CURIE TRANSITION AND PIEZOELECTRICITY OF THE BLENDS OF A FERROELECTRIC VDF/TRFE COPOLYMER AND PMMA

The Curie transition, even though the conformational change at the Curie transition primarily arises from intermolecular interaction, is highly dependent on the crystallization conditions. A slower cooling rate from the melt during paraelectric crystallization lowers T(c), increases the portion of F(beta) at the expense of F(alpha) reduction, and produces a more unstable ferroelectric phase. T(c)down is rarely dependent upon the amount of PMMA, but T(c)up is increased with the PMMA content. PMMA has a favorable action in forming a more stable ferroelectric phase in the P(VDF/TrFE)/PMMA blend and elevating the Curie transition point because of the all-trans sequence conformation of PMMA and a specific intermolecular interaction with P(VDF/TrFE) in the melt state. However, PMMA reduces the total amount of the crystalline phase, the electric response, and the piezoelectricity.