The crystallization kinetics of polyamide 66 in non-isothermal and isothermal conditions: Effect of nucleating agent and pressure
The crystallization kinetics of polyamide 66 in non-isothermal and isothermal conditions: Effect of nucleating agent and pressure
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聚酰胺 66 在非等温和等温条件下的结晶动力学：成核剂和压力的影响
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
D. Chomier
中科院分区：
文献类型：
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作者：
J. Won;R. Fulchiron;A. Douillard;B. Chabert;J. Varlet;D. Chomier
用DSC和高压差示扫描量热法研究了聚酰胺66的结晶动力学。在非等温条件下，在大气压下，首先使用Ozawa方程分析结果，得到原始等级的Avrami指数为4，成核聚酰胺的Avrami指数为2.1。然而，实验和计算的动力学显示结晶的结束部分的差异，可能是由于一个大的二次结晶现象。因此，将相对堆积归一化以从整个信号中提取初级结晶，并使用Douillard/Kim方程进行分析。在等温条件下，在大气压下，Avrami指数是类似的非等温条件下获得的值为处女和核级。此外，在结晶过冷度方面，在压力下的结晶进行了检查。在非等温条件下，结晶过冷度（ΔTc）随冷却速率的增加而增加，但由于结晶温度的增加是由于平衡熔融温度的增加，因此不受压力的影响。在等温条件下，对于相同的结晶温度，过冷度（AT）随着压力的增加而增加。
The crystallization kinetics of virgin and nucleated polyamide 66 was investigated in non-isothermal and isothermal conditions, by use of DSC and high pressure dilatometry. In non-isothermal conditions, at atmospheric pressure, the results were first analyzed using the Ozawa equation, leading to an Avrami exponent of 4 in the case of the virgin grade and 2.1 for the nucleated polyamide. However, experimental and calculated kinetics showed a difference in the ending part of the crystallization, likely due to a large secondary crystallization phenomenon. Thus, the relative crystallinities were normalized to extract the primary crystallization from the whole signal and analyzed using the Douillard/Kim equation. In isothermal conditions, at atmospheric pressure, the Avrami exponents were similar to the values obtained in non-isothermal conditions for both virgin and nucleated grades. Furthermore, the crystallization under pressure was examined in terms of crystallization supercooling. In non-isothermal conditions, the crystallization supercooling (ΔTc) increases when the cooling rate increases, but it is not affected by the pressure since the crystallization temperature increase is due to the equilibrium melting temperature rise. In isothermal conditions, the supercooling (AT) rises according to the increase of the pressure for the same crystallization temperature.