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首页> 外文期刊>Journal of Polymer Science, Part A. Polymer Chemistry >Synthesis and Physical Characterization of Model Hard Segments Based on Diphenyl Methane Diisocyanate and Hydroquinone Bis(2-hydroxyethyl) Ether
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Synthesis and Physical Characterization of Model Hard Segments Based on Diphenyl Methane Diisocyanate and Hydroquinone Bis(2-hydroxyethyl) Ether

机译：基于二苯基甲烷二异氰酸酯和对苯二酚双（2-羟乙基）醚的模型硬链段的合成和物理表征

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Hard segment model compounds based on diphenyl methane diisocyanate (MDI) and hydroquinone bis(2-hydroxyethyl) ether (HQE) were synthesized; these models were end-capped with ethanol (E) or 2-phenoxyethanol (F). NMR spectroscopy and GPC analysis confirm the expected structure: R-(MDI-HQE)_(p-1)-MDI-R'(where p=1,2,3;R,R'=E, and/or F if p=1). Intrinsic viscosity revealed a Mark-Houwink exponent of 0.73, and a value of 4.76X10~(-2) cc/g was obtained for K; applying the Mark-Houwink equation on a MDI-HQE polymer a MW of 2650 was calculated, while a value of 2872 was achieved by GPC analysis using a specifically drawn calibration curve. Thermal analysis reveals the crystalline nature of these models and the increase of melting temperature with the number of repeating units; an extrapolated value ranging from 274 to 361degC, depending on selected structure for the first term of the oligourethane series, was calculated for the polymer using the Flory's equation accounting for chain end defects. Calorimetric traces and GPC analyses on annealed samples show an extensive degradation of models having higher melting temperature (p>1), in this case a broad with molecular weight mixture, which contains also significant amounts of short oligourethanes or byproducts, was generally observed. A comparison of the melting behavior of this series with similar models based on MDI but with a different chain extender (1,4-butanediol, BDO) seems to indicate an increase in the melting temperature. This evidence can be tentatively attributed to the longer aromatic sequences present in the hydroquinone containing models. The investigation of the characteristics of these hard models gives predictive information useful for better understanding properties/structure relationships of polyurethane elastomers containing similar hard sequences.
机译：合成了基于二苯基甲烷二异氰酸酯（MDI）和对苯二酚双（2-羟乙基）醚（HQE）的硬链段模型化合物;这些模型使用乙醇（E）或2-苯氧基乙醇（F）封端。 NMR光谱和GPC分析证实了预期的结构：R-（MDI-HQE）_（p-1）-MDI-R'（其中p = 1,2,3; R，R'= E和/或F p = 1）。特性粘度显示出马克-霍温克指数为0.73，K值为4.76X10〜（-2）cc / g。在MDI-HQE聚合物上应用Mark-Houwink方程，计算得出的分子量为2650，而使用专门绘制的校准曲线通过GPC分析获得的值为2872。热分析揭示了这些模型的晶体性质以及随着重复单元数目的增加熔融温度的增加。使用考虑了链端缺陷的弗洛里方程，为聚合物计算了一个介于274至361℃的外推值，具体取决于低聚乙烷系列第一项的所选结构。退火样品的量热痕迹和GPC分析显示，具有较高熔融温度（p> 1）的模型发生了广泛的降解，在这种情况下，通常观察到分子量较大的混合物，其中还包含大量的短链低聚乙烷或副产物。与基于MDI的类似模型但具有不同的扩链剂（1,4-丁二醇，BDO）的该系列的熔融行为相比，似乎表明熔融温度有所提高。该证据可以暂时归因于存在于包含氢醌的模型中的更长的芳香族序列。对这些硬模型特性的研究提供了有助于更好地理解含有相似硬序列的聚氨酯弹性体的性能/结构关系的预测信息。

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