High molecular weight polycarbosilane and preparation method thereof

A technology of polycarbosilane and high molecular weight, which is applied in the field of high molecular weight polycarbosilane and its preparation, can solve the problems of low content of reactive groups, high content of free carbon, high oxygen content of SiC fibers, etc., and achieve high free radical concentration, The product has a large molecular weight and is easy to synthesize in batches

Active Publication Date: 2018-06-29
南昌嘉捷天剑新材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] But domestic PCS still has a lot of deficiencies
Domestic PCS itself is rich in carbon, and the SiC fiber prepared from it has high free carbon content and poor high temperature stability; the content of reactive groups such as Si-H in PCS is low and the activity is low, and it needs to be infused in the air before the fiber is fired. , introducing a large amount of oxygen, the

Method used

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  • High molecular weight polycarbosilane and preparation method thereof
  • High molecular weight polycarbosilane and preparation method thereof
  • High molecular weight polycarbosilane and preparation method thereof

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment 1 proposes a kind of high molecular weight polycarbosilane, and the molecular structure of described polycarbosilane is:

[0027]

[0028] Among them, R 1 for H, R 2 for

[0029] m is a positive integer, n, p, q are positive integers <5.

[0030] The preparation method of the high molecular weight polycarbosilane of embodiment 1 comprises the steps:

[0031] Polydimethylsilane pretreatment: place polydimethylsilane in a distillation device, distill under a high-purity nitrogen atmosphere with a flow rate of 80 mL / min and collect fractions at 105°C.

[0032] Polydimethylsilane cracking reaction: the pretreated polydimethylsilane and reducing metal powder are successively placed in an autoclave, and the reducing metal powder is evenly distributed on the surface of the polydimethylsilane , and then replaced by nitrogen for 3 times, and pre-introduced 0.5MPa nitrogen with a flow rate of 120mL / min, then raised the temperature to 320°C at a heating rate of...

Embodiment 2

[0036] Embodiment 2 proposes a kind of high molecular weight polycarbosilane, and the molecular structure of described polycarbosilane is:

[0037]

[0038] Among them, R 1 for R 2 for

[0039] m is a positive integer, n, p, q are positive integers <5.

[0040] The preparation method of the high molecular weight polycarbosilane of embodiment 2 comprises the steps:

[0041] Polydimethylsilane pretreatment: place polydimethylsilane in a distillation device, distill under a high-purity nitrogen atmosphere with a flow rate of 120mL / min and collect fractions at 100°C.

[0042] Polydimethylsilane cracking reaction: the pretreated polydimethylsilane and reducing metal powder are successively placed in an autoclave, and the reducing metal powder is evenly distributed on the surface of the polydimethylsilane , and then pass nitrogen replacement 5 times, and pre-feed 2MPa nitrogen at a flow rate of 80mL / min, then raise the temperature to 360°C at a heating rate of 295°C / h and k...

Embodiment 3

[0046] Embodiment 3 proposes a kind of high molecular weight polycarbosilane, the molecular structure of described polycarbosilane is:

[0047]

[0048] Among them, R 2 for H, R 1 for

[0049] m is a positive integer, n, p, q are positive integers <5.

[0050] The preparation method of the high molecular weight polycarbosilane of embodiment 3 comprises the steps:

[0051] Polydimethylsilane pretreatment: place polydimethylsilane in a distillation device, distill under a high-purity nitrogen atmosphere with a flow rate of 100 mL / min and collect fractions at 103°C.

[0052] Polydimethylsilane cracking reaction: the pretreated polydimethylsilane and reducing metal powder are successively placed in an autoclave, and the reducing metal powder is evenly distributed on the surface of the polydimethylsilane , and then replaced by nitrogen for 4 times, and pre-filled with 1.2MPa nitrogen at a flow rate of 100mL / min, then raised the temperature to 340°C at a heating rate of 215...

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Abstract

The invention relates to high molecular weight polycarbosilane and a preparation method thereof. The method comprises the following steps: distilling polydimethylsilane, mixing the distilled polydimethylsilane with reducing metal powder, then heating up to 320-360 DEG C and carrying out heat preservation for 3.8-4.2h, and then cooling to room temperature to obtain a liquid split product-polysilane; adding divinyl benzene and polymetylhydrosiloxane, heating up to 320-360 DEG C, and carrying out heat preservation for 1.8-2.2h; then, heating up to 420-460 DEG C, carrying out heat preservation for5-7h, and then cooling to room temperature to obtain a polycarbosilane crude product; dissolving the crude product in xylene, filtering, and then introducing nitrogen; after that, heating up to 420-460 DEG C, carrying out heat preservation for 1.8-2.2h, and then cooling to 320-360 DEG C to obtain the high molecular weight polycarbosilane. The preparation method provided by the invention is simplein technology, low in requirements for equipment and easy in implementation of batch synthesis; the product is high in molecular weight and purity, and the synthetic yield reaches 70 or above.

Description

technical field [0001] The invention belongs to the technical field of silicon carbide ceramic materials, and in particular relates to a high molecular weight polycarbosilane and a preparation method thereof. Background technique [0002] In recent years, SiC ceramic fibers have shown good application prospects in aerospace, weaponry and other fields due to their ultra-high strength and modulus, excellent high temperature resistance, oxidation resistance, and corrosion resistance. Among them, the precursor conversion method is an effective method for preparing SiC ceramic fibers. The precursor conversion method is to use the excellent fluidity, formability, processability and structural designability of polymers to form ceramic materials. Polycarbosilane (PCS) is the earliest precursor used to prepare SiC fibers. In 1975, Yajima of Japan used polycarbosilane to prepare SiC fibers for the first time and used them in production, creating a new method for preparing inorganic ...

Claims

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Application Information

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IPC IPC(8): C08G77/60
CPCC08G77/60
Inventor 吴宝林侯振华
Owner 南昌嘉捷天剑新材料有限公司
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