One-pot synthesis of long carbon-chain nylon 1012 and its properties
The preparation of nylon by traditional melt polycondensation usually first prepares nylon salt to improve the thermal stability of the monomer and ensure the molar ratio of the acid amine,and then carries out subsequent polymerization.The preparation of long carbon-chain nylon has a higher molecular weight of monomer and better thermal stability,so it has the possibili-ty of one-pot melt polycondensation by omitting the cumbersome salt formation process.Long carbon-chain nylon 1012(PA1012)was successfully prepared by one-pot method,and the effects of pre-polymerization,post-polymerization and final polymerization on the properties of the product were investigated.The optimal polymerization parameters for one-pot preparation of PA1012 were found to be as follows:pre-polymerization temperature,pre-polymerization time,post-polymerization temperature and post-polymerization time were 190℃,2.5 h,240℃ and 1 h,respectively,and the final polymerization time is selected according to the needs of the product.Subsequently,the kinetic parameters of polymerization of PA1012 in the pre-polymerization stage at 190℃ and in the post-polymerization stage at 240℃ were further explored,and the reaction rate constants were 16.66,90.01 g/(mol·min),respectively.The structure of the product was characterized using infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy,which showed that PA 1012 was successfully synthesized.The thermal properties of PA1012 were analyzed using thermal gravimetric analyzer and differential scanning calorimetry,which indicated that PA1012 had good heat resistance and thermal stability.The mechanical properties of PA1012 were tested,which revealed that PA1012 had excellent mechanical proper-ties.The above results demonstrate the feasibility and high efficiency of synthesizing the new long carbon-chain PA by one-pot method.
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