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Phase transitions in poly(heptane‐1,7‐diyl biphenyl‐4,4′‐dicarboxylate). SAXS, WAXS and DSC study
Author(s) -
Todorova Ginka,
Pérez Ernesto,
Marugán Mónica M.,
Kresteva Manya
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200450864
Subject(s) - small angle x ray scattering , thermotropic crystal , materials science , crystallinity , phase transition , differential scanning calorimetry , scattering , glass transition , amorphous solid , crystallography , phase (matter) , biphenyl , analytical chemistry (journal) , thermodynamics , polymer , optics , chemistry , organic chemistry , composite material , liquid crystalline , physics
The main‐chain thermotropic liquid‐crystalline poly(heptane‐1,7‐diyl biphenyl‐4,4′‐dicarboxylate) (P7MB) was investigated by time‐resolved small‐angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering (WAXS), and differential scanning calorimerty (DSC). Nonisothermal crystallisation with different rates of cooling and heating was used. On cooling, two phase transitions are observed, isotropic melt ‐ smectic (I‐Sm) and Sm‐ three‐dimensional crystalline structure (Sm‐Cr), whereas on heating only one transition is observed, Cr‐I transition. The transition enthalpies were calculated. Temperature dependences of d‐spacings of all crystalline peaks and of the peak observed at high values of scattering vector in the SAXS region were derived. The temperature dependence of the degree of crystallinity was established, based on the integrated intensities of the crystalline peaks and amorphous halo in WAXS.