Ferroelectrics, 294: 61–71, 2003 Copyright c  Taylor & Francis Inc. ISSN: 0015-0193 print / 1563-5112 online DOI: 10.1080/00150190390238621 Mechanical Characterization and Influence of the High Temperature Shrinkage of β-PVDF Films on its Electromechanical Properties V. SENCADAS, 1 R. BARBOSA, 1 J. F. MANO, 2 and S. LANCEROS-M ´ ENDEZ 1,∗ 1 Dept. de F´ ısica, Universidade do Minho, 4710-057 Braga, Portugal 2 Dept. de Eng. de Pol´ ımeros, Universidade do Minho, 4800-058 Guimar ˜ aes, Portugal (Received September 4, 2002; In final form December 15, 2002) Tensile dynamic mechanical analysis at 1 Hz was used to characterize the solid rheological properties of β-PVDF films. Both the elastic and loss moduli and the specific damping capacity were monitored against temperature, allowing the study of the effect of anisotropy upon the viscoelastic properties of the films. The temperature range covered the β- and α-relaxations. These results are compared to dielectric relaxation results in order to elucidate the electrical and mechanical contributions to the observed relaxations. Further, an important shrinking effect upon heating above 364 K has been observed, that influences the material properties. This geometrical effect has been monitored by thermal mechanical analysis. The thermal coefficients of linear expansion have been calculated, giving two different regimes for this parameter. The variations at a molecular level have been monitored by FTIR. Keywords: PVDF; dielectric relaxation; mechanical relaxation; infrared 1. INTRODUCTION Ferroelectric polymers are both of great scientific and technological interest. The rapid commercialization of piezoelectric transducers made from these materials also a model for technology transfer. Ferroelectric polymers are a rich system for the study of phase transitions, relaxational processes and ferroelectricity; they exhibit all the interesting physical phenomena asso- ciated with inorganic ferroelectrics and yet exhibit fundamentally different microscopic interactions, dominated by the hydrogen bonding and the van der Waals forces [1]. ∗ Correspondence address. E-mail: lanceros@fisica.uminho.pt [417]/61