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ABSTRACT:Young's modulus of poly(ethylene terephthalate) (PET) film was estimated by using the generalized orientation factors of crystallites and amorphous chain segments calculated from the orientation functions of crystallites and amorphous chain segments. Theoretical analysis was carried out on the basis of a two-phase model assuring the homogeneous stress hypothesis for a polycrystalline material. In this model system, the anisotropic crystal phase is surrounded by the anisotropic amorphous phase. As the theoretical values of elastic compliance of crystal unit of PET, the values by Tashiro were adopted. The experimental values of Young's modulus at room temperature were in good agreement with the predicted value calculated by using the theoretical compliance. Furthermore, the ultimate value of Young's modulus was estimated by assuming an ideal simultaneous biaxially stretching film with 100% crystallinity and the perfect orientation of the c-axis as well as that of benzene rings parallel to the film surface. The predicted ultimate goal of the Young's modulus was less than 5 GPa indicating the difficulty in producing high modulus and high strength PET sheets in terms of theoretical aspects.

ABSTRACT:The orientation of the three principal crystallographic axes, the a-, b-, and c-axes of crystallites of poly(ethylene terephthalate) (PET) under simultaneous biaxial stretching was estimated in terms of the orientation distribution function. For most of crystalline polymers with a triclinic unit like PET, there are no crystal planes perpendicular to the a-, b-, and c-axes that can be detected directly by X-Ray diffraction techniques. Accordingly, the functions of the a-, b-, and c-axes must be calculated by the method proposed by Roe and Krigbaum. In doing so, the orientation functions of the reciprocal lattice vectors must be measured for a number of crystal planes. In this paper, as an example, the orientation of crystallites and the orientation of the a-, b-, and c-axes were estimated for a PET film under simultaneous biaxial stretching in terms of the orientation distribution function of crystallites because of considerable utilization rate of PET as commercial films. The estimated orientation functions of the b-and c-axes predicted the detailed information concerning uniplanner orientation of benzene rings parallel to the film surface. [DOI 10.1295/polymj.36.394] KEY WORDS The Three Principal Crystallographic Axes / Poly(ethylene terephthalate) / Simultaneous Biaxial Stretching / Orientation Distribution Function of Crystallites / Benzene Rings / The evaluation concerning molecular orientation was first proposed by Herman in terms of the second order orientation factor.1 This factor is a sort of the second moment of the orientation function. After then, the orientation of crystallites was estimated by Roe and Krigbaum 2-4 in terms of the distribution function. The mathematical representation was given by an expansion of the distribution function in a series of generalized spherical harmonics. This method has been very important to obtain the orientation of the three principal crystallographic axes, the a-, b-, and c-axes, in terms of the orientation distribution function. Actually, there are several papers for estimating orientation distribution functions of the three principal crystallographic axes, the a-, b-, and c-axes of polyethylene, 5,6 poly(vinyl alcohol), 7,8 nylon 6 9 and cellulose. 10The first trial for poly(ethylene terephthalate) by Krigbaum and Balta 11 was done by using a simple uniaxially stretched films but their trial was absolutely unsuccessful. However, the recent development of computer program and high power X-Ray source provide easy peak separation of overlapped peaks and the orientation functions for the reciprocal lattice vectors can be obtained for a number of crystal planes with high accuracy. Consequently it becomes possible to calculate the orientation distribution functions of crystallites as well as of the a-, b-, and c-axes from the observed orientation functions of the reciprocal lattice vectors of the crystal planes. In previous paper, 12 the orientation of crystallites with a triclinic unit was evaluated in terms of orientation distribution function for a PBT fi...

Composite films of polyethylene (PE) and polypyrrole (PPy) were prepared by polymerization of PPy on an ultradrawn polyethylene film with high modulus and high strength in ferric chloride (FeCl3) aqueous solution. The electrical conductivity of the composite film was found to be related to the polymerization conditions, such as polymerization temperature, polymerization time, the concentration and the oxidation potential of the FeCl3 solution. Scanning electron microscopy, FTIR and 13C NMR spectra were used to elucidate the morphological and structural variations of PPy prepared under different conditions, which lead to the differences in the electrical properties of the resultant composite films. The best electrical conductivity of the composite was about 5.5 S/cm for the film prepared under optimum conditions. The Young's modulus and the tensile strength reached 80 GPa and 3.2 GPa, respectively, which indicated the successful production of a conductive polymer with high strength and high modulus.