Effect of thermal and solution history on the Curie point of VF2-TrFE random copolymers

Abstract

The Curie transition in a VF₂‐TrFE random copolymer of fixed chemical composition (60/40 mol %) has been investigated as a function of processing history. Both solution cast and melt crystallized materials were investigated using differential scanning calorimetry and wide angle x‐ray diffraction. Results indicate that due to the higher solubility of TrFE units in dimethylformamide, dimethylacetamide, and cyclohexanone, solution cast films of VF₂‐TrFE yielded crystalline regions deficient of TrFE units. Upon annealing, a redistribution and equalization of the TrFE comonomer units within the crystalline regions was observed to occur resulting in a lowering of the Curie point. Melt crystallization, on the other hand, provided a more uniform distribution of TrFE units within the crystalline and amorphous regions, each having nearly the same proportion as in the overall composition. Subsequent annealing caused negligible changes in the Curie temperature.