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.
Citations
More filters
Journal Article•
TL;DR: In this article, Boron nitride nanotubes (BNNT)/polyvinyl alcohol (PVA) composite fibers were fabricated via electrospinning so that all BNNTs became aligned in the fiber casting direction.
Abstract: Boron nitride nanotube (BNNT)/polyvinyl alcohol (PVA) composite fibers (<5 vol % BNNTs) were fabricated via electrospinning so that all BNNTs became aligned in the fiber casting direction. A several-fibers-thick ensemble of parallel-arranged contacting fibers made a single polymer sheet. Numerous sheets were then stacked in different ways with respect to the BNNT orientation (all fibers in adjacent sheets were either parallel or alternately rotated 90°) to make multilayer films that were finally hot-pressed. Various BNNT textures were reflected by the corresponding differences in the measured thermal conductivities of the resultant films due to anisotropy of thermal transport in the nanotubes. The highest values (0.54 W/mK) were obtained along the long axes of aligned BNNTs. Somewhat lower values (0.38 W/mK) were documented in films with alternately stacked fibers/tubes. The theoretical thermal conductivity values were estimated using the Nielsen’s model. These show good match with the experimental data. ...
162 citations
TL;DR: In this paper, the potential and market stability of gelatin has been discussed and its recent studies are summarised in this paper, focusing on assessing the general utilities of the various sources of collagen as gelatin derivatives.
120 citations
TL;DR: In this article, the authors summarized the recent progress in polymer electrolytes for flexible ZIBs, especially hydrogel electrolytes, including their synthesis and characterization, and provided an insight from lab research to commercialization, relevant challenges, device configurations, and life cycle analysis.
Abstract: Owing to the development of aqueous rechargeable zinc-ion batteries (ZIBs), flexible ZIBs are deemed as potential candidates to power wearable electronics. ZIBs with solid-state polymer electrolytes can not only maintain additional load-bearing properties, but exhibit enhanced electrochemical properties by preventing dendrite formation and inhibiting cathode dissolution. Substantial efforts have been applied to polymer electrolytes by developing solid polymer electrolytes, hydrogel polymer electrolytes, and hybrid polymer electrolytes; however, the research of polymer electrolytes for ZIBs is still immature. Herein, the recent progress in polymer electrolytes is summarized by category for flexible ZIBs, especially hydrogel electrolytes, including their synthesis and characterization. Aiming to provide an insight from lab research to commercialization, the relevant challenges, device configurations, and life cycle analysis are consolidated. As flexible batteries, the majority of polymer electrolytes exploited so far only emphasizes the electrochemical performance but the mechanical behavior and interactions with the electrode materials have hardly been considered. Hence, strategies of combining softness and strength and the integration with electrodes are discussed for flexible ZIBs. A ranking index, combining both electrochemical and mechanical properties, is introduced. Future research directions are also covered to guide research toward the commercialization of flexible ZIBs.
119 citations
TL;DR: A systematic review methodology based on the application of this novel technology in the field of drug delivery along with the manufacturing of polypills with varied release profiles and geometries is carried out.
72 citations
References
More filters
TL;DR: In this paper, small-diameter vascular grafts made of PCL nanofibers were compared with expanded polytetrafluoroethylene (ePTFE) grafts.
Abstract: Background—Long-term patency of conventional synthetic grafts is unsatisfactory below a 6-mm internal diameter. Poly(e-caprolactone) (PCL) is a promising biodegradable polymer with a longer degradation time. We aimed to evaluate in vivo healing and degradation characteristics of small-diameter vascular grafts made of PCL nanofibers compared with expanded polytetrafluoroethylene (ePTFE) grafts. Methods and Results—We prepared 2-mm–internal diameter grafts by electrospinning using PCL (Mn=80 000 g/mol). Either PCL (n=15) or ePTFE (n=15) grafts were implanted into 30 rats. Rats were followed up for 24 weeks. At the conclusion of the follow-up period, patency and structural integrity were evaluated by digital subtraction angiography. The abdominal aorta, including the graft, was harvested and investigated under light microscopy. Endothelial coverage, neointima formation, and transmural cellular ingrowth were measured by computed histomorphometry. All animals survived until the end of follow-up, and all grafts...
307 citations
TL;DR: A procedure for preparing individualized chitin nanofibers 3-4 nm in cross-sectional width and at least a few microns in length was developed and the original crystal structure of beta-chitin is maintained, although crystallinity index decreases from 0.51 to 0.37 as a result of the nanofiber conversion.
