Structural Evolution of PVDF under Heat and Pressure: Crystallinity and Phase Composition via FTIR and XRD AnalysisdissertationsWang, GuanlincreatorMathiowitz, EdithAdvisorMorgan, JeffreyReaderDarling, EricReaderBrown University. Biology and Medicine: Biotechnologysponsor2025, None p.born digitalThesis (Sc. M.)--Brown University, 2025thesesThis study investigates the synergistic effects of temperature (30–210°C) and pressure (10,000 lbs) on the crystalline phase evolution of poly(vinylidene fluoride) (PVDF), focusing on enhancing its electroactive β-phase content. Triplicate PVDF samples were processed under controlled thermal and pressure conditions, followed by structural characterization via X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Non-pressurized samples exhibited dominant α-phase crystallization (2–3% β-phase) below 150°C, with a minor β-phase increase (3–4%) near melting temperatures. In contrast, pressurized samples demonstrated accelerated β-phase nucleation, achieving 6–7% β-phase at 70–130°C and a peak of 9.6% at 170°C, near the α-phase melting point. This marked increase highlights pressure’s role in reducing energy barriers for all-trans chain alignment, stabilizing the polar β-phase. However, post-melting treatments (190–210°C) under pressure reverted β-phase content to baseline levels (1–2%), emphasizing that phase transitions are contingent on maintaining sub-melt conditions. Statistical reproducibility across triplicates confirmed robust trends. These findings underscore the potential of pressure-assisted thermal processing to tailor PVDF’s polymorphic behavior, offering a solvent-free pathway to enhance piezoelectric performance for applications in sensors and energy harvesting. The study bridges processing parameters with functional outcomes, providing actionable insights for optimizing PVDF’s electromechanical properties.PolymersEnglishRPB20250707