Mechanical Properties of Poly(ethylene terephthalate) Estimated in Terms of Orientation Distribution of Crystallites and Amorphous Chain Segments under Simultaneous Biaxially Stretching

Abstract

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.

Morphology and High Modulus of Laminated Ultra‐Drawn Polyethylene Films with Biaxial Orientation Prepared by Microwave Heating

“…However, the reported maximum Young's modulus of biaxially ultradrawn films is less than 6 GPa, which is much lower than the experimental value (225 GPa) of uniaxially ultradrawn films. [3] The same phenomena have been confirmed for biaxially stretched poly(vinyl alcohol) (PVA) [11] and poly(ethylene terephthalate)(PET) [12] films. In a recent study, Matsuo et al adopted an anisotropic continuous mechanical theory to calculate the ultimate Young's modulus of PE, [3,5] PVA [11] and PET [12] for an ideal simultaneous biaxially stretched film with 100% crystallinity, in which the c-axis and a particular crystal plane with the highest atom density are oriented perfectly parallel to the film surface.…”

“…[3] The same phenomena have been confirmed for biaxially stretched poly(vinyl alcohol) (PVA) [11] and poly(ethylene terephthalate)(PET) [12] films. In a recent study, Matsuo et al adopted an anisotropic continuous mechanical theory to calculate the ultimate Young's modulus of PE, [3,5] PVA [11] and PET [12] for an ideal simultaneous biaxially stretched film with 100% crystallinity, in which the c-axis and a particular crystal plane with the highest atom density are oriented perfectly parallel to the film surface. To pursue the theoretical calculation of the ultimate Young's modulus, the elastic compliances of the crystal unit calculated for polyethylene by Odajima [13] and for PVA [14] and PET [15] by Tashiro were adopted.…”

“…Nevertheless, this value is higher than the ultimate value (4.73 GPa) of such an ideal PET film with 100% crystallinity, calculated on the assumption that the c-axes and the benzene rings take a perfect uni-planar orientation to the film surface, but a random orientation with respect to the film thickness direction. [12] The Young's modulus increased symmetrically apart from along the 45 8 direction. Along the 22.5 and 67.5 8 directions, the values were higher than 10.2 Gpa, which is higher than the ultimate value (9.58 GPa) of an ideal simultaneous biaxially stretched PE film [10] and that (4.73 GPa) of the corresponding PET film.…”

“…The calculated values for the ultimate Young's moduli of these polymers were 9.58GPa for PE, [10] 13.5 GPa for PVA [11] and 4.73 GPa for PET. [12] The formulated equations indicated that the Young's modulus of the ideal simultaneous biaxially stretched film is strongly affected by the shear components of the elastic compliance (or stiffness) of the crystal unit. This paper deals with the improvement of the poor mechanical properties of uniaxially ultra-drawn films along the transverse direction by the lamination of two ultra-drawn films set in such a way that the stretching directions intersect each other.…”

High Modulus and High Strength Fibers with High Electric Conductivity Prepared by Copper Electroless Plating on the Surface of Poly(p-phenylenebenzobisoxazole) (PBO)

“…The tensor description between the intrinsic compliance of the structural unit and the bulk compliance is given by [12][13][14][15][16][17] …”