Electrostrictive poly(vinylidene fluoride-trifluoroethylene) copolymers

Work-per-cycle analysis for electromechanical actuators

“…The actuator strain and elastic modulus data included in Table 1 represents typical values for each material and has been obtained from Cheng et al [9] for piezoceramics (PEC) and electrostrictive polymers (ESP); Pelrine et al [10,11] for electrostatic elastomers (ESE) and from our own laboratories for polypyrrole (PPy) and carbon nanotube actuators (CNT). Figure 5 shows the work-per-cycle of the actuators operated isotonically (ignoring the preload stretch) and operated against a restoring spring.…”

“…The predicted result for piezoelectric ceramics (29 kJ/m 3 ) is somewhat different to literature values. In the work by Cheng et al [9] the work capacity is over-estimated by simply taking the product of Y 0 2 /2 rather than using equation (27). The work by Giurgiutiu [2] gives a highest work capacity of 12 kJ/m 3 which is only half the predicted value since the actuators used in their study (from various commercial sources) only produced ~0.1% strain which is ½ that assumed in the calculated results given in Table 1.…”

Dielectric composites with a high and temperature-independent dielectric constant

“…For example, the dielectric constant of P(VDF-TrFE) can reach up to 80 at the ferroelectric-to-paraelectric phase transition temperature [15], which is more than 7 times of that at room temperature. The ferroelectric-to-paraelectric phase transition temperature in P(VDF-TrFE) ranges from 60 ℃ to 150 ℃ depending on the composition [16]. Therefore, the dielectric properties of a composite made of polar polymer matrix and/or polar filler are strongly dependent on the temperature.…”

Synthesis and microstructure of a novel graft copolymer from poly(vinylidene fluoride–chlorotrifluoroethylene–trifluoroethylene)

“…Among these crystalline phases, the polar β-phase is the most interesting and important one because it exhibits a strong ferroelectric behavior. [10][11][12] In order to obtain high performance and inexpensive electroactive polymers (EAPs), many efforts have been made to modify the crystal structure and morphology in the PVDF-based polymers, including studies of the effects of irradiation on PVDF-based copolymer [13][14][15][16] and terpolymers, [17][18][19][20] PVDF-based composites, [4,[21][22][23] and PVDFbased polymer blends with thermal treatment. [24][25][26] However, as an important method of modifying polymers, graft copolymerization of comonomers from the backbone of these ferroelectric fluoropolymers was seldom adopted to prepare high performance EAPs.…”