A kind of radiation cross-linked polymethacrylimide foam and preparation method thereof

Abstract

The invention discloses a radiation cross-linked polymethacrylimide foam and a preparation method thereof, comprising the following steps: (1) mixing the raw materials uniformly, then injecting them into a closed flat mold and carrying out polymerization at 30-60° C. reaction; (2) react until the reaction solution solidifies and becomes a uniform transparent state, then heat up to 60-130 ° C and carry out post-polymerization treatment for 20-60 h to obtain a poly(meth)acrylimide prepolymerized plate; (3) ) heating and foaming the poly(meth)acrylimide prepolymerized plate at 180-260° C. to obtain the poly(meth)acrylimide foam; (4) foaming the poly(meth)acrylimide The amine foam is treated with double-sided irradiation under an electron accelerator to obtain a cross-linked poly(meth)acrylimide foam. Compared with the conventional foam, the mechanical properties and heat resistance of the poly(meth)acrylimide foam prepared by the invention are obviously improved.

Description

technical field [0001] The invention relates to the field of material preparation, in particular to a radiation-crosslinked polymethacrylimide foam and a preparation method thereof. Background technique [0002] Poly(meth)acrylimide (PMI) foam is prepared by free radical copolymerization of (meth)acrylic acid, (meth)acrylonitrile and comonomers, and its molecular side chain contains a large number of carboxyl and nitrile groups. Such strong polar groups make the PMI foam have extremely high specific strength, and the carboxyl and nitrile groups undergo imidization reaction at high temperature, which improves the heat resistance of the material. PMI foam has the advantages of high specific strength, high heat resistance, and corrosion resistance, and is widely used in aerospace, wind power generation, new energy vehicles, sports equipment, high-speed rail ships, and medical equipment. The polymerization principle and reaction process of PMI foam are shown in the following fo...

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Problems solved by technology

However, the heat deflection temperature of the PMI foam material obtained by this method does not increase much, only about 200°C, which still cannot meet the curing process of carbon fiber / bismaleimide prepreg

[0007] In the patent CN201510472532.X, by adding calcium oxide or magnesium oxide nucleating agent to the system, small-pore polymethacrylimide foam with high heat distortion temperature was prepared. Meet the curing process of carbon fiber / bismaleimide prepreg

[0008] Patent CN201510472393.0 increases the heat-resistant temperature of PMI foam to about 220°C by adding heat-resistant additives such as tribromophenylmaleimide, dimethyl methylphosphonate DMMP or inorganic oxides to the system, and it cannot Meet the curing process of carbon fiber / bismaleimide prepreg

[0009] Photoinitiators, also known as photosensitizers, are very important in photocuring systems. In actual formulations, most of them are small molecule photoinitiators with small molecular weight and high mobility. layer turns yellow, reducing photoinitiation efficiency

[0010] To sum up, to meet the curing process of carbon fiber / bismaleimide prepreg, it is necessary to increase the heat-resistant temperature of PMI foam to about 250°C, while conventional PMI foam cannot reach such a high heat distortion temperature. To further increase the heat distortion temperature, it is necessary to increase the crosslinking density of the system. However, if the crosslinking density of the PMI plastic board is increased, then the PMI plastic board is prone to cracking during the foaming process, which has led to most of the current PMI foam low heat distortion temperature

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