ポリプロピレン結晶の粘弾性的性質
1967 年 16 巻 166 号 p. 552-556
詳細
1967 年 16 巻 166 号 p. 552-556
The solution grown crystals of polypropylene prepared from xylene dilute solution show a larger crystalline absorption peak in the temperature dependence of dynamic loss modulus than that of the melt crystallized bulk specimen. The solution grown crystals are effective in studying the viscoelastic properties of the polymer crystals. In order to make clear the relationship between the morphology and viscoelastic properties of the polymer, it is further necessary to clarify the characteristics of the crystals in the bulk crystallized specimen.
The tensile dynamic and loss moduli, E' and E" of the mats of crystals grown in dilute solution and those obtained by an acid etching of the bulk crystallized specimen, were measured at a frequency of 110c/s over a temperature range from -20 to 170°C by using a direct reading dynamic viscoelastometer, Vibron DDV-II.
The crystalline absorption peak of the solution grown crystal precipitated at 90°C, whose degree of crystallinity and crystal perfection was higher than that of the crystals precipitated at 70 and 80°C., appeared at higher temperature than the others without decreasing the peak intensity. The degree of crystal perfection of the crystal precipitated at 70°C could be increased by annealing. In this case, however, the intensity of crystalline absorption peak decreased, when the annealing temperature was taken above 135°C.
The crystal obtained from the acid etching of annealed bulk specimen below 135°C showed almost the same viscoelastic behavior as that of the solution grown crystal. Therefore, the less intensive crystalline absorption peak of the melt crystallized bulk specimen could be attributable to the existence of amorphous region between the crystal lamellae. On the other hand, the decrease of the crystalline absorption peak, as pointed out above, for the crystal annealed above 135°C could not be explained in terms of the two phase model composed of amorphous and crystalline phases, and would have to be attributed to the properties of the crystal itself.
