Biopolymer Composites With High Dielectric Performance: Interface Engineering
01 Jan 2017-pp 27-128
TL;DR: In this article, the preparation and dielectric behavior of various biopolymer composites is presented, including metal nanoparticles and carbon-based nanofillers such as carbon nanotubes, graphene, etc.
Abstract: In recent years, there is a growing interest in studying the dielectric behavior of biopolymer composites due to their potential application as a dielectric material in various electronic devices such as microchips, transformers, and circuit boards. Conducting electroactive polymer composites have also been investigated for various potential applications which include biological, biomedical, flexible electrodes, display devices, biosensors, and cells for tissue engineering. In this chapter, the preparation and dielectric behavior of various biopolymer composites is presented. These biopolymer composites generally consist of nanoscale metal nanoparticles and carbon-based nanofillers such as carbon nanotubes, graphene, graphene oxide (GO), etc., dispersed into the polymer matrix. The physical and chemical properties of these fillers and their interactions with polymers have a significant effect on the microstructure and the final properties of nanocomposites. The biopolymer composites with excellent dielectric properties show great promise as an energy storage dielectric layer in high-performance capacitor applications such as embedded capacitors. This chapter highlights some of the examples of such biopolymer composites; their processing and dielectric behavior will be discussed in detail.
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TL;DR: In this article, the growing medium was modified in order to produce bacterial cellulose (BC) nanocomposites using a bottom-up technique that allowed starch to be introduced into the cellulose network.
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55 citations
TL;DR: The incorporation of pH indicator dyes to the montmorillonite bio-nanocomposite films allows their application for optical pH sensing and the possibility to be processed as homogeneous thin films provided of good mechanical properties and transparency.
Abstract: Clay minerals such as the layered silicates montmorillonite and vermiculite, as well as the fibrous clay sepiolite, and a layered double hydroxide ([Zn2Al(OH)6]Cl.nH2O) have been used to prepare gelatin-clay micro- and nano-composites. This biopolymer can be assembled to those inorganic solids through interactions at the nanometric range, but only in the case of montmorillonite intercalation of gelatin takes place. One of the most salient features of the resulting bio-nanocomposites is the possibility to be processed as homogeneous thin films provided of good mechanical properties and transparency. The Young's modulus of gelatin-sepiolite bio-nanocomposites may increase by a factor of 2.5 with respect to neat gelatin. The incorporation of pH indicator dyes to the montmorillonite bio-nanocomposite films allows their application for optical pH sensing.
54 citations
TL;DR: In this paper, the authors describe the preparation of low-substituted hydroxypropyl (HP) starches and investigate their suitability for the development of flexible, highly transparent cast films.
Abstract: The present study describes the preparation of low-substituted hydroxypropyl (HP) starches and investigation of their suitability for the development of flexible, highly transparent cast films. Changes in molecular composition due to processing conditions were identified by determining molar mass distribution. Molecular characterisation was performed both by static light scattering (SLS) and size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS) detection. The weight-average molar mass, mean square radius of gyration, second virial coefficient, and molar mass distribution were determined. Rheological characterisation of concentrated aqueous solutions included a study of flow behaviour as a function of shear rate and oscillatory measurement of viscoelastic properties. Significant differences in rheological properties due to hydroxypropylation conditions were established. Mechanical testing was carried out by measuring tensile strength and elongation and determining the elastic modulus. The tensile strength of cast films based on hydroxypropyl starches was 40-50 MPa. Elongation values were dependent on the type of starch, use of plasticiser and storage conditions.
52 citations
TL;DR: In this article, the effect of magnetite content on the dielectric properties of the polymer film at different frequencies from 0.01 to 105 Hz was studied using an electrochemical impedance spectroscopy.
Abstract: Magnetite powders in nanometer size have been synthesized by the hydrothermal process. Various magnetic films of chitosan and the synthesized magnetite nanopowders containing different concentrations of the latter were prepared by ultrasonication route. The X-ray diffraction (XRD) studies and the transmission electron microscopy (TEM) images showed that the synthesized magnetite particles had 80 nm dimensions. The band gap of the composites was evaluated using the UV–visible Spectroscopy. The influence of magnetite content on the magnetic properties of the composite showed a decrease in the saturation magnetization with the decrease in the magnetic content. The effect of magnetite content on the dielectric properties of the polymer film at different frequencies from 0.01 to 105 Hz was studied using an electrochemical impedance spectroscopy. The possible mechanism for the observed electrical properties of the composite films was discussed.
52 citations