Influence of Six Plasticizers on the Morphology, Crystallinity, and Thermal Properties of Poly(Vinylidene Difluoride) Films

Abstract

Poly(vinylidene fluoride) (PVDF) is renowned for its durability but suffers from limited flexibility, restricting its use as a protective topcoat on architectural textiles. This study investigated six ester-based plasticizers at a loading of 50 wt% in a 10 wt% PVDF solution (dissolved in dimethylacetamide at 50°C) to identify an optimal candidate for enhancing flexibility while maintaining suitable morphology. DSC indicated that P3 (dibutyl phthalate) lowered the polymer's melting temperature to 154°C (from 170°C for pure PVDF) and decreased its glass transition temperature (T_g) to −81.5°C. However, SEM revealed significant porosity, undermining its protective function. In contrast, P2 (di(propylene glycol)dibenzoate) resulted in a 10°C reduction in melting temperature and a 19°C reduction in crystallization temperature, yet only increased T_g by 3°C; the film remained more flexible than unmodified PVDF. SEM confirmed minimal voids, indicating good compatibility. Furthermore, DSC data demonstrated P2 raised the degree of crystallinity from 31% in the reference film to 34% while preserving structural integrity. These findings highlight P2 as the most viable plasticizer for producing flexible PVDF topcoats, offering a simpler, cost-effective solution with the potential to extend the lifespan of architectural textiles in under-resourced regions.