High energy density capacitors are critically important in advanced electronic devices and power systems since they can reduce the weight, size and cost required to meet a desired application. ...Nanocomposites hold strong potential for increasing the performance of high power energy sources; however, the energy density of most nanocomposites is still low compared to commercial capacitors and neat polymers. Here, we develop a new synthesis method for the growth of high aspect ratio barium titanate nanowires (BaTiO3) nanowires (NWs) with high yield. High energy density nanocomposite capacitors are fabricated using surface‐functionalized high aspect ratio BaTiO3 NWs in a poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) matrix. At a 17.5% volume fraction, the nanocomposites show more than 45.3% increase in energy density above that of the pure P(VDF‐TrFE‐CFE) polymer (10.48 J/cc compared to 7.21 J/cc) at electric field 300 MV/m. This value is significant and exceeds those reported for the conventional polymer‐ceramic nanocomposites; it is also more than seven times larger than high performance commercial polypropylene capacitor (1.2 J/cc at 640 MV/m). In addition, our nanocomposite capacitor has a maximum power density as high as 1.2 MW/cc occurring only 1.52 μs after the start of discharge. The findings of this research could lead to enhanced interest in nanowires based nanocomposites due to their potential for achieving next generation energy storage devices.
High energy density nanocomposite capacitors are fabricated using surface‐functionalized high aspect ratio barium titanate (BaTiO3) nanowires in a poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) matrix. These nanocomposites show a high energy density of 10.48 J/cc and a maximum power density as high as 1.2 MW/cc, occurring only 1.52 μs after the start of discharge.
The design of nanocomposite capacitors poses certain challenges due to the reduced dielectric strength resulting from the integration of typically high dielectric fillers into the polymer. In prior ...efforts it was demonstrated that increasing of the filler could lead to energy‐storage densities up to 19.3% above the neat polymer. To further enhance the energy density, a novel strategy is developed to align nanowires in a thermoplastic matrix by uniaxial stretching assembly. It is demonstrated that the energy‐storage capability of the nanocomposite can be enhanced through the alignment of lead zirconate titanate (PZT) nanowires (NWs) in the direction of the applied electric field compared to randomly oriented samples. The maximum energy density of the nanocomposites is as high as 1.28 J cm−3 at a volume fraction of 40% PZT NWs (aspect ratio around 14) with axis of alignment in the direction of the electric field. The findings of this research could lead to broader interest due to development of the piezoceramic nanocomposites with enhanced dielectric properties for use in next‐generation energy‐storage and conversion devices.
Nanocomposites with aligned PZT nanowires are prepared by uniaxial strain assembly. It is demonstrated that the nanocomposites with nanowires aligned along the axis of the electric field have higher energy densities than samples with randomly dispersed nanowires. These results show that control of the orientation of the filler could be used to improve the energy density of nanocomposites.
Graphene consists of a monolayer of sp(2) bonded carbon atoms and has attracted considerable interest over recent years due to its extreme mechanical, electrical, and thermal properties. Graphene ...nanocomposites have naturally begun to be studied to capitalize upon these properties. A range of complex chemical and physical processing methods have been devised that achieve isolated graphene sheets that attempt to prevent aggregation. Here we demonstrate that the simple casting of a polymer solution containing dispersed graphene oxide, followed by thermal reduction, can produce well-isolated monolayer reduced-graphene oxide. The presence of single layer reduced-graphene oxide is quantitatively demonstrated through transmission electron microscopy and selected area electron diffraction studies and the reduction is verified by thermogravimetric, X-ray photoelectron spectroscopy, infrared spectrum, and electrical conductivity studies. These findings provide a simple, environmentally benign and commercially viable process to produce reduced-graphene oxide reinforced polymers without complex manufacturing, dispersion or reduction processes.
