Synthesis And Properties Of Hydroxyl-erminated Liquid Fluorosilicone Elastomer With Room-Temperature Vulcanization

The influence of agitation model, catalyst and chain transfer agent on the properties of liquid fluorosilicone elastomer was system studied, and the raw rubber post-treatment process was improved, making it possible to successfully prepare hydroxyl-terminated liquid fluorosilicone elastomer cable of curing at room temperature. The microstructure, component and the main physical properties of the obtained fluorosilicone elastomer were analyzed and tested in detail. The investigation of the properties by customer was also performed.The studies exhibited that the way of agitation had a very important role on the microstructure and properties of the hydroxyl-terminated liquid fluorosilicone elastomer cable of curing at room temperature. The experimental results showed that ill-defined elastomer with broad molecular weight distribution was produced in bulk polymerization system at 110~130℃ agitated by nitrogen bubble, leading to bad process properties. This is mainly due to the difficulties in both heat transfer and release of small molecular weight substances produced during the course of the condensation polymerization with nitrogen as agitation, resulting in self-activated polymerization, especially when the viscosity of the polymerization system grew high. Therefore, the rubber was prepared through the new process with mechanical agitation. It was found that the problems mentioned above, such as the heat transfer, the release of small molecular weight substances were successfully solved. As a result, well-defined polymer with narrow polydispersity and improved process property was prepared.The problems such as the ill-controlled molecular weight, depolymerization after long-term placement were well solved through selection of catalyst, using of chain transfer agent and improvement of post-treatment. The equality of the raw rubber, the curing property and the placement stability were greatly improved.The microstructure, molecular weight as well as the polydispersity were characterized and analyzed by FT-IR, ~1H NMR and GPC.Customer conducted the vulcanization formula investigation and properties determination. The results demonstrated that main properties of this product reached the requirements as sealant application.