Small Angle Light Scattering Studies on Biaxially Stretched Poly(ethylene terephthalate) Films obtained by Two-Way Successive Stretching Process

 

 

Hideaki Ishihara1, Miaki Shibaya2, Nori Yoshihara3, Chisato Nonomura4, Katsuya Ito5 and Tadashi Okudaira6

 

1.Division of Advanced Fibro-Science, Kyoto Institute of Technology,

Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan

Tel:81-75-724-7365  Fax:81-75-724-7800 
E-mail: h-ishi@ipc.kit.ac.jp

2. Division of Advanced Fibro-Science, Kyoto Institute of Technology,

Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan

Tel:81-75-724-7365  Fax:81-75-724-7800 
E-mail: b7330054@ipc.kit.ac.jp

3. Toyobo Co., Ltd. Research Center

2-1-1 Katata, Otsu 520-0292 Japan

Tel:81-77-571-0083  Fax:81-77-571-0084 
E-mail: nori_yoshihara@kt.toyobo.co.jp

4. Toyobo Co., Ltd. Research Center

2-1-1 Katata, Otsu 520-0292 Japan

Tel:81-77-571-0022  Fax:81-77-571-0023 
E-mail: chisato_nonomura@kt.toyobo.co.jp

5. Toyobo Co., Ltd. Research Center

2-1-1 Katata, Otsu 520-0292 Japan

Tel:81-77-571-0062  Fax:81-77-571-0118 
E-mail: katsuya_ito@kt.toyobo.co.jp

6. Toyobo Co., Ltd. Research Center

2-1-1 Katata, Otsu 520-0292 Japan

Tel:81-77-571-0061  Fax:81-77-571-0065 
E-mail: tadashi_okudaira@kt.toyobo.co.jp

 

 

Abstract

      This report is concerned with the studies on the stretching behaviors of poly(ethylene terephthalate) (PET) films obtained by the uniaxial and biaxial stretching methods. Studies are mainly concentrated on clarifying the high-order structure development and the structural change on stretching using Small-Angle Light Scattering (SALS) technique.

      On uniaxial stretching, a butterfly shape was obtained in the Hv light scattering pattern, which indicates the existence of a sheaflike crystalline high-order structure in the stretched films. Numerical calculations based on the sheaf array model were carried out for the interpretation of experimentally obtained SALS patterns. Results of the calculated patterns show good agreement with experimental ones.

      In the case of biaxially stretched films, the SALS patterns change remarkably depending on the stretching conditions and stretching systems. Higher stretching temperatures were found to be effective in the two-way successive stretching system since the high-order structure formed at the initial uniaxial stretching can’t be easily destroyed by the second stretching. Further, it became obvious that a three step stretching system in which machine direction stretching is divided into two steps is effective in obtaining biaxially stretched films having 8 leaf SALS patterns including the butterfly shape.

 

Key words: PET film, Two-way successive stretching, Small-angle light scattering, high-order structure, Computer simulation