Composite materials can be enhanced by grafting a secondary material to a functional group on the surface of the reinforcing fibers to improve thermal, electrical or mechanical properties. Grafting ...secondary materials onto carbon fibers is often limited by the low reactivity of graphitic carbon and there is strong demand to create novel grafting methods with versatile functional groups. One desirable functional group is a carboxylic acid, which strongly interacts with many organic and inorganic materials. In this work, the surface of carbon fibers is functionalized by a reaction of naturally existing surface hydroxyl groups with isopropylidene malonate to graft terminal malonic esters, effectively creating a carboxyl functionalized surface. The reaction does not employ pre-oxidation to generate functional groups prior to grafting and is shown to preserve the tensile strength and morphology of the fiber. The surface functionalization is quantified by X-ray photoelectron spectroscopy, which shows that the relative surface coverage by carboxylic acid groups is increased from an initial 5.2% up to 9.2%. The effects of solvent, temperature, concentration and reaction time on the quantity of surface carboxylic acid groups are studied. This functionalization opens up new opportunities as a precursor reaction for further grafting reactions without sacrificing fiber strength.
One of the most important factors in the design of a fiber reinforced composite is the quality of the fiber/matrix interface. Recently carbon nanotubes and silicon carbide whiskers have been used to ...enhance the interfacial properties of composites; however, the high growth temperature degrade the fiber strength and significantly reduce the composite's in‐plane properties. Here, a novel method for enhancing the fiber/matrix interfacial strength that does not degrade the mechanical properties of the fiber is demonstrated. The composite is fabricated using low‐temperature solution‐based growth of ZnO nanowires on the surface of the reinforcing fiber. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113%, and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. This novel interface could also provide embedded functionality through the piezoelectric and semiconductive properties of ZnO.
A novel method for enhancing the fiber/matrix interfacial strength by growing ZnO nanowires on the surface of the reinforcing fiber is demonstrated. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113% and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. The composite is fabricated using low temperature solution based growth of ZnO nanowires on the surface of the reinforcing fiber.
Development of photocatalytic paint based on TiO2 nanoparticles and photopolymer resin for the degradation of organic pollutants in water under ultraviolet and sunlight irradiation.
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...•Development of photocatalytic paint based on TiO2 and photopolymer resin.•Applicability of the paint on various solid substrates.•Photocatalytic activity of the paint to degrade organic pollutants.•Efficient degradation of organic pollutants with high cyclic stability.•Generation of hydroxyl radicals under sunlight irradiation.
While the use of TiO2 nanoparticles in the form of slurry/suspension requires energy-intensive separation processes, its immobilization in solid support may open new opportunities in the area of sustainable water treatment technologies. In this study, a novel method for the development of photocatalytic paint based on TiO2 nanoparticles and acrylate-based photopolymer resin is reported. The paint (TiO2@polymer) was applied on substrates such as plastic petri dish and glass jar, which was polymerized/solidified by ultraviolet light irradiation. The painted petri dish and glass jar were used for the photocatalytic degradation of model organic pollutants viz. methyl orange (MO), methylene blue (MB), and indole in deionized water, simulated fresh drinking water, and tap water matrices. The photocatalytic degradation studies were performed under sunlight and UV-B light were used for. The sunlight-assisted photocatalytic degradation of MO and MB was found to be faster and more efficient than the UV-B light-assisted ones. Under UV-B light irradiation, it took 120 min to degrade about 80% of 6 ppm MB solution, whereas under sunlight irradiation it took 60 min to degrade about 90% of the same MB solution. The photocatalytic paint generated hydroxyl radical (·OH) under the UV-B and sunlight irradiation, which was studied by the terephthalic acid fluorescence tests. Further, the potential release of TiO2 during the exposure to UV irradiation was studied by single particle ICP-MS analysis.
Material extrusion 3D printing (ME3DP), based on fused deposition modeling (FDM) technology is currently the most widely available 3D printing platform. As is the case with other 3D printing methods, ...parts fabricated from ME3DP will exhibit physical property anisotropy where build direction has an effect on the mechanical properties of a given part. The work presented in this paper analyzes the effect of physical property-altering additives to acrylonitrile butadiene styrene (ABS) on mechanical property anisotropy. A total of six ABS-based polymer matrix composites and four polymer blends were created and evaluated. Tensile test specimens were printed in two build orientations and the differences in ultimate tensile strength and % elongation at break were compared between the two test sample versions. Fracture surface analysis was performed via scanning electron microscopy (SEM) which gave insight to the failure modes and rheology of the novel material systems as compared to specimens fabricated from the same ABS base resin. Here it was found that a ternary blend of ABS combined with styrene ethylene butadiene styrene (SEBS) and ultra high molecular weight polyethylene (UHMWPE) lowered the mechanical property anisotropy in terms of relative UTS to a difference of 22±2.07% as compared to 47±7.23% for samples printed from ABS. The work here demonstrates the mitigation of a problem associated with 3D printing as a whole through novel materials development and analyzes the effects of adding a wide variety of materials on the physical properties of a thermoplastic base resin.
