Crystallization behaviors and related dielectric properties of semicrystalline matrix in polymer-ceramic nanocomposites

Crystallization behaviors and related dielectric properties of semicrystalline matrix in polymer-ceramic nanocomposites have been systemically investigated by using P(VDF-TrFE) 70/30 mol.% as matrix and Ba0.5Sr0.5TiO3 nanoparticles as filler. It is found that due to the presence of ceramic nanofiller, there are two types of crystals formed in the matrix: one formed on the surface of the ceramic nanoparticles and the other formed in the polymer. The former favors the all-trans beta phase due to the interaction between matrix chains and ceramic surface. The later has defects that result in two low-temperature phases: the well-ordered beta phase and lessordered beta phase (i.e. beta ' phase). The conformation defects of the beta ' phase result in it a lower dielectric permittivity than beta phase. The proportion of beta' phase decreases with increasing ceramic content and only beta phase can be observed in the nanocomposites with a ceramic content higher than 35 vol%. These results were reflected in and confirmed by the DSC analyses and the dielectric properties.