Browsing by Author "Luo, Zhen-Hua"

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    Enhancement of polar phases in PVDF by forming PVDF/SiC nanowire composite
    (IEEE, 2016-12) Huang, Jie-Fang; Han, Song-Jia; Chen, Hui-Jiuan; Liu, Gui-Shi; Li, Gong-Tan; Wang, Yu-Cheng; Wang, Zi-Xin; Yang, Bo-Ru; Luo, Zhen-Hua; Shieh, Han-Ping D.
    Different contents of silicon carbide (SiC) nanowires were mixed with Poly(vinylidene fluoride) (PVDF) to facilitate the polar phase crystallization. It was shown that the annealing temperature and SiC content affected on the phase and crystalline structures of PVDF/SiC samples. Furthermore, the addition of SiC nanowire enhanced the transformation of non-polar α phase to polar phases and increased the relative fraction of β phase in PVDF. Due to the nucleating agent mechanism of SiC nanowires, the ion-dipole interaction between the negatively charged surface of SiC nanowires and the positive CH2 groups in PVDF facilitated the formation of polar phases in PVDF.
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    Flexible piezoelectric nano-composite films for kinetic energy harvesting from textiles
    (Elsevier, 2017-01-17) Almusallam, Ahmed; Luo, Zhen-Hua; Komolafe, Abiodun; Yang, Kai; Robinson, Andrew; Torah, Russel; Beeby, Steve
    This paper details the enhancements in the dielectric and piezoelectric properties of a low-temperature screen-printable piezoelectric nano-composite film on flexible plastic and textile substrates. These enhancements involved adding silver nano particles to the nano-composite material and using an additional cold isostatic pressing (CIP) post-processing procedure. These developments have resulted in a 18% increase in the free-standing piezoelectric charge coefficient d33 to a value of 98 pC/N. The increase in the dielectric constant of the piezoelectric film has, however, resulted in a decrease in the peak output voltage of the composite film. The potential for this material to be used to harvest mechanical energy from a variety of textiles under compressive and bending forces has been evaluated theoretically and experimentally. The maximum energy density of the enhanced piezoelectric material under 800 N compressive force was found to be 34 J/m3 on a Kermel textile. The maximum energy density of the enhanced piezoelectric material under bending was found to be 14.3 J/m3 on a cotton textile. These results agree very favourably with the theoretical predictions. For a 10x10 cm piezoelectric element 100 µm thick this equates to 38 μJ and 14.3 μJ of energy generated per mechanical action respectively which is a potentially useful amount of energy.
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    Novel thick-foam ferroelectret with engineered voids for energy harvesting applications
    (IOP Publishing: Conference Series / Institute of Physics (IoP), 2016-12-14) Luo, Zhen-Hua; Shi, J.; Beeby, S. P.
    This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications.