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Method for synthetizing polycarbosilane under atmospheric pressure

A technique for synthesizing polycarbosilane under normal pressure, which is applied in the field of synthesizing polycarbosilane under normal pressure, can solve the problems of not reaching the synthesis yield of high-pressure method, achieve the effects of easy batch synthesis, simple equipment, and lower reaction temperature

Inactive Publication Date: 2012-05-02
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

South Korea’s Young Hee Kim et al. added a small amount of zeolite-like silicate (Si / Al=30) compound to PDMS as a catalyst, and reacted at 400°C under normal pressure for a certain period of time to obtain PCS with a certain viscosity, and the yield can be increased to 50%; however, the actual yield was only 45% after the sticky material was removed
To sum up, at present, the yield of PCS synthesized by normal pressure method is far from reaching the level of synthesis yield (generally above 60%) by high pressure method

Method used

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  • Method for synthetizing polycarbosilane under atmospheric pressure
  • Method for synthetizing polycarbosilane under atmospheric pressure
  • Method for synthetizing polycarbosilane under atmospheric pressure

Examples

Experimental program
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Effect test

Embodiment 1

[0018] (1) Under the protection of high-purity nitrogen, the solid raw material PDMS is cracked and converted into LPS in a nitrogen atmosphere above 360 ​​°C; (2) 200g LPS is placed in an atmospheric pressure high-temperature cracking synthesis reactor, and 65g of raw materials are added to LPS PDMS, stirred evenly, sealed, and replaced the gas in the kettle with high-purity nitrogen three times; under the protection of high-purity nitrogen, the temperature was raised to 280 ° C for 6 h; (3) the temperature was programmed to 410 ° C for 10 h, and 172 g of the product PCS was obtained after cooling.

[0019] The product PCS has a softening point of 180-195°C and a ceramic yield of 61.9wt%. It can be dissolved in organic solvents such as tetrahydrofuran and xylene, and the synthesis yield is 64.9%.

[0020] figure 2 is the FTIR spectrum of the product PCS. Depend on figure 2 It can be known that, compared with the existing atmospheric pressure catalytic synthesis method, th...

Embodiment 2

[0023] (1) Same as step (1) of Example 1; (2) Put 200g LPS in the normal pressure high temperature pyrolysis synthesis reaction kettle, add 200g raw material PDMS to the LPS, stir evenly, seal, replace the gas in the kettle with high-purity nitrogen Three times, under the protection of high-purity nitrogen, the temperature was raised to 300 ° C for 3 h; (3) then the temperature was programmed to 420 ° C for 6 h, and after cooling, 241 g of the product PCS was obtained.

[0024] The product PCS has a softening point of 185-200°C and a ceramic yield of 63.7wt%. It can be dissolved in organic solvents such as tetrahydrofuran and xylene, and the synthesis yield is 60.3%.

Embodiment 3

[0026] (1) Same as step (1) of Example 1; (2) Put 200g LPS in the normal pressure high temperature pyrolysis synthesis reaction kettle, add 100g raw material PDMS to the LPS, stir evenly, seal, replace the gas in the kettle with high-purity nitrogen Three times, under the protection of high-purity nitrogen, the temperature was raised to 330°C for 2 hours; (3) Then the temperature was programmed to rise to 370°C for 12 hours, and 184 g of the product PCS was obtained after cooling.

[0027] The product PCS has a softening point of 170-180°C and a ceramic yield of 59.1wt%. It can be dissolved in organic solvents such as tetrahydrofuran and xylene, and the synthesis yield is 61.3%.

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Abstract

A method for synthetizing polycarbosilane under the atmospheric pressure comprises the following steps: under the protection of high purity nitrogen, cracking solid raw material-polydimethylsilane at above 360 DEG C in nitrogen atmosphere to convert to liquid polysilane; (2) adding solid powdery raw material-polydimethylsilane which accounts for 15-100wt% of liquid polysilane in liquid polysilane, stirring evenly, sealing, heating to 280-330 DEG C under the protection of high purity nitrogen, reacting for 2-6h; and (3) performing temperature programming to 370-420 DEG C, and reacting for 6-12h and cooling. The method has low reaction temperature, the synthetic yield is more than 60%; the structure of precursor polycarbosilane (PCS) can not be changed; the equipment is simple; and large-scale synthesis is easy to realize and synthetic steps are less.

Description

technical field [0001] The invention relates to a method for synthesizing polycarbosilane, in particular to a method for synthesizing polycarbosilane under normal pressure. Background technique [0002] With the development of high technologies such as aviation, aerospace, weapons, and energy, higher and higher requirements are put forward for high-temperature thermal structural materials. Traditional metal materials and polymer materials have been difficult to meet these application requirements. In recent years, with C f / SiC、SiC f Fiber-reinforced silicon carbide-based composite materials represented by / SiC have been widely used in aviation, aerospace, automobiles and other fields because they can maintain high strength and high modulus characteristics at high temperatures, and at the same time, their mass is much smaller than that of metals and alloy materials. . [0003] The preparation of fiber-reinforced silicon carbide matrix composites often adopts the precurso...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G77/60
Inventor 薛金根邹治春谢征芳王浩王军
Owner NAT UNIV OF DEFENSE TECH
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