The method of additive properties was used to calculate the dynamic mechanical relaxation time for a series of polyurethanes. Calculations were also made of density and glass transition temperature. Group contributions for nine component groups were determined. With these group values, the densities of the 12 polymers used to determine the groups were calculated and found to agree with measured values within an average of 0.2%. Calculated glass transition temperatures also agreed with measured values within 0.2%. The relaxation time, defined as a parameter in the Havriliak-Negami equation, was shown to be correlated with the glass transition temperature, allowing relaxation time to also be expressed as an additive property. Calculated logarithms of relaxation times agree with measured values to within 7% over a range of relaxation times covering many decades. (C) 1996 John Wiley & Sons, Inc. [References: 13]
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机译：添加剂性能的方法用于计算一系列聚氨酯的动态机械弛豫时间。还对密度和玻璃化转变温度进行了计算。确定了九个组成部分的小组贡献。利用这些基团值，计算出用于确定基团的12种聚合物的密度，发现与实测值一致，平均值在0.2％以内。计算的玻璃化转变温度也与0.2％以内的测量值一致。松弛时间定义为Havriliak-Negami方程中的参数，已显示与玻璃化转变温度相关，因此松弛时间也可以表示为加性。在涵盖数十年的一系列弛豫时间范围内，弛豫时间的计算对数与测量值一致，在7％之内。 （C）1996 John Wiley＆Sons，Inc. [参考：13]
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