Polysilazane with excellent spinning performance and preparation and melt spinning thereof

Abstract

The invention discloses polysilazane with excellent spinning performance and preparation and melt spinning thereof. The main chain of the polysilazane is of a linear-cyclic structure containing a four-membered ring and a six-membered ring. The preparation process comprises the following steps: optimizing components of an oligomer prepared by an ammonolysis reaction method, and performing gradual thermal polymerization and melt spinning on the oligomer, wherein the molar ratio of the methyl hydrogen dichlorosilane to the dimethyl dichlorosilane is 1: 1-1.9: 1, the reaction solvent is n-hexane,the volume ratio of the n-hexane to the raw materials is 4: 1; obtaining a silazane oligomer through ammonolysis reaction, and obtaining a polysilazane precursor with excellent spinning performance through gradual thermal polymerization of the oligomer; and realizing continuous spinning of the polysilazane fibers through melt spinning u nder the condition of 90-120 DEG C. The polymerization deviceis simple, the activating agent does not need to be additionally added in the polymerization process, the reaction process is easy to control, the molecular structure of the prepared polysilazane canbe designed, the spinning performance is excellent, and low-temperature melt spinning of continuous fibers can be achieved.

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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