber as a potential printing material of textile field attracts more and more attentions.This paper reported the effects of the contents of catalyst,cross-linking agent and silane coupling agents on the curing times of silicone rubber.The effects of structure control agent and fumed silica contents on the mechanical properties of RTV silicone rubber were also studied by the assistance of fourier infrared analysis(FT-IR),scanning electron microscope(SEM),tensile test and so on.In this study,the mechanism related to RTV silicone rubber curing was discussed.Compared with dibutyltin dilaurate,dioctyldilauryltin as catalyst can prolong the track free and curing times of RTV silicone rubber.The catalyzing mechanism of dioctyldilauryltin was proposed and indicated that the effect of catalyst on RTV-2 silicone rubber curing is composed of crosslinking reaction under the action of catalyst and its moving in the liquid silicone rubber.The travel rate of catalyst molecule in silicone rubber is the main factor of RTV-2 silicone rubber curing.Especially,it is more serious when the catalytic content is low.The influences of crosslinking agents on RTV silicone rubber using tetraethoxysilane(TEOS)and tetrapropoxysilane were studied in this paper respectively.The results show that the crosslinking agent has much less influence on silicone rubber curing time than the catalyst.The curing times of silicone rubber are shorten at first and then prolong with the increasing of the crosslinking agent.Tetrapropoxysilane increases the track free and curing times of RTV silicone rubber in comparison of TEOS.The effects of KH-550 and KH-560,used to improve the bonding performance of RTV silicone rubber,on the curing time and other physical properties of silicone rubber were studied in this paper.The results show that KH-560 plays the crosslinking role during the course of the curing,which impacts the curing time of silicone rubber.However,KH-550 improves the hydrolyzing of the crosslinking agent,which provides more hydroxyl groups for the crosslinking reaction and greatly shortens the track free and curing times of silicone rubber.In the same system,the curing time of silicone rubber is shortened from 666min to 100min when the content of KH-550 is 0.89wt%.It is also found that the silicone rubber displays the matte and smooth surface when the content of KH-550 is excessive,which is associated with the small particles formed by the excessive KH-550 dissolving out to the surface of silicone rubber and performing self-condensation reaction.Using the hydroxyl silicone oil with low molecular weight and dihydroxydiphenylsilane as structure control agents,fumed silica as reinforcing filler,the mechanical properties of silicone rubber were studied.The results show that the tensile strength of silicone rubber modified by the hydroxyl silicone oil with low molecular weight and dihydroxydiphenylsilane respectively is 3.78MPa and 1.99MPa.Fumed silica modified by the hydroxyl silicone oil with low molecular weight have a better dispersion in the liquid silicone rubber rather than that modified by dihydroxydiphenylsilane.The tensile strength of silicone rubber enhances with the increase of fumed silica contents in the range from 15wt%to 30wt%.However,the elongation at break has the opposite change.The dihydroxydiphenylsilane has the better result in resisting structuring compared with the hydroxyl silicone oil with low molecular weight. |
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