Effect of Poly (N- Vinypyrrolidone) on the Non-Isothermal Crystallization Kinetics and Viscoelastic Properties of PVDF Films

Abstract

-Poly(vinylidene fluoride) (PVDF) and PVDF blends with various molecular weights of poly (Nvinylpyrrolidone) (PVP) films were prepared in dimethyl formamide through the solution casting method. Non-isothermal melt crystallization studies of PVDF films were carried out by cooling the molten samples at different temperatures using differential scanning calorimetry (DSC). The obtained films have been characterized by dynamic mechanical thermal analysis (DMTA). Crystallization kinetics of PVDF films were successfully described by the Jeziorney, Mo and Ziabicki models. The Ozawa equation was found to be invalid for describing the crystallization kinetics. Kinetic parameters such as t 1/2 , Z c and F(T) indicated that the crystallization rate decreased for PVDF/PVP films as compared to neat PVDF films and was affected by the molecular weight of PVP. The results based on Ziabicki's model revealed that the addition of PVP decreased the ability of PVDF to crystallize under non-isothermal melt crystallization conditions. The activation energy was calculated through Friedman and advanced isoconversional methods. Results showed that the addition of PVP to PVDF films caused an increase in activation energy. By comparing DMTA results of PVDF/PVP blends with neat PVDF films, it could be concluded that blending PVDF with PVP caused an increase in the glass transition temperature (T g ) while the storage modulus was decreased.

Calorimetric and rheokinetic analyses merged to capture crystallization kinetics in polyamide/clay nanocomposites: Revisiting predictability of models

“…Moving from regime I to regime II, the rate of the surface nucleation of the crystallization substrate ascends and approaches complete rate of crystallization substrate (chain diffusion) in regime II [Figure (B)] . Values of n 1 (lower than 1.5) are unusual and hardly attainable for polymeric samples, for the reason that when polymers crystallize in lamellar aggregates, there are at least two‐dimensional lamellas.…”

Polyvinylidene fluoride–Hyaluronic acid wound dressing comprised of ionic liquids for controlled drug delivery and dual therapeutic behavior

“…The average number of moles of Clper mole of each API-IL was found to be below 2%, confirming that the reaction was complete. The chemical structures of the prepared API-ILs were confirmed by 1 H and 13 C NMR spectroscopy and elemental analysis. NMR spectra were recorded using a Bruker Avance 300 (France) at 300.13 MHz, using dimethyl sulfoxide (DMSO) as solvent and tetramethylsilane (TMS) as internal reference.…”

“…To obtain reservoir-type wound dressings, synthetic polymers such as polypropylene (PP), polyethylene (PE), polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), poly(lactic-coglycolic acid) (PLGA), and polyvinylchloride (PVC) have been used [11,12]. Polyvinylidene fluoride (PVDF) is a chemically and thermally stable, hydrophobic polymer with high mechanical strength and piezoelectric properties and widely used in the biomedical field [13].…”