1986 年 35 巻 396 号 p. 1066-1070
Elastic moduli of the crystalline region of polytrimethylene terephthalate (PTT) have been measured by the X-ray diffraction method. The elastic modulus parallel to the chain axis, El, was 2.59GPa, and this value of El is the smallest as compared with those already reported. This is reasonable, judging from the crystal structure of PTT which consists of a highly contracted conformation of molecular chain. The chain extension is considered to occur mainly by the internal rotation of methylene groups. The elastic modulus of the bulk specimen increased with increasing draw ratio and was found to reach to the value of El at the draw ratio over 3.3.
On the other hand, the elastic modulus perpendicular to the chain axis, Et, was 3.8GPa. Since many other polymers have been found to exhibit larger El than Et, PTT is unique in this respect, and it has a characteristic crystal structure in which the intermolecular force has larger effect against deformation than the force holding the contracted molecular conformation.