We report the piezoelectric, dielectric and dynamic mechanical features of nanohydroxyapatite (nHA) embedded ethylene-covinyl acetate (EVA)/millable polyurethane (MPU) elastomer blends. The EVA/MPU/nHA systems were prepared by two-roll milling followed by compression moulding. The piezoelectric features were probed by dynamic contact electrostatic force microscopy (EFM).The neat EVA/MPU blend was not found to exhibit ferroelectric properties. However, upon incorporation of nHA, butterfly loops of EFM amplitude signals as well as complementary hysteresis curves were obtained, confirming the introduction of ferropiezoelectric properties. The ferro-piezoelectric features were found to be improved with an increase in nHA loading which recorded highest signals for 8 parts per hundred parts of rubber (phr) loaded composites. The fabricated devices generated a peak voltage of 4.02 V and 4.89 V respectively with 6 phr and 8 phr nHA loaded composites. Electrical properties such as dielectric constant, volume resistivity and loss factor as well as dynamic mechanical properties were examined. The viscoelastic features of the systems support the reinforcing feature with filler loading. TEM analysis of the composites indicated a uniform distribution of filler particles in the blend matrix, complementing the observed ferro-piezoelectric, dielectric and dynamic mechanical properties. The simultaneous modulation of piezoelectric and viscoelastic properties is a preferred feature for fast-responsive dielectric elastomers for their applications in various piezoelectric devices.

No abstract

No abstract

No abstract

Piezoelectric materials have gained interest among materials scientists as body motion sensors and energy harvesters on account of their fast responsiveness and substantial output signals. In this work, piezoelectric polymer mats have been fabricated from ethylene-co-vinyl acetate–millable polyurethane/nanohydroxyapatite (EVA–MPU/nHA) composite systems by employing the electrospinning technique. The ferro-piezoelectric features of the samples were confirmed from the butterfly loops of electrostatic force microscopy (EFM) amplitude signals as well as through the hysteresis curves of the EFM phase recorded with the assistance of dynamic-contact EFM. Piezoelectric responses of the samples to random finger tapping were evaluated after fabricating a simple device prototype connected to an oscilloscope. The efficacy of the mats to generate a voltage in response to activities such as mechanical bending, movement of throat muscles while drinking, movement of elbow joints, air blowing, and so forth has also been investigated. The results suggest the promising possibility of fabricating user-friendly piezoelectric mats out of the EVA–MPU/nHA system for physiological motion-sensing applications.