Influence of temperature and chain orientation on the crystallization of poly(ethylene terephthalate) during fast drawing
Influence of temperature and chain orientation on the crystallization of poly(ethylene terephthalate) during fast drawing
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DOI：
10.1016/s0032-3861(00)00129-4
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发表时间：
2000-10
期刊：
影响因子：
4.6
通讯作者：
A. Mahendrasingam;D. J. Blundell;C. Martin;W. Fuller;D. Mackerron;J. Harvie;R. Oldman;C. Riekel
中科院分区：
文献类型：
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作者：
A. Mahendrasingam;D. J. Blundell;C. Martin;W. Fuller;D. Mackerron;J. Harvie;R. Oldman;C. Riekel
通过对聚对苯二甲酸乙二酯在拉伸速率(0.0 5~12s−1)、温度(90~12 0°C)和拉伸倍数下机械变形过程中记录的时间分辨广角X射线散射数据的详细分析，确定了三种变形区域。结晶开始时的晶化速率与取向参数〈P2(cosθ)〉)的比较表明，晶化速率与温度和分子取向都有很强的依赖关系。以前观察到的结晶速率对温度的不敏感性是偶然选择拉伸条件的结果，在这种条件下，温度和分子取向的相反影响产生了相似的净结晶速率。用WLF位移因子分析了温度依赖性的影响，揭示了结晶速率对〈P2(cosθ)〉)的大约4次方的总体依赖关系。在较高的拉伸温度下，链回缩运动的速度快于拉伸速度，晶链轴线明显偏离拉伸方向。在结晶过程中，晶体的倾斜度和晶体反射的半宽度在整个结晶过程中基本保持不变。
Three regimes of poly(ethylene terephthalate) (PET) deformation are identified from a detailed analysis of time-resolved wide angle X-ray scattering (WAXS) data recorded during the mechanical deformation of PET at a wide range of draw rates (0.05–12s−1), temperatures (90–120°C) and draw ratios. These are: A comparison of the crystallization rate with the orientation parameter 〈P2( cos θ)〉 at the onset of crystallization shows a strong dependence of the crystallization rate on both temperature and molecular orientation. It is proposed that a previously observed insensitivity of crystallization rate to temperature was a consequence of fortuitous choice of drawing conditions in which the opposing effects of temperature and molecular orientation produced similar net crystallization rates. The effects of the temperature dependence have been factored out using a WLF shift factor to reveal an overall dependence of the crystallization rate on approximately the fourth power of 〈P2( cos θ)〉. At high draw temperatures where the rate of the chain retraction motion is faster than the draw rate, there is a significant tilt of the crystal chain axis away from the draw direction. During the crystallization process both the degree of crystal tilt and the half-width of the crystal reflections remain essentially unaltered over the whole crystallization process.