Polycarbosilane is a kind of polymer compound, its main chain is composed of silicon and carbon atoms alternately, connected hydrogen or organic groups, molecular chain is linear or branched, polycarbosilane is an important compound in the precursor ceramic polymer, the precursor ceramic polymer is an emerging high-tech new material, mainly used in the preparation of silicon carbide series of high-tech ceramic materials. Among them, silicon carbide fiber is representative. Polycarbosilane is easy to be heated, and the silicon hydrogen bond in the molecular chain can be cross-linked, so it is widely used in the preparation of ceramics and matrix composites. Polycarbosilane and fiber are important precursors and strengthening and toughening materials of ceramic matrix composites, respectively. It has many advantages such as wear resistance, corrosion resistance, oxidation resistance, high temperature resistance, high conductivity and so on, and has become one of the promising high-performance materials at present.
Properties of polycarbosilane (PCS)
(1) Self-crosslinking
The ideal structure of PCS is linear or dendritic molecular chain, which contains active groups such as Si-H bond that can participate in crosslinking reaction, so it has good crosslinking property. In order to improve the ceramic yield of polycarbosilane pyrolysis, divinylbenzene is often used as a crosslinking agent before pyrolysis to effectively reduce the volatilization of small molecules in the pyrolysis process, and no oxygen is introduced in the process of self-crosslinking, so the pyrolysis materials have better properties.
(2) Can be modified processing
Polycarbosilane is easy to modify because it contains active groups, such as boron modification, aluminum modification, zirconium modification, etc., and the properties of pyrolysis products are also improved in different degrees.
