Orientation Distribution Functions of the Three Principal Crystallographic Axes as well as Crystallites of Poly(ethylene terephthalate) Films under Biaxially Stretching

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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.

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confidence: 99%

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confidence: 99%

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

Bin

Oishi

Yoshida

et al. 2004

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“…Here it should be noted that the estimation of orientation of PBO crystallites with a triclinic crytsal unit is very complicated as discussed elsewhere for poly(buthylene terephthalate) 15 and poly(ethylene terephthalate) 16 films and nine crystal planes are needed to obtain the fourth order generalized orientation factor for calculating Young's modulus. This evaluation is practically impossible for PBO fibers.…”

Section: Methodsmentioning

confidence: 99%

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

Matsuo

Ishikawa

Xiang

et al. 2007

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ABSTRACT:In attempt to produce high modulus and high strength fibers with high electric conductivity, copper plating on the surface of poly(p-phenylenebenzobisoxazole) (PBO) fiber was carried out by using electroless plating, since PBO is a super-heat resistant polymer with the highest Young's modulus among polymers but is an insulator. The mechanical and electrical properties of the plated fibers were investigated as a function of copper content. At the maximum volume fraction of copper, ca. 30

“…In doing so, this paper adopts the orientation distribution functions of the reciprocal lattice vectors of crystal planes measured elsewhere. 11,12 The simultaneous biaxially stretching was carried out using ultra-high molecular weight polyethylene (UHMWPE) dry gel films prepared by gelation/crystallization from solutions.…”

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confidence: 99%

Segmental Orientation under Simultaneous Biaxially Stretching Using a Lattice Model and the Application of Oriented Crystallization of Polyethylene Films

Bin

Koganemaru

Nakashima

et al. 2005

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ABSTRACT:A lattice model proposed before for uniaxial stretching of polyethylene films was applied to estimate the oriented crystallization of ultra-high molecular weight polyethylene (UHMWPE) dry gel films under simultaneous biaxially stretching. In this model system, the preferred axis associated with the preferred orientation of amorphous chain segments was chosen along the direction between two successive cross-linked points and the preferred axis was assumed to deform in an affine fashion with respect to the stretching direction. As the application of the proposed model, the orientation distribution function of crystallites was calculated on the basis of the lattice model and oriented crystallization model. The oriented crystallization model is based on the concept that a kinetically determined distribution of crystal chain axes as the normalized distribution of clusters found at the saddle point corresponding to a non-uniform orientation under conditions of a steady-state nucleation rate. Of course, the crystallites are oriented randomly with respect to the film normal direction. The parameter fitting for the formulated orientation distribution function of crystallites was done for the film which was prepared by the gelation/crystallization from solution with 0.9 g/ 100 mL concentration, the solvent being decalin, since the concentration assured the highest drawability under simultaneous biaxially stretching. The calculated orientation distribution functions 2q j ðcos j Þ of the reciprocal lattice vector of the crystal planes were in good agreement with the observed ones. Thus the numerical calculations indicate that the orientation of the c-axes depends on that of amorphous chain segments and the orientation behavior of crystallites is strongly affected by their rotation around the c-axis. [DOI 10.1295/polymj.37.192] KEY WORDS A Lattice Model / Simultaneous Biaxially Stretching / Preferred Orientation / A Steady-State Nucleation Rate / Orientation Distribution Function of Crystallites / Segmental orientation in uniaxially deformed elastomatic networks has been treated in terms of gas-like theories and liquid-like theories.1-4 In the gas-like theories, the chain vector and segment vector distributions have been estimated theoretically by using idealized models in which the effect of mutual interference between chain segments are neglected. On the other hand, in a liquid-like theory, 3,4 the effect of intermolecular interferences relating to orientation-dependent packing entropy was taken into consideration based on a lattice model. Erman et al. 5,6 have attempted to improve the liquid-like theory by considering the effect of chain stiffness on segmental orientation. For this purpose, they adopted the lattice theory of Flory 7,8 for chains with freely jointed rod-like segments and applied it to a thermotropic system with anisotropic polarizabilities. Namely, Erman et al. pointed out that a segment of polyethylene chains with 1-22 bonds may be viewed as a rod-like object on the basis of the concept of Flor...