The temperature dependence of the viscoelastic softening and terminal dispersions of linear amorphous polymers
The temperature dependence of the viscoelastic softening and terminal dispersions of linear amorphous polymers
复制标题
线性无定形聚合物粘弹性软化和末端分散的温度依赖性
DOI：
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发表时间：
1982
期刊：
影响因子：
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通讯作者：
D. Plazek
中科院分区：
文献类型：
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作者：
D. Plazek
热流变简单性被示出为在从Tg + 25°C延伸至Tg + 80°C的温度范围内保持聚（乙酸乙烯酯）。在Tg和Tg + 25°C之间，软化（玻璃到橡胶状）粘弹性分散体表现出不同于终端（橡胶状到稳态）分散体的时间尺度移位因子aT。由零剪切粘度计算的aT值与在60-154°C的温度范围内（Tg ≥ 35°C）的末端分散体的aT值一致。在整个温度范围（42-154°C）内，从终端色散的响应中获得的aT位移可以拟合到威廉姆斯、Landel和Ferry方程。从软化分散体获得的aT显示出表现出不同的官能度。经验修正的杜利特尔方程产生了一个非常灵活的关系，可以拟合到一些aTs，不能由通常的杜利特尔自由体积表达式表示。
Thermorheological simplicity is shown to hold for poly(vinyl acetate) in the temperature range extending from Tg + 25°C to Tg + 80°C. Between Tg and Tg + 25°C the softening (glass to rubberlike) viscoelastic dispersion exhibits time-scale shift factors aT different from those of the terminal (rubberlike to steady-state) dispersion. The aT values calculated from zero-shear viscosities coincide with those from the terminal dispersion in the temperature range 60–154°C (Tg ≅ 35°C). The aT shifts obtained from the response in the terminal dispersion can be fitted to the Williams, Landel, and Ferry equation over the entire temperature range 42–154°C. The aT obtained from the softening dispersion is shown to exhibit a different functionality. An empirical modification of the Doolittle equation yields a very flexible relation which can be fitted to some aTs which cannot be represented by the usual Doolittle free-volume expression.