Submillimetric study of a poly (vinylidene fluoride-trifluorethylene) copolymer under electrical and mechanical stresses

The infrared spectra of Poly (vinylidene fluoride) (PVDF) and copolymers in its different crystalline forms have been well explained in the frequency range 50 to 4000 cm"¹ [1/2]. Nevertheless, the submillimetric region (10 to 50 cm⁻¹) remains yet practically unexplored. In this region polymeric structures show broad absorption bands and rather poor polarization compared to single crystal structures. The absorption comes typically from intermolecular torsional modes, intermolecular motions in both amorphous and crystalline regions and relaxation processes from defects associated with the amorphous phase [3]. A few studies have been carried out but the interpretation of the spectra was rather delicate [4,5]. Frequently, apparent losses due to diffraction in the sample masks the true polymer absorption. In a previous paper we have described a theoretical model that allowed us to calculate the submillimetric absorption [6].