Novel three-dimensional nano-oriented crystals of polyesters

K. Okada1, Y. Tanaka2, H. Masunaga3, and M. Hikosaka1

1Graduate school of integrated arts and sciences, Hiroshima University, Japan.
2Teijin Ltd., Japan.
3Japan synchrotron radiation research institute (JASRI), SPring-8, Japan.

We crystallized the supercooled melt of polyesters by the melt-elongation. We used three kinds of polyesters, such as poly(ethylene terephthalate); PET, poly(ethylene-2,6-naphthalene dicarboxylate); PEN and poly(butylene terephthalate); PBT. We found that the novel three-dimensional (3D) morphology of “nano-oriented crystals (NOCs)” was formed, while in the case of isotactic polypropylene, one-dimensional morphology of NOCs was formed [1,2]. We observed the structure and morphology of NOCs by means of polarizing optical microscope, small/wide angle X-ray scattering. The nano crystals of 10 nm in order showed single crystal like monoclinic arrangement. The molecular chains were mainly oriented along the elongational direction. We clarified the mechanism of formation of 3D-NOCs of polyesters and an important role of the Benzene plane. In the elongational flow, the Benzene planes will be arranged by the effect of hydrodynamics [3] and packed locally in parallel. The parallel-packed Benzene planes should become a precursor of a nucleus, which would result in homogeneous nucleation [4] and formation of 3D-NOCs.

[1] K. Okada et al., Polymer J. 42, 464 (2010). (link)
[2] K. Okada et al., Polymer J. 45, 70 (2013). (link)
[3] T. Tatsumi, Ryutairikigaku, p.171 (Baifukan Co. Ltd., Tokyo, Japan, 1982).
[4] F. P. Price, in Nucleation (ed. A. C. Zettlemoyer) Ch.8 (Marcel Dekker, Inc., New York, USA, 1969).