Crystallization kinetics and phase transformation of poly(vinylidene fluoride) films incorporated with functionalized baTiO_3 nanoparticles

摘要

The transformation of α to β-phase in poly(vinylidene fluoride) (PVDF) induced by the addition of tetradecylphosphonic acid (TDPA)-BaTiO_3 nanoparticles and subsequently the isothermal crystallization kinetics of pristine PVDF and its nanocomposites have been investigated. The result of infrared spectra showed that the relative crystalline fraction of β-phase was enhanced greatly after the introduction of TDPA-BaTiO_3 nanoparticles, and reached the peak of 93% when the concentration of nanofillers was 20%. The interaction between TDPA-BaTiO_3 nanoparticles and PVDF macromolecular chains induced the change of conformation from trans-gauche to all-trans crystal structure in PVDF segment. The isothermal crystallization of TDPA-BaTiO_3/PVDF nanocomposites was carried out by the differential scanning calorimetry (DSC). The influence of TDPA-BaTiO_3 nanoparticles concentration on crystallization rate, activate energy, melting enthalpy, and peak temperature were studied. The nanocomposite film loaded 20% TDPA-BaTiO_3 nanoparticles exhibited the highest crystallization rate and activate energy, which decreased after loading more nanofillers in the host because of high volume fraction of nanoparticles leading to steric hindrance and further weakening the mobility of PVDF chains during the crystallization.