Synthesis method for increasing polycarbosilane (PCS) yield

A technology of polycarbosilane yield and polycarbosilane, which is applied in the synthesis field of improving polycarbosilane yield, can solve problems such as low PCS synthesis yield, waste of manpower and material resources, and waste of materials, so as to improve process improvement efficiency and avoid Emissions, the effect of improving the synthesis yield

Inactive Publication Date: 2018-10-19
NAT UNIV OF DEFENSE TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, the annual production of PCS produced by the normal pressure method in China has reached the level of hundreds of tons, and the low synthesis yield of PCS has caused a lot of waste of manpower and material resources.
At the same time, the atmospheric pressure method is accompanied by a large amount of liquid by-products in the production process. With the current PCS production capacity expanding, the liquid by-products will accumulate more and more, causing environmental pollution and waste of materials.

Method used

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  • Synthesis method for increasing polycarbosilane (PCS) yield
  • Synthesis method for increasing polycarbosilane (PCS) yield
  • Synthesis method for increasing polycarbosilane (PCS) yield

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] (1) Put 360g of PDMS in a three-necked flask, raise the temperature to 420°C for 8 hours under the protection of nitrogen, and carry out pyrolysis rearrangement reaction to prepare P-PCS;

[0038] (2) Dissolve the P-PCS obtained in step (1) with 200ml of xylene, filter and distill, distill at 350°C for 1 hour to remove the xylene, and distill at 350°C for 1 hour to obtain the product PCS and the distilled LPCS, PCS The yield is 31%;

[0039] (3) LPCS is recovered and mixed with 360g PDMS, and steps (1) and (2) are repeated;

[0040] (4) When the above steps were repeated until the 8th time, the amount of LPCS added was 145g, and the recovered LPCS was 145g equally, and the yield of PCS was 40% at this moment.

[0041] The process of using PDMS as raw material to synthesize PCS for the first time can be regarded as the traditional method for synthesizing PCS. In contrast, the yield of PCS is increased from 31% to 40%.

Embodiment 2

[0043] (1) Put 360g of PDMS in a three-necked flask, raise the temperature to 450°C for 8 hours under the protection of nitrogen, and carry out pyrolysis rearrangement reaction to prepare P-PCS;

[0044] (2) Dissolve the P-PCS obtained in step (1) with 200ml of xylene, filter and distill, distill at 350°C for 1 hour to remove the xylene, and distill at 350°C for 1 hour to obtain the product PCS and the distilled LPCS, PCS The yield is 50%, the PCS at this time is named as PCS-1, and the LPCS is named as LPCS-1;

[0045] (3) LPCS is recovered and mixed with 360g PDMS, and steps (1) and (2) are repeated;

[0046] (4) When the process of preparing PCS was repeated to the 6th time, the amount of LPCS added was 94g, and the gained LPCS was 94g equally. At this time, the yield of PCS was 63%. The PCS at this time was named PCS-6, LPCS Named LPCS-6.

[0047] see figure 1 , wherein the process of preparing PCS with PDMS as a raw material for the first synthesis of PCS can be regard...

Embodiment 3

[0054] (1) Put 360g of PDMS in a three-necked flask, raise the temperature to 480°C for 8 hours under the protection of nitrogen, and carry out pyrolysis rearrangement reaction to prepare P-PCS;

[0055] (2) Dissolve the P-PCS obtained in step (1) with 200ml of xylene, filter and distill, distill at 350°C for 1 hour to remove the xylene, and distill at 350°C for 1 hour to obtain the product PCS and the distilled LPCS, PCS The yield is 57%;

[0056] (3) LPCS is recovered and mixed with 360g PDMS, and steps (1) and (2) are repeated;

[0057] (4) When the process of preparing PCS was repeated for the fourth time, the amount of LPCS added was 50 g, and the recovered LPCS was also 50 g, and the yield of PCS was 65%.

[0058] The process of using PDMS as raw material to synthesize PCS for the first time can be regarded as the traditional method for synthesizing PCS. In contrast, the yield of PCS is increased from 57% to 65%.

[0059] The yield of PCS can be stabilized at 63% with ...

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Abstract

The invention provides a synthesis method for increasing polycarbosilane (PCS) yield. The method comprises the following steps of using a mixture of polydimethylsilane (PDMS) and liquid polycarbosilane (LPCS) as raw materials, preparing a polycarbosilane pre-product (P-PCS) by pyrolysis rearrangement reaction; sequentially performing dissolving, filtering, atmospheric distillation for solvent removal and vacuum distillation on the P-PCS to obtain PCS and LPCS. According to the method, by recycling the by-product LPCS, the synthesis yield of PCS is increased; meanwhile, the obtained product still contains required PCS, no matter how many times the reaction is carried out, thereby ensuring the normal operation of the reaction and the required PCS yield.

Description

technical field [0001] The invention relates to the technical field of ceramic materials, in particular to a synthesis method for increasing the yield of polycarbosilane. Background technique [0002] Silicon carbide (SiC) fibers and silicon carbide matrix composites have excellent properties such as oxidation resistance, corrosion resistance and high specific strength / modulus, and are widely used in aviation, aerospace, atomic energy and other fields. Polycarbosilane is an important raw material for the preparation of SiC fibers and their composites. Polydimethylsilane (Polydimethylsilane, PDMS) high temperature pyrolysis rearrangement conversion method is currently the only method to achieve industrial production of PCS. The high-temperature pyrolysis rearrangement conversion method can be divided into high-pressure method and normal-pressure method according to the different synthesis pressure conditions. In foreign countries, the high-pressure method is often used for ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G77/60
CPCC08G77/60
Inventor 宋永才王国栋王军简科
Owner NAT UNIV OF DEFENSE TECH
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