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High-molecular-weight and high-linearity polycarbosilane and preparation method and application thereof

A technology of polycarbosilane and high molecular weight, which is applied in the field of polycarbosilane with high molecular weight and high linearity and its preparation, can solve the problems of low softening point, low strength and low yield of silicon carbide fibers, and achieve good textile performance, The effect of narrow molecular distribution and simple process

Active Publication Date: 2019-05-17
江西信达航科新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the current yield of synthesizing PCS precursors is low, and the synthesis cost of polycarbosilane is high; in addition, the molecular weight of PCS is difficult to increase, and the softening point is low, which leads to the low strength and molecular branching degree of the silicon carbide fibers prepared therefrom. Seriously, the spinnability of silicon carbide fiber is poor

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0022] The present invention provides a kind of preparation method of polycarbosilane with high molecular weight and high linearity, comprising the following steps:

[0023] S1: Put polydimethylsilane (PDMS) in a distillation device, carry out distillation under the protection of high-purity inert gas, and collect fractions at 102-105°C; wherein, the inert gas is nitrogen or argon, and the gas flow rate is 60-100°C. 100mL / min.

[0024] S2: Put the fraction in a three-necked flask equipped with a cracking column, a condenser and a receiving device, pass in an inert gas, raise the temperature to 400-420°C at a rate of 1-2°C / min and keep it warm for 24-30h, then cool naturally to room temperature, Take it out to get silane oligomers. Wherein, the inert gas is nitrogen or argon, and the gas flow rate is 150-200 mL / min.

[0025] S3: Dissolve the silane oligomer in xylene, place in a fume hood and stir evenly to obtain the first mixed solution; add propargyl phenolic aldehyde (PN)...

Embodiment 1

[0029] This embodiment provides a method for preparing polycarbosilane with high molecular weight and high linearity, comprising the following steps:

[0030] S1: Put polydimethylsilane (PDMS) in a distillation apparatus, carry out distillation under the protection of high-purity nitrogen, and collect fractions at 102°C; wherein, the flow rate of nitrogen is 60mL / min.

[0031] S2: Put the distillate in a three-necked flask equipped with a cracking column, a condenser and a receiving device, feed nitrogen, raise the temperature to 420°C at a rate of 2°C / min and keep it warm for 24 hours, cool it down to room temperature naturally, and take it out to obtain a silane oligomer . Wherein, the nitrogen flow rate is 200mL / min.

[0032] S3: Dissolve the silane oligomer in xylene, place in a fume hood and stir evenly to obtain the first mixed solution; add propargyl phenolic aldehyde (PN) and divinylbenzene (DVB) to the first mixed solution, heat Keep warm at 80°C and stir until most...

Embodiment 2

[0036] This embodiment provides a method for preparing polycarbosilane with high molecular weight and high linearity, comprising the following steps:

[0037] S1: Put polydimethylsilane (PDMS) in a distillation apparatus, carry out distillation under the protection of high-purity argon, and collect fractions at 105°C; wherein, the flow rate of argon is 80mL / min.

[0038] S2: Put the distillate in a three-neck flask equipped with a cracking column, a condenser and a receiving device, pass in argon gas, raise the temperature to 420°C at a rate of 2°C / min and keep it warm for 28h, cool it down to room temperature naturally, and take it out to obtain silane oligomerization things. Wherein, the inert gas is nitrogen or argon, and the gas flow rate is 150 mL / min.

[0039] S3: Dissolve the silane oligomer in xylene, place in a fume hood and stir evenly to obtain the first mixed solution; add propargyl phenolic aldehyde (PN) and divinylbenzene (DVB) to the first mixed solution, heat ...

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Abstract

The invention relates to high-molecular-weight and high-linearity polycarbosilane and a preparation method and application thereof. The preparation method comprises the steps: S1, polydimethylsilane (PDMS) is distillated, and a fraction at 102-105 DEG C is collected; S2, the fraction is cracked to obtain a silane low polymer; S3, the silane low polymer is dissolved in xylene and stirred evenly, then propargyl novolac (PN) and divinyl benzene (DVB) are added, heating and stirring are conducted, and a mixed solution is obtained; and S4, the mixed solution is cracked, and then purified, and a final product is obtained. By adopting the technical scheme, the PDMS serves as a main raw material, a low-temperature decomposed product of the PDMS, namely the silane low polymer is mixed with the DVBand the PN, carbon-carbon dual bonds and silicon hydrogen bonds are heated to generate hydrosilylation, and a linear benzene-containing low polymer is formed; then heating condensation polymerizationis conducted to form the high-molecular-weight and high-linearity polycarbosilane; and the product is large in molecular weight, high in softening point, small in branching degree, and good in textileproperty, and is an ideal precursor for preparing SiC fibers.

Description

technical field [0001] The invention relates to the technical field of preparing silicon carbide ceramics, in particular to a polycarbosilane with high molecular weight and high linearity, a preparation method and application thereof. Background technique [0002] Based on its ultra-high strength and modulus, as well as good high temperature resistance and ablation resistance, silicon carbide (SiC) fibers have shown great application prospects in high-tech fields such as aerospace, rocket missiles and weaponry. At the same time, the preparation of silicon carbide fibers has always been a key topic of concern to scholars at home and abroad. Among them, the preparation of precursors is one of the most widely used and most mature methods. Precursor conversion method is an important method for preparing silicon carbide fibers, and the performance of precursors has a crucial influence on the performance of silicon carbide fibers. [0003] In recent years, polycarbosilane (PCS) i...

Claims

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Application Information

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IPC IPC(8): C08G77/60D01F9/10
Inventor 吴宝林侯振华
Owner 江西信达航科新材料科技有限公司
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