ポリエチレンテレフタレートの結晶化と誘電スペクトル : 結晶性高分子の構造とレオロジー
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For polyethylene terephthalate, relationships between the dielectric properties and the dynamic mechanical properties have been studied. And effects of crystallinity and crystallization temperature on anomalous dispersions (absorptions) in the dielectric properties have been surveyed. Dielectric measurements have been carried out over the frequency range of 0.1 to 10^6 c/s and temperature range of -35 to 110℃. Amorphous polythylene terephthalate have been crystallized at 118℃ (series 1) or 202℃ (series 2) and 10 samples having different degree of crystallinity have been prepared. If partially crystallized samples of series 1 and 2 are compared at the same degree of crystallinity, as judged by density, the spherulites in the sample of series 2 are large in size but smaller in number. The dynamic mechanical data have been adopted from Thompson and Woods' paper. For all samples, two dielectric disperions (absorptions) are observed. A main absorption (α) locates in high temperature and low frequeucy range and another absorption (β) locates in low temperature and high frequency range. For amorphous samples as well as highly crystalline sample, position and apparent activation energy ΔH^* of the dielectric α absorption are nearly identical with those of the mechanical α absorption. In both dielectric and mechanical properties, α absorption of the crystallized sample shifts towards higher temperature and lower frequency and has smaller ΔH^* than that of the amorphous sample. Distribution of dielectric relaxation time τ or mechanical retardation time for α loss process of the crostallized sample is broader than that of the amorphous sample. ΔH^* for the dielectric β absorption which is independent of crystallinity is nearly equal to that for the mechanical β absorption. In series 2 as well as series 1, increase of crystallinity has many effects upon α absorption, such as decrease of the magnitude, shift of the position towards higher temperature and lower frequency, decrease of ΔH^* and ΔS^*, ΔF^* and the distribution of τ for β absorption are independent of crystallinity and only the magnitude decreases with increase of crystallinity. From the magnitude and quantitative analysis of end groups of the polymer chains, mechanism of β absorption is discussed.
- 社団法人日本材料学会の論文
- 1959-04-15
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