Poly(vinylidene fluoride) and vinylidene fluoride-tetrafluoroethylene copolymers cocrystallize depending on the structures present in each. In the or-phase, the maximum difference in the defect concentration of the two polymers (A defect) equals 12.3% during isothermal crystallization, and is equal to 10.5% when the system is quenched. In the/y-phase, it is 1 !.8% for isothermal crystallization, and ~ 5.5% when quenched. Apart from isomorphic cocrystallization between components of the same polymorph, cocrystal formation between the :t- and /y-polymorphs was also observed. The resulting cocrystal adopts the structure of a particular polymorph, according to the results obtained from potential energy calculations. The interplanar spacings (dhkt) of the :t-phase of PVF 2 do not change with the H-H defect concentration, but for the/y-phase d2oo increases with the defect concentration. The reason for this difference in behaviour has been attributed to the more compact nature of the fl-polymorph unit cell, when compared to that of the ct-polymorph. The limiting value of the A defect for cocrystallization in the or-phase has been attributed to the larger difference in the intramolecular potential energy, whereas that of the/Y-phase has been attributed to the compact nature of the unit cell
Посилання на статтю:
Cocrystallization of poly(vinylidene fluoride) and vinylidene fluoride-tetrafluoroethylene copolymers: 1. Effect of chain structure and crystallization conditions / Jhunu Datta and Arun K. Nandi // Polymer. – 1994. – Vol 35. – P. 4804-4812.