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利用DSC方法研究了不同热历史条件对尼龙1212熔融行为的影响.不同的热历史条件下,在DSC曲线上,观察到尼龙1212产生2个或3个熔融峰,依据聚合物结晶理论,对各峰的来源进行了分析.在160℃下不同温度退火120 min的尼龙1212样品DSC曲线上,低温结晶熔融峰主要由低温结晶形成的一些微晶体或者片晶熔融产生,其晶体完善程度较差,熔融峰值较低,峰面积较小;主熔融峰是由样品在淬火过程中形成的晶体和升温过程中低温结晶形成的晶体的熔融重结晶形成较为完善的晶体熔融所产生,熔融峰值较高,峰面积较大.在不同的升温速率条件下,熔融峰温度有所移动,表明不同升温速率条件下产生的熔融峰的结晶晶型是相同的.在不同结晶时间下结晶,延长结晶时间对较高完善程度晶体的生长有利.在不同温度下依次退火处理的样品,熔融产生两个附加峰,这两个附加峰的峰温都比它们相应的退火温度高,而峰高和峰面积随退火温度降低而减小.根据等温结晶结果,由Hoffman方法确定了尼龙1212的平衡熔融温度为202.8℃.
The influence of different thermal history conditions on the melt behavior of nylon 1212 was studied by DSC method. Under different thermal history conditions, two or three melting peaks of nylon 1212 were observed on the DSC curve. According to the theory of polymer crystallization, The source of the peak was analyzed.At the DSC curve of nylon 1212 sample annealed at different temperatures for 120 min at 160 ℃, the low-temperature crystal melting peak was mainly produced by the melting of some microcrystals or platelets formed by low temperature crystallization, the crystal refinement was poor , The melting peak is lower and the peak area is smaller. The main melting peak is formed by the melt recrystallization of the crystal formed during the quenching of the sample and the crystal formed by the low-temperature crystallization in the temperature rising process, resulting in a relatively high melting peak , The peak area is larger.Under the different heating rate conditions, the melting peak temperature is shifted, indicating that the crystallization temperature of the melting peak under the different heating rate conditions are the same.Crystallization at different crystallization time, to extend the crystallization time Crystals of the higher perfect crystal grow favorably. Samples annealed at different temperatures in turn produce two additional peaks melting, the peak temperatures of these two additional peaks are higher than those of them Annealing temperature should be high, and the peak height and peak area decreases as the annealing temperature is decreased. According to the results of isothermal crystallization, determined by the method of Hoffman equilibrium melting temperature of the nylon 1212 was 202.8 deg.] C.