304 citations
TL;DR: In this article, the effect of polylactic acid (PLA) and polycaprolactone (PCL) resins on the brittle behavior of injection moldings was investigated.
Abstract: The improvement of the brittle behavior of Polylactic acid (PLA) resin was studied by blending it with Polycaprolactone (PCL) resin. These materials were fabricated into the compressed films and injection moldings. The values of tensile modulus and strength were appropriate, judging from the rule of mixtures. However, the ultimate tensile strain was very small. Dicumyl peroxide (DCP) was added to this blend system to improve its ultimate tensile strain. It was found that the value of ultimate tensile strain peaked at low DCP concentration. The samples at low DCP contents show yield point and ductile behavior under tensile test. The impact strength of the optimum composition was 2.5 times superior to neat PLA, and ductile behavior such as plastic deformation was observed at its fracture surface. It was found that the carbonyl groups of the blend material with DCP were altered by using FTIR spectroscopy. Dynamic mechanical analysis data revealed the dual phase nature of PLA/PCL blend albeit with good interfacial adhesion, and the DCP enhanced the viscous property in PCL phase, which agreed with tensile ductility and impact strength. The mechanical properties of this blend are comparable to those of general purpose HIPS and ABS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1816–1825, 2006
297 citations
TL;DR: In this article, the authors measured the gas permeability of adhesives of organically modified montmorillonite (OM) and polyurethane (PU) composites to oxygen and water vapor.
Abstract: Adhesive nanocomposites of organically modified montmorillonite (OM) and polyurethane have been synthesized and their permeability to oxygen and water vapor has been measured. The gas permeation through the composites was correlated to the volume fraction of the impermeable inorganic part of the OM. The incorporation of small volume fractions of the platelike nanoparticles in the polymer matrix decreased the gas transmission rate, when the interface between the two heterogeneous phases was properly designed. The oxygen transmission rate decayed asymptotically with increasing aluminosilicate volume fraction and a 30% reduction was achieved at 3 vol %, when the clay was coated with bis(2-hydroxyethyl) hydrogenated tallow ammonium or alkylbenzyldimethylammonium ions. In contrast, coating the clay surface with dimethyl dihydrogenated tallow ammonium ions leads to an increase in the gas transmission rate with augmenting inorganic fraction. This was attributed to a probable change in morphology resulting from phase separation at the interface between the apolar pure hydrocarbon clay coating and the relatively polar PU. The water vapor permeation through the PU nanocomposites was more strongly reduced than oxygen and a 50% reduction was observed at 3 vol % silicate fraction. This was attributed to stronger interactions and hydrogen bonding of the water molecules with the PU matrix as well as to their clustering. Differences in the hydrophobicity of the clay coating influenced the water transmission rate. No spectroscopic evidence could be obtained for a reaction between the hydroxyl groups of the clay organic coating and the isocyanate groups of the prepolymer. A mixed morphology, that is, exfoliated layers and intercalated particles was observed in all composites. WAXRD and TEM gave a qualitative picture of the microstructure of the nanocomposites but no conclusive information. Some of the problems to be solved before a correlation between the nanocomposite properties and their microstructure can be established have been outlined.
293 citations
Journal Article•
TL;DR: A series of blends of the biodegradable polymers poly(D,L-lactic acid) and poly( epsilon -caprolactone) were prepared by varying mass fraction across the range of compositions.
Abstract: A series of blends of the biodegradable polymers poly(D,L-lactic acid) and poly( epsilon -caprolactone) were prepared by varying mass fraction across the range of compositions. Tensile testing was performed at room temperature using an extensometer and the elastic modulus was calculated for each blend. The blends were also tested to failure, and the strain-at-failure and yield stress recorded. While the blend has been shown to have a lower critical solution temperature, the mechanical properties were insensitive to the annealing conditions. Scanning electron microscopy was used to characterize the blend microstructure and poor adhesion was observed at the interface between blend components. Differential scanning calorimetry was performed but the results were somewhat variable, indicating this blend may have complex phase behavior that depends sensitively on the method of preparation. However, nuclear magnetic resonance data indicate the two components are phase separated. A percolation model is used to explain the observed mechanical data and the results are consistent with the predictions of the Kerner-Uemura-Takayangi model. The results of these experiments demonstrate the utility of polymer blending in tuning material properties.
292 citations