Dielectric Behavior of P(VDF-TrFE)/PMMA Blends L. O. FARIA, 1 R. L. MOREIRA 2 1 Centro de Desenvolvimento da Tecnologia Nuclear, R. Ma ´rio Werneck s/n C.P. 941, Belo Horizonte–MG 30123-270, Brazil 2 Departamento de Fı ´sica, ICEX, UFMG, C.P. 702, Belo Horizonte–MG 30123-970, Brazil Received 18 December 1998; revised 21 July 1999; accepted 30 July 1999 ABSTRACT: Binary blends of ferroelectric (vinylidene fluoride-trifluorethylene) copoly- mer [P(VDF-TrFE)] and amorphous poly(methyl-methacrylate) (PMMA) were investi- gated over the full range of composition, for the copolymer with 50 mol % of trifluor- ethylene. Dielectric measurements confirmed that the system becomes amorphous when the PMMA contents exceed 40 wt %. The observed dielectric losses could be attributed to the ferroelectric transition of the copolymer and to molecular relaxations, characteristic of the individual polymers. We demonstrate the thermally activated nature of the -PMMA and -P(VDF-TrFE) relaxations, with activation energies of 29.3 and 13.5 kcal/mol, respectively. We also demonstrate that the -P(VDF-TrFE) relax- ation cannot be attributed only to the copolymer glass transition and that its origin is not in the crystalline region, based on experimental evidences. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2996 –3002, 1999 Keywords: vinylidene fluoride-trifluorethylene copolymers; polymer blends; ferro- electric phase transition INTRODUCTION It has been reported in several studies 1–4 that semicrystalline (vinylidene fluoride-trifluorethyl- ene) copolymers [P(VDF-TrFE)] are miscible with poly(methyl-methacrylate) (PMMA), for various compositions. Because of their good optical prop- erties, which are very convenient for communica- tion technology, they have been proposed as can- didates for applications in such areas. In a recent work, 4 we demonstrated the strong influence of the composition and thermal history on the amorphous and crystalline phases of these blends, for a copolymer with 50 mol % of trifluor- ethylene (TrFE). Changes in the melting and fer- roelectric phase transition temperatures, as well as in the corresponding latent heats, were ob- served when varying these parameters, and were interpreted as a consequence of the crystalliza- tion kinetic and miscibility of the two compo- nents. Binary blends with crystalline and amorphous constituents, such as PVDF/PMMA, have been extensively studied, 5–11 leading to contradictory interpretations for the molecular mechanisms in- volved in some dielectric relaxation processes. In this work, we present the results of dielectric relaxation measurements of P(VDF-TrFE)/PMMA blends, covering the full range of composition, for the copolymer with 50 mol % of TrFE. Here, the ferroelectric phase transition of the copoly- mer 12–17 and the melting temperature depression of the blends give additional information about the blending process. EXPERIMENTAL PROCEDURES P(VDF-TrFE) copolymers with 50 mol % of triflu- orethylene, supplied by ATOCHEM (France), Correspondence to: L. O. Faria (E-mail: farialo@urano. cdtn.br) Journal of Polymer Science: Part B: Polymer Physics, Vol. 37, 2996 –3002 (1999) © 1999 John Wiley & Sons, Inc. CCC 0887-6266/99/212996-07 2996