Challenges in the experimental investigation of the caloric and thermomechanical behaviour of semi-crystalline polymers
Challenges in the experimental investigation of the caloric and thermomechanical behaviour of semi-crystalline polymers
复制标题
半结晶聚合物热量和热机械行为实验研究的挑战
DOI：
10.1016/j.polymertesting.2019.106252
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发表时间：
2020
期刊：
影响因子：
5.1
通讯作者：
Mittermeier
中科院分区：
文献类型：
--
作者：
Mittermeier
对工业生产的聚对苯二甲酸乙二醇酯(PET)在玻璃态到液态的温度范围内进行了研究。在差示扫描量热仪(DSC)实验中，样品以不同的速度多次穿过这个温度范围，中间被等温段打断。因此，在早期出版物中观察到的卡路里行为可以得到证实。仔细观察就会发现，根据样本的初始状态，行为会发生变化。热和力学边界条件似乎对半晶态有长期的影响。与初始状态无关，在每个温度循环后，结晶倾向都会发生根本性的下降。最有可能的解释是在更高的温度范围内分子量增加。这会导致粘度的增加，因为它发生在固体缩聚(SSP)过程中。力学实验也是在所研究的温度范围内进行的，但由于实验限制，只能在不同的等温水平下进行。对于这些实验，理论上的考虑是基于胡克定律的粘弹性推广。这说明在玻璃化转变范围内，剪切刚度与体积刚度之比的显著降低对材料性能的影响。当单轴拉伸模式失效时，抑制横向膨胀的单轴压缩模式需要类似流体的行为来确定体积弹性模量，而不是纵向弹性模量。实验研究证实了这些理论结果。关于力学研究的实际目的，在更高的等温水平上使用了Struik方案。因此，可以观察到与结晶有关的力学行为的变化。
Investigations on industrial produced polyethylene terephthalate (PET) were carried out in the temperature range from the glassy to the liquid state. In differential scanning calorimetry (DSC) experiments, the sample passed through this temperature range several times at different speeds, interrupted by isothermal segments. Thereby the caloric behaviour observed in earlier publications could be confirmed. A closer look reveals variations in the behaviour, depending on the initial state of the sample. The thermal and mechanical boundary conditions seem to have a long-term influence on the semi-crystalline state. Independent of the initial state, a fundamental decrease in the crystallization tendency could be observed after each temperature loop. The most likely explanation for that is an increase in molecular weight in the higher temperature ranges. This leads to an increase in viscosity, as it occurs in the solid poly-condensation (SSP) process. Mechanical experiments were also carried out in the temperature range investigated, but only at different isothermal levels due to experimental limits. For these experiments, theoretical considerations were made on the basis of the viscoelastic generalization of Hooke’s law. These show the influence of the significant decrease of the ratio between shear- and bulk stiffness in the glass-transition range. While the uniaxial tensile mode fail, the uniaxial compression mode with suppressed transversal expansion needs the fluid like behaviour to determine the bulk modulus instead of the longitudinal modulus. The experimental investigations confirm these theoretical results. Concerning the actual purpose of the mechanical investigation, Struik’s protocol is used at higher isothermal levels. As a result, crystallization-related changes in the mechanical behaviour could be observed.
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影响因子：
1.7
作者：
KONO, R
通讯作者：
KONO, R
聚对苯二甲酸乙二醇酯的固态聚合：动力学和性能参数
DOI：
--
发表时间：
1986
期刊：
影响因子：
--
作者：
S. Jabarin;E. A. Lofgren
通讯作者：
E. A. Lofgren
热结晶聚对苯二甲酸乙二醇酯的转变和熔化行为及其与 ftir 和密度测量的相关性
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
S. Lin;J. Koenig
通讯作者：
J. Koenig
聚对苯二甲酸乙二醇酯的动态机械性能
DOI：
--
发表时间：
1958
期刊：
影响因子：
--
作者：
T. Kawaguchi
通讯作者：
T. Kawaguchi
影响因子：
5.5
作者：
Di Lorenzo, Maria Laura;Righetti, Maria Cristina;Wunderlich, Bernhard
通讯作者：
Wunderlich, Bernhard