Thermal degradation and optical characteristics of plasticized poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate) terpolymer

Casting method was employed to prepare films of poly(vinyl chloride-co-vinyl acetate-co-2-hydroxypropyl acrylate) (PVVH) terpolymer doped with different amounts of tetrabutylammonium tetrafluoroborate ([TBA][BF₄]) electrolyte. The interaction between terpolymer and electrolyte was evident in the shift and reduction of the ATR-FTIR peak intensities of the C–Cl stretching vibrations at 613 cm⁻¹ and 688 cm⁻¹ with increasing electrolyte concentration. The effect of electrolyte was also visible in the reduction of DTG/DTA peak temperature (T_p) of the second stage of the composites. The decrease of the DSC glass transition temperature (T_g) from 344 K to 310 with increasing electrolyte content indicates the plasticization effect of the electrolyte that reduces the inter- and intramolecular interaction maintaining the flexibility of the PVVH terpolymer backbone to bend and slide more readily. The kinetics of thermal degradation of pure compounds and their composites were investigated and discussed in terms of the Coats–Redfern approach. The results revealed an increase in the activation energy of thermal degradation with increasing the electrolyte content. Linear and nonlinear optical parameters were calculated and discussed in terms of the single oscillator model and Miller's rule. The visible and UV transmittance of the investigated materials demonstrated values of 91% and 5%, respectively. Furthermore, they achieved reflectance of 3 and 58% in the visible and UV regions, respectively, making these composites an excellent candidate for optical applications. Besides, the optical conductivity (σ_op) and dielectric constant of all samples were investigated.