Preparation And Property Research Of High Ultraviolet Transmittance Silicone Rubber

As the rapid development of photoelectron, optical instruments and military fields, the application of high-UV-transmission materials were broader than before. However, on the consideration of cost, preparation and application effect, the application of traditional special inorganic-glass materials were limited. Research of polymer as the substitute materials became hot focus during the past years.In this work, octavinyl polyhedral oligomeric silsesquioxane(POSS) was grafted to the PHMS(crosslinker) by the method of solution-grafting. Finally, POSS can be grafted to silicone rubber matrix by the reaction of POSS-contained crosslinker and vinyl-contained oil. The curing process was mesured by differential scanning calorimeter, the machanical properties of modified silicone rubber was tested by durometer and tension creep testing machines, the thermostability and UV transmittance were investigated by TGA and ultraviolet?visible spectrophotometer, respectively. The result indicated that the induction period was extended and the initial cure temperature as well as end cure temperature was increased as the rise of POSS additive amounts. The combination property presents the optimal when the POSS additive amount is 0.5 wt%(tensile strength is 6.97 MPa, elongation at break is 402.42%, crosslink density is 5.33?10-4 mol/cm-3, UV transmission at 351 nm is 88.60%, and the thermal decomposition temperature increased 89.40 oC).In comparision with the modification of modifier, a new high-ultraviolet(UV)-transmission silicone-resin polymeric material was prepared via curing during hydrosilylation of tetramethyltetravinylcyclotetrasiloxane with tetramethylcyclotetrasiloxane by a liquid-surface supernatant method, using a stepwise heating program to avoid spontaneous combustion of the reaction mixture. The relationships were investigated in detail between reactive groups, cross-linking density, mechanical and UV-transmission properties. For this purpose, UV transmittance and dynamic mechanical properties, respectively, of the highly cross-linked silicone resin were measured with UV?visible spectrophotometry and dynamic mechanical thermal analysis. In addition, surface roughness was evaluated with an atomic force microscope as well as an interferometer. The curing process was monitored by fourier transform infrared spectroscopy and rotational rheometry. The cyclic silicone oils were compared with linear ones in structure and product properties. The results indicated that stepwise temperature control during curing process was particularly indispensible due to the presence of active Si?H bonds, and that the highly cross-linked silicone resin of high modulus, high UV transmittance(92.70%) and low surface-roughness was largely homogeneous in cross-linking points distribution.