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Thermally‐Induced Phase Transitions in the Uniaxially‐Oriented δ Form of Syndiotactic Polystyrene
Author(s) -
Gowd E. Bhoje,
Shibayama Naoya,
Tashiro Kohji
Publication year - 2006
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.200651035
Subject(s) - polystyrene , tacticity , solvent , materials science , molecule , phase transition , phase (matter) , polymer chemistry , endotherm , crystallography , chemical physics , chemical engineering , polymer , thermodynamics , composite material , chemistry , organic chemistry , differential scanning calorimetry , physics , polymerization , engineering
The empty δ (δ e ) form of uniaxially‐oriented syndiotactic polystyrene (sPS) samples were obtained by extracting the solvent molecules from the δ form of sPS and solvent complex in acetone and methanol. Temperature dependence of the X‐ray fiber diagrams starting from the uniaxially‐oriented δ e and δ form has been measured successfully at various temperatures for the first time. The transition behavior was traced clearly by separating the equatorial and layer line reflections. The δ e form transformed to the γ form via an intermediate form. The intermediate form is speculated to take disordered structure due to the empty cavities present in the δ e form. Calorimetric studies showed an endotherm followed by an exotherm during this phase transition, which is consistant with such a speculation. On the other hand the δ form transformed to the γ form directly without passing through the intermediate form or δ e form. During the δ to γ phase transition the solvent molecules evaporate through the columnar structure in a broad range of temperature, allowing the transition to occur smoothly.