Comparative techniques for molecular weight evaluation of poly (ethylene terephthalate) (PET)
Comparative techniques for molecular weight evaluation of poly (ethylene terephthalate) (PET)
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DOI：
10.1016/j.polymertesting.2005.05.006
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发表时间：
2005-09
期刊：
影响因子：
5.1
通讯作者：
N. B. Sanches;M. Dias;E. B. Pacheco
中科院分区：
文献类型：
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作者：
N. B. Sanches;M. Dias;E. B. Pacheco
采用溶液特性粘数法、熔体流动指数法（MFI）和尺寸排阻色谱法（SEC）对不同来源的聚对苯二甲酸乙二醇酯（PET）进行了分子量测定。使用了五个PET样品：用于瓶子生产的商业原生PET（BPET）;取自缩聚反应第一阶段的原生PET，类似于纤维级PET（FPET）;来自消费后软饮料瓶的PET薄片（RPET）;含有30wt%玻璃纤维的RPET复合材料（RPETComp）和RYNITE®，一种含有30wt%玻璃纤维的商业PET复合材料。溶液特性粘度通过三种方法测定：Billmeyer方程（ASTM D 4603）、连续稀释（ASTM D 2857）和Schulz-Blaschke方程。借助于具有内部校准曲线的熔体流动指数设备获得来自MFI的特性粘度，所述内部校准曲线允许熔体流动指数（MFI）和特性粘度之间的直接关联。在六氟异丙醇（HFIP）中用PMMA标准物进行尺寸排阻色谱（SEC），其允许测定PET样品的Mn <$、Mw <$和多分散性。还通过Mark-Houwink方程计算分子量，其中K和a的值取自文献。通过不同方法获得的分子量和特性粘数值之间的相关性，试图根据已知的特性粘数估计未知PET样品的分子量。
The molecular weight evaluation of poly(ethylene terephthalate) (PET) from different sources was accomplished by using three different techniques: solution intrinsic viscosity, intrinsic viscosity from melt flow index (MFI) and size exclusion chromatography (SEC). Five PET samples were used: commercial virgin PET, designed for bottle production (BPET); virgin PET taken from the first stage of condensation polymerization, similar to fiber grade PET (FPET); PET flakes from post-consumer soft drink bottles (RPET); RPET composite containing 30wt% of fiberglass (RPETComp) and RYNITE®, a commercial PET composite containing 30wt% of fiberglass. Solution intrinsic viscosity was determined by three methods: Billmeyer's equation (ASTM D 4603), successive dilutions (ASTM D 2857) and Schulz-Blaschke's equation. Intrinsic viscosity from MFI was obtained with the aid of melt flow index equipment provided with an internal calibration curve which allows the direct correlation between melt flow index (MFI) and intrinsic viscosity. Size exclusion chromatography (SEC) was carried out in hexafluoroisopropanol (HFIP) with PMMA standards, which allowed the determination of Mn¯, Mw¯ and polydispersity of the PET samples. Molecular weights were also calculated by Mark–Houwink's equation, with values of K and a taken from the literature. Correlation between molecular weight and intrinsic viscosity values obtained by different methods was done as an attempt to estimate the molecular weight of an unknown PET sample from its known intrinsic viscosity.