The enthalpy of fusion and degree of crystallinity of polymers as measured by DSC
The enthalpy of fusion and degree of crystallinity of polymers as measured by DSC
复制标题
DOI：
10.1016/s0014-3057(03)00054-5
复制
发表时间：
2003-08-01
影响因子：
6
通讯作者：
Hay, JN
中科院分区：
文献类型：
--
作者：
Kong, Y;Hay, JN
结晶聚合物不处于热平衡，并且在平衡条件下还没有测量热力学参数，例如通过差示扫描量热法从宽温度范围内的熔融吸热下的区域测定的熔化焓。因此，基于熔化焓的结晶度的测量反映了实验条件，是不正确的，因为它们通常与通过其他分析方法（例如密度和WAX散射）确定的那些不一致，特别是当在环境温度下测量时。虽然这已被反复指出的程序，用于确定的熔融焓的基础上的聚合物的结晶度继续被广泛使用。使用第一定律的方法，熔融焓和结晶度已被测量作为温度的函数的金属茂聚乙烯和聚对苯二甲酸乙二醇酯在加热过程中。在加热之前对样品测量的结晶度与通过密度和广角X射线衍射测定的结晶度良好一致。(C)2003爱思唯尔有限公司。保留所有权利。
Crystalline polymers are not in thermal equilibrium and thermodynamic parameters such as enthalpy of fusion as determined by differential scanning calorimetry from the area under the melting endotherm over a wide temperature range have not been measured under equilibrium conditions. Accordingly measurements of the degree of crystallinity based on the enthalpy of fusion reflect experimental conditions, are incorrect in that they do not usually agree with those determined by other analytical procedures, such as density and WAX scattering, particularly when measured at ambient temperatures. While this has been repeatedly pointed out procedures used to determine the fractional crystallinity of polymers based on the enthalpy of fusion continue to be widely used.Using the First Law method, the enthalpy of fusion and fractional crystallinity have been measured as a function of temperature for metallocene polyethylene and polyethylene terephthalate during heating. The crystallinity measured on the sample prior to heating is in good agreement with that determined by density and wide angle X-ray diffraction. (C) 2003 Elsevier Ltd. All rights reserved.