| Silicone rubber exhibits unique properties such as superior temperature, weather resistance, ozone resistance, good electrical insulation properties, and so on. Silicone rubber is an important and essential polymer material in the national economy, and is widely used in many fieids. It has significant theory and application to prepare new functional silicone rubber and study new curing system. In this dissertation, new type radiation resistance silicone was prepared and studied. We proposed two easy and effective methods to improve the radiation resistance of silicone rubber. On the other hand new curing system was studied by using polysiloxane containing chloropropyl groups as a base gum and polyamine compound as a crosslinker.In this dissertation, rare earth oxides (yttrium oxide, cerium oxide and gadolinium oxide) were used as the radiation resistance additives for silicone rubber. The effects on radiation resistance of both high-temperature vulcanization (HTV) silicone rubber and room-temperature vulcanization (RTV) silicone rubber were investigated by using single rare earth oxide, mixture of rare earth oxides or mixture of rare earth oxide and traditional radiation resistance additive (barium sulfate) as the radiation resistance additives, respectively. The mechanical properties of the silicone rubber before and after irradiation showed that rare earth oxides could effectively improve the radiation resistance of silicone rubber. And when the amount used of rare earth oxides was 10-20 phr, the prepared silicone rubbers had fine radiation resistance. This is an easy and economical method to improve the radiation resistance of silicone rubber.Three kinds of silane with condensed ring group, tetraphenyl-phenyltriethoxysilane (TPHPHS), acenaphthenephenyltriethoxysilane (APHS), phenanthrenephenyltriethoxysilane (PPHS), were synthesized by Diels-Alder reaction of tetraphenylcyclopentadienone, acenaphthenecyclone and benzophenanthrenecyclone with vinyltriethoxysilane. The fumed silica was treated by the silane with condensed ring group. Three kinds of treateted fumed silica (TPHTS, APHTS, and PPHTS) were obtained. The treated fumed silica was characterized by N2 adsorption, diffuse reflectance ultraviolet-visible spectra (DRUVS) and titration. The results showed that the condensed ring groups were introduced to the silica surface. The treating process has two significant effects, that is, on one hand the condensed ring groups were grafted onto the silica surface to improve the radiation resistance, on the other hand the excrescent hydroxyls on the surface of silica were treated off to avoid the phenomena of crepe hardening. The treated fumed silica was used as reinforcing filler to prepare new radiation resistance silicone rubber. The silicone rubber obtained had fine radiation resistance. After 500 kGy irradiation in air, for sample reinforced by 50 phr TPHTS the tensile strength decreased from 8.84 MPa to 5.71 MPa, for sample reinforced by 50 phr APHTS the tensile strength decreased from 8.50 MPa to 6.03 MPa, and for sample reinforced by 50 phr PPHTS the tensile strength decreased from 8.63 MPa to 6.31 MPa.Only a little part of silane coupling agent with condensed ring group can react with the silanol group on the silica surface because of the large steric hindrance of condensed ring group. And there are still too many silanol groups on the surface of fumed silica. So hexamethyldisilazane was used to treat fumed silica (TPHTS, APHTS, and PPHTS) sequentially to react with the residual silanol groups. Three kinds of treated fumed silica (TPHMTS, APHMTS, and PPHMTS) were obtained. The treated fumed silica was used as reinforcing filler to prepare new radiation resistance silicone rubber. The silicone rubber obtained not only had excellent mechanical properties but also had fine radiation resistance. After 500 kGy irradiation in air, for sample reinforced by 60 phr TPHMTS the tensile strength decreased from 10.16 MPa to 7.26 MPa, for sample reinforced by 60 phr APHMTS the tensile strength decreased from 8.71 MPa to 7.12 MPa, and for sample reinforced by 60 phr PPHMTS the tensile strength decreased from 9.06 MPa to 6.01 MPa.Three kinds of treated fumed silica (MPHTS, DPHTS, and PHTS) were prepared with methylphenyldimethoxysilane, diphenyldiethoxysilane, and phenyltriethoxysilane as treating agents, respectively, and characterized by N2 adsorption, diffuse reflectance ultraviolet-visible spectra (DRUVS), titration and elemental analyzer. The results showed that compared with untreated silica there were less surface hydroxyl groups retained on the treated silica, and the phenyl groups were introduced onto the silica surface. The treated silica was used as reinforcing filler to prepare new radiation resistance silicone rubber. The mechanical properties and the average molecular weight between crosslinking points (Me) of the silicone rubber were measured before and after irradiation. It was found that the treated fumed silica not only effectively improved the radiation resistance of silicone rubber but also had excellent reinforcing effect on silicone rubber. After 500 kGy irradiation in air, for sample reinforced by 60 phr MPHTS the tensile strength decreased from 8.46 MPa to 5.53 MPa, for sample reinforced by 60 phr DPHTS the tensile strength decreased from 8.04 MPa to 5.08 MPa, and for sample reinforced by 60 phr PPHMTS the tensile strength decreased from 9.59 MPa to 4.82 MPa.Choropropylmethycyclosiloxane mixtures were synthesized by the hydrolysis of choropropylmethyldiethoxysiloxane and dimethyldiethoxysiloxane. Methyl-chloropropylpolysiloxane was synthesized by ring-opening copolymerization of octamethylcyclotetrasiloxane and choropropylmethycyclosiloxane mixtures. A new type of curing system for silicone rubber was investigated by using polysiloxane containing chloropropyl groups as a base gum, polyamine (tetraethylene pentamine, aminopropyl methy silicone oil and 3-(2-aminoethylamino) propyl methy silicone oil) as a crosslinker and zinc oxide as a acid absorbent. Effects of various factors on the silicone rubber were investigated in detail. Better technical conditions were determined and silicone rubbers with fine mechanical properties were obtained. Using tetraethylene pentamine as a crosslinker, the tensile strength, tear strength, and elongation at break of the silicone rubber reach 10.24 MPa,39.06 kN/m,920%, respectively. Using aminopropyl methy silicone oil as a crosslinker, the tensile strength, tear strength, and elongation at break of the silicone rubber reach 9.81 MPa, 41.14 kN/m,1504%, respectively. Using 3-(2-aminoethylamino) propyl methy silicone oil as a crosslinker, the tensile strength, tear strength, and elongation at break of the silicone rubber reach 9.30 MPa,38.63 kN/m,1345%, respectively. |
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