Mechanical Properties and Fine Structure of Polypropylene Films
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概要
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The static and dynamic mechanical properties of the films of polypropylene fractions which encompass a wide range in molecular weight and crystallinity have been studied.<BR>The fractionation was conducted by a conventional column elution method, utilizing kerosine as a solvent and butyl cellosolve as a nonsolvent. Two kinds of method have been used for the fractionation. One, a gradient elution fractionation at 150°C, fractionates according to molecular weight, the other, elution with one solvent at increasing temperatures, separates according to crystallinity.<BR>In general, yield stress, tensile strength and Young's modulus of the fractions depended on the crystallinity, while elongation at break depended not only on the crystallinity but also on the molecular weight.<BR>The temperature dependency of dynamic modulus and loss tangent of annealed fractions as well as whole polymer which had been quenched quickly from the melt, or annealed after the quenching, or cooled slowly from the melt to room temperature was measured in the temperature range from -50°C to +120°C by the vibrating reed method.<BR>The absorption curve of tanδ in the vicinity of room temperature was studied particularly in relation to the fine structure and molecular structure of the polymer.<BR>In the series of experiments with well-annealed fractions, it was observed that the height and width of the absorption band generally became lower and wider in accordance with the increase of crystallinity, and the temperature T<SUB>α</SUB>, where tanδ went through a maximum, shifted to a higher temperature.<BR>Furthermore, in studying the effect of thermal history on the dynamic mechanical properties of the polymer, it was found that a quenched sample without annealing had a higher value of T<SUB>α</SUB> and a wider absorption band than those of well-annealed ones.<BR>It seems that these experimental results can be well interpreted by the following assumptions; 1) the peak of tanδ in the vicinity of room temperature is attributed to microbrownian motion of the main chain segments in the amorphous region as accepted generally; 2) the value of tanδ at a temperature corresponds to the amount of segments which begin to move at the temperature; 3) T<SUB>α</SUB> depends on the extent to which the motion is being restricted by the fine structure of polymers; 4) the width of the absorption band depends on the variety of the extent of the restriction.
- 公益社団法人 高分子学会の論文
公益社団法人 高分子学会 | 論文
- 情報の入口--高分子センサ-とトランスデュ-サ- (情報化社会と高分子)
- 高分子科学最近の進歩--メルトレオロジ-(伸長粘度)
- 高分子系の相分離--特にポリマ-ブレンドについて
- 導電性高分子の磁気緩和--NMRT-1〓1の周波数依存性
- 多機能性高分子の合成 (化学修飾による多機能性高分子)