ポリエチレンの溶融粘弾性

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書誌事項

タイトル別名
  • Viscoelastic Properties of High-Density Polyethylene Melts
  • ポリエチレン ノ ヨウユウネンダンセイ

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説明

The dynamic viscosity η' and rigidity G' have been measured by means of the rotational cylinder type rheometer described elsewhere for seven types (A to G) of high-density polyethylene manufactured by three different processes. The measurements have been carried out in a frequency range from 0.001 to 0.5cps at five temperatures ranging from 180 to 260°C.<br>These materials do not necessarily have the same frequency dependence of η' and G', and can be classified into four groups. Polymers D and E have the same frequency dependence of η' and G' in the frequency range covered by the experiment and η' vs. ω or G' vs. ω curve (ω denotes angular frequency) can be superposed into a composite curve by shifting them along a straight line having the slope of -1 or the abscissa. This also holds for polymers F and G, but the η' and G' curves for these polymers intersect with those for polymers D and E. The polymers A and B have the same frequency dependences of η' and G' on each other but are different from the above materials.<br>The polymer C is quite different from others. The frequency dependence of η' for this polymer is much larger and that of G' is much smaller than the other materials.<br>In some cases, the difference in the frequency dependence of η' and G' for different materials may be ascribed to the presence and the nature of double bonds included in the polymer chains as verified from the infrared spectrum. In other cases, the difference may be due to the difference in the molecular weight distribution as elucidated by the fractionation with the column method and turbidity titration.<br>The frequency dependence of η' for the polymer having bimodal distribution is greater than for the polymer having normal distribution, and that of G' is reverse. The absolute values of η' and G' for the polymer having bimodal distribution tend to be higher than the normal for a given weight-average molecular weight. Moreover, the polymer having bimodal distribution have larger shift factor and lower fluidity than the normal, indicating that the molecular weight distribution is very important to the flow properties of polymer melts.

収録刊行物

  • 材料

    材料 14 (139), 304-307, 1965

    公益社団法人 日本材料学会

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