High temperature high pressure synthesis method for polycarbosilane

Abstract

The invention provides a high temperature high pressure synthesis method for polycarbosilane which comprises the steps of, (1) loading small molecular PCS or LPS whose PDMS or average molecular weight is less than 2000 into hot pressing kettle, evacuating and replacing gas in the kettle with high purity nitrogen, charging 0.1-5Mpa of N2 and sealing, elevating the temperature to 430-490 deg. C, reacting time being 0.5-10 hours, (3) dissolving the crude product with xylene, filtering, and proceeding vacuum distillation to the filter liquor at 330-380 deg. C, finally cooling down to obtain the resin form product.

Description

technical field [0001] The invention relates to a synthesis method of polycarbosilane, in particular to a synthesis method of polycarbosilane under high temperature and high pressure. Background technique [0002] At present, the preparation method of SiC fiber is mainly the transformation method of organic precursor. This method includes the synthesis of organic precursor polycarbosilane (Polycarbosilane, PCS), melt spinning, non-melting and high-temperature firing and other processes. PCS is the key material for the preparation of SiC fibers by the conversion method of organic precursors. The synthesis of PCS precursors is the basis of all research work. Its composition, structure and key physical and chemical properties play a very important role in determining the performance of SiC fibers. The performance of the PCS precursor not only directly affects the melt spinning process and the quality of the precursor, but also affects the non-melting ...

AI Technical Summary

Problems solved by technology

Research in the past 20 years has shown that the synthesis time of this method is long (>48h), the yield of synthetic PCS is low, and the synthesized PCS has problems such as low molecular weight, low softening point, and low Si-H bond content.

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