A polysilazane with excellent spinning performance and its preparation and melt spinning

Abstract

The invention discloses a polysilazane with excellent spinning performance and its preparation and melt spinning. The main chain of the polysilazane prepared in the present invention is a line-ring structure including a four-membered ring and a six-membered ring. The preparation process includes: component optimization of oligomers prepared by ammonolysis reaction method, stepwise thermal polymerization of oligomers and Melt spinning; the molar ratio of the reaction raw materials is 1:1-1.9:1 methylhydrogendichlorosilane and dimethyldichlorosilane, the reaction solvent is n-hexane, and the volume ratio of n-hexane and raw materials is 4:1 , the silazane oligomer was obtained through ammonolysis reaction, and the polysilazane precursor with excellent spinning performance was obtained through the gradual thermal polymerization of the oligomer; under the condition of 90-120°C, polysilazane was realized by melt spinning Continuous spinning of alkane fibers. The polymerization device of the invention is simple, no external activator is needed in the polymerization process, the reaction process is easy to control, the molecular structure of the prepared polysilazane can be designed, the spinning performance is excellent, and low-temperature melt spinning of continuous fibers can be realized.

Description

technical field [0001] The invention belongs to the field of fiber preparation, and in particular relates to a polysilazane with excellent spinning performance and its preparation and melt spinning. Background technique [0002] Silicon nitride ceramic fibers have excellent properties such as high melting point, good high-temperature mechanical properties, small thermal expansion coefficient, good dielectric properties, low density, and strong oxidation resistance, and have broad application prospects in the field of ceramic matrix composites. Precursor conversion method is the main preparation method of silicon nitride ceramic fiber. The preparation of polysilazane precursors with excellent structural properties and spinning performance is one of the keys to the precursor conversion method, and has attracted the attention of researchers at home and abroad. [0003] Patent CN 104817701A discloses a thermoplastic polysilazane prepared by using methylhydrogendichlorosilane an...

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Problems solved by technology

The polymerization temperature of this method is 300-480°C, and the thermal polymerization reaction is carried out in a pyrolysis column. The pyrolysis temperature is high and the molecular structure is difficult to control.

[0004] It can be found that the following problems exist in the field of polysilazane fiber preparation at present: an activator or catalyst needs to be added during the polymerization process, which increases the difficulty of controlling the degree of polymerization, and at the same time, it is easy to introduce heterogeneous elements and reduce the purity of the product; the polymerization temperature is too high during the polymerization process , the polymerization time is too long, resulting in low polymerization efficiency and increased polymerization cost; the polymerization device is complicated, and a high-temperature cracking column is required, which greatly increases the polymerization cost and the complexity of the preparation process

There are defects in the structure of polysilazane, which leads to the high brittleness of the prepared polysilazane fiber and cannot be wound

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