Study On Structure And Properties Of Liquid Polysulfide Rubber And Modified Benzoxazine Resin

Liquid polysulfide rubber was the earliest synthesized liquid rubber in the world. Due to its superior performance, the simple process and simplifying construction, it is durable and wide used in each industrial sector. With the development of technology and research, more and more liquid polysulfide rubber is being used. As a new kind of engineering thermoset, benzoxazine resin took more attention at home and abroad. It is an important way to make phenolic resin become engineering plastics of high performance. To improve the comprehensive properties is an important research aspect of modification of benzoxazine resin.This thesis focused on the sturcture and properties of liquid polysulfide rubber, and studied on benzoxazine resin modified by liquid polysulfide rubber, and traditional benzoxazine modified by new benzoxazine which were first synthesized.In order to find the influencing factors of chroma of national polysulfide rubber, we analysed liquid polysulfide rubber with many modern testing means. The means we used included FTIR、GPC、Uv、 ICP、TXRF and GC-MS. The impurity was detected by ultraviolet measurements of liquid polysulfide rubber. Through analysing the content of metal elements in liquid polysulfide rubber, the combination of Fe and S was initially defined as an influencing factor of chroma. Another factor was found by GC-MS as a kind of cyclic sulfide.For improving the properties of benzoxazine resin, we studied benzoxazine resin modified by liquid polysulfide rubber. Different proportion of liquid polysulfide rubber and benzoxazine were blended and cured during the experiment. The structure, thermal property, and mechanical properties of the modified resin were characterized by DSC, FTIR, DMA, TG, and impact strength methods. The results show that the mechanical properties and thermal property of the modified resin have been improved in different degree. The following conclusions can be found according to experiment:the optimal ratio of benzoxazine to liquid polysulfide rubber is:benzoxazine resin100portions(mass) and liquid polysulfide rubber5portions. At that ratio, the toughness and thermal stability of the modified resin both improve compared with pure resin, and the glass transition temperature of the modified resin changed little, the comprehensive properties of the composites are the best.In addition, Three kinds of new benzoxazine were first synthesized with eugenol、guaiacol and cardanol which could react with decamethylenediamine. Testing and characterization of products has been taken. All the materials come from natural products, this has important significance in effective utilization of natural energy and the development of environment-friendly material. The new benzoxazine was blended with traditional benzoxazine, and the toughness of the cured composite was improved, and the highest improvement of the impact strength was3times.