Chain Folding in the Smectic Phase of Main-Chain Polyesters.

Tokita, Masatoshi; Osada, Kensuke; Tsuchiya, Hitoshi; Watanabe, Junji

doi:10.1295/koron.56.184

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“…In the case of intrinsically rigid polymers, the equilibrium smectic-isotropic transition temperature T i ∞ is located at higher enough than the melting temperature of crystal phase, as was shown by Tokita et al 45,46 Whereas, the mesomorphic phase of intrinsically flexible polymer should exist in limitted conditions. Kawai and Kimura reported that molten iPP chains could be oriented under magnetic field up to 240 °C.…”

Section: Extrapolated Melting Temperature Of Mesomorphic Phasementioning

confidence: 76%

Crystallization of Isotactic Polypropylene from Prequenched Mesomorphic Phase

2006

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The crystallization process of isotactic polypropylene (iPP) by heating from the prequenched mesomorphic phase has been studied using wide-angle X-ray diffraction, small-angle X-ray scattering, and optical microscopy. Mesomorphic iPP as quenched shows the well-known nodular structure of ca. 100 Å. In heating process the nodules grew larger keeping self-similarity, with the mesomorphic phase partially transforming into the crystalline phase inside the nodules. After reaching the isothermal process, the nodules stopped to grow at a certain quasi-equilibrium size depending on the annealing temperature. During the long annealing, the interface among the nodules became obscure, and the nodules in nanometer scale merge into larger structure of pure R-phase in micrometer scale. The relation between the quasi-equilibrium nodule size and the annealing temperature leads an extrapolated melting temperature of the mesomorphic phase, which is located above the equilibrium melting temperature of the R-crystal.

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Section: Extrapolated Melting Temperature Of Mesomorphic Phasementioning

confidence: 76%