Polyamides are important commercial polymer materials used in a variety of applications for their physicochemical and mechanical characteristics. The polyamide 1 (PA1) without methylene in molecular chain is supposed to own the highest density of hydrogen bond, dipole and –HNCO– group in the molecular chain. Therefore, it is supposed to be an ideal multifunctional and high-performance material. While low productivity in solid state polycondensation and high melt viscosity in melt polycondensation are still big challenges for preparing polyamides. In this work, the PA1 was successfully synthesized in supercritical carbon dioxide and urea was used as raw material. The synthetic technology of PA1 was referred to the urea polycondensation reaction, and made full use of the advantages of supercritical carbon dioxide: low viscosity and high diffusion coefficient. In this method, the CO<sub>2</sub> not only played a role of reaction mediator, but also the absorbent of small molecular byproduct (NH<sub>3</sub>). According to DSC analysis, the glass transition temperature of the PA1 was 135.4 °C. Wide angle X-ray diffraction showed that a sharp and intense diffraction peak occurred at 27.68°, indicating its highly crystalline nature. Thermogravimetric analysis indicated that the PA1 was thermal stable below 340 °C. The temperatures of 2% and 5% weight loss were 340.4 and 378.0 °C. In addition, the crystallization behaviors effect on PA11 after adding PA1 were investigated through isothermal crystallization and nonisothermal crystallization analysis by DSC. Both the crystalline degree and crystallization rate of polyamide 11 increased with the addition of PA1.

Synthesis of polyamide 1 in supercritical carbon dioxide & its crystallization behavior effect on polyamide 11

256th National Meeting (2018)

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