Poly (ethylene terephthalate) (PET) fibers containing poly (oxyethylene) (PEO) were prepared to study the molecular weight effect of PEO upon antistatic property. A series of fibers containing 2wt% of PEO with molecular weight M_n=4, 000 (PEO (4)), 20, 000 (PEO (20)), and 100, 000 (PEO (100)) as well as the fiber containing 10wt% of PEO (20) were spun by a melt spinning at 270°-280°C, and then submitted to 4.9-fold drawing and heat-treated at 170°C. Each fiber was washed in a boiling water for 1hr.
Observation of the transversal sections of the unwashed fibers by light (LM) and scanning electron microscopes (SEM) showed that PEO particles are distributed in the PET matrix. The particle size of PEO in the as-spun fibers increased markedly with increasing the M_n, and its size and number decreased after drawing. The antistatic property of the drawn fibers evaluated by half-lifetime of leakage of static charge was improved with the increase in PEO's M_n. Therefore, this tendency is to be explained in connection with its particle size. The particle size in the sample containing 10wt% PEO (20) was the same as that in the sample containing 2wt% PEO (20), though the number was much larger than that of the latter sample. For the both fibers, the antistatic properties before washing were in the same level.
The LM and SEM photographs of the washed fibers indicated that PEO particles bled out from the interior of fiber, with the fibers' inner structure being porous. This observation is correlated with the deterioration of antistatic property after washing. The rate of bleed-out of PEO (20), however, was somewhat slower than that of other PEOs, i.e., the PEO (20) particles still remained on the fiber surface after washing. This may explain the fact that the antistatic property of the fiber containing PEO (20) was unchanged or improved after washing.
The viscoelastic nature of those blend fibers was also examined. It showed that the compatibility of PEO with PET decreased with the molecular weight increase of PEO. A tendency to deterioration of mechanical properties of the blend fiber is consistent with this incompatibility. It can be concluded from these findings that blending about 2wt% PEO (20) is the most effective as far as homopolymer of PEO is used for antistatic modification of polyester.

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目的 単一の緩和時間で構成される系について, tanδ-温度 (T) 曲線の理論式を導き, この式にしたがってtanδ-T 曲線を計算する, この計算結果を利用し, 実測のtan δ-T 曲線の解析方法を示す.
結果 tanδ-T曲線でピークを与える粘弾性モデルとして, Maxwell要素に並列に弾性要素を加えた三要素モデルが採用できる. 緩和時間の温度依存性としてWLF型とアレニウス型の2種を仮定して計算されたこの三要素モデルのtanδ-T曲線より, 以下のことが明らかとなった.
(1) tanδ-T曲線の半価幅ΔT1/2(3) はtanδ のピーク温度位置Tmax (K) とこの温度での見掛けの活性化エネルギΔHa (kcal/mol) との間に次式の関係がある.
ΔT1/2(3)=5.24×10-3Tmax/ΔHa
(2) log tanδ-T曲線は2等辺3角形で近似できる.
(3) β ∞=522ΔHa/Tmaxで定義されるパラメータ B ∞ の値を採用すれば, 粘弾性吸収機構が決定できる.
(4) 無定形領域内のセグメントのミクロブラウン運動に関係した吸収, aa 吸収, および鎖の局所的運動に関係した吸収, βa 吸収の各種高分子についての平均のΔT1/2 (3) は約13 deg および 20 deg で βa 吸収の方が大きい.
(5) ΔHa とTmaxよりTqにおける緩和時間を評価できる.

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Infrared absorption and dynamic loss tangent (tan δ) measurements were made on poly(ethylene terephthalate) to study the microstructure of the amorphous part which induced Case II swelling. Unoriented films crystallized by various methods including annealing to attain a wide variety of crystallinity were used as samples.
Case II swelling was independent of the amount of regular folding. It was inferred that the microstructure contains a large amount of ethylene glycol residue in trans conformation and is included in well-formed spherulites. The α_a absorption in tan δ behavior, which is related to the microbrownian motion of chain segments in amorphous region, indicates that the texture may consist of the chain segments of highly elastic character.

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