The ability to tailor interfacial shear strength for a particular fiber and resin system is critical to the development of composite materials that perform optimally in specific applications. One ...approach to tailor the interface is to introduce a secondary phase between the fiber and matrix, which can act to functionally grade the material properties and enhance load transfer across the interface. This approach has been applied in the past using nanowires, nanotubes, and whiskers and was demonstrated to significantly enhance interface performance. Unfortunately, these processes lack control over the interphase morphology to allow design of the interface for optimal properties. Recently, ZnO nanowires grown on the surface of carbon fibers have demonstrated more than a 110% increase in interfacial strength
1. Unlike other treatments, this interfacial reinforcement allows precise morphology control. Here, we develop the parameters for the growth of nanowires with varying lengths and diameters and study the influence of the nanowire’s morphology on the interfacial shear strength. ZnO nanowire arrays are grown on carbon fibers, with nanowire diameters ranging from 50 to 200
nm and lengths up to 4
μm. The interfacial shear strength with varying nanowire dimensions is shown to increase by up to 228%, ranging from 45.72 to 154.64
MPa. Unlike existing whiskerization approaches, it is shown that the tensile strength of the ZnO nanowire coated fibers remains constant throughout all growth procedures. The development of an interphase offering control over the interface strength and toughness will provide a means to produce multifunctional composites with optimized performance for multiple applications.
Colon cancer (CC) is a common tumor that causes significant harm to human health. Bacteria play a vital role in cancer biology, particularly the biology of CC. Genes related to bacterial response ...were seldom used to construct prognosis models. We constructed a bacterial response-related risk model based on three Molecular Signatures Database gene sets to explore new markers for predicting CC prognosis.
The Cancer Genome Atlas (TCGA) colon adenocarcinoma samples were used as the training set, and Gene Expression Omnibus (GEO) databases were used as the test set. Differentially expressed bacterial response-related genes were identified for prognostic gene selection. Univariate Cox regression analysis, least absolute shrinkage and selection operator-penalized Cox regression analysis, and multivariate Cox regression analysis were performed to construct a prognostic risk model. The individual diagnostic effects of genes in the prognostic model were also evaluated. Moreover, differentially expressed long noncoding RNAs (lncRNAs) were identified. Finally, the expression of these genes was validated using quantitative polymerase chain reaction (qPCR) in cell lines and tissues.
A prognostic signature was constructed based on seven bacterial response genes: LGALS4, RORC, DDIT3, NSUN5, RBCK1, RGL2, and SERPINE1. Patients were assigned a risk score based on the prognostic model, and patients in the TCGA cohort with a high risk score had a poorer prognosis than those with a low risk score; a similar finding was observed in the GEO cohort. These seven prognostic model genes were also independent diagnostic factors. Finally, qPCR validated the differential expression of the seven model genes and two coexpressed lncRNAs (C6orf223 and SLC12A9-AS1) in 27 pairs of CC and normal tissues. Differential expression of LGALS4 and NSUN5 was also verified in cell lines (FHC, COLO320DM, SW480).
We created a seven-gene bacterial response-related gene signature that can accurately predict the outcomes of patients with CC. This model can provide valuable insights for personalized treatment.
The use of piezoceramic materials for structural sensing and actuation is a fairly well developed practice that has found use in a wide variety of applications. However, just as advanced composites ...offer numerous benefits over traditional engineering materials for structural design, actuators that utilize the active properties of piezoelectric fibers can improve upon many of the limitations encountered when using monolithic piezoceramic devices. Several new piezoelectric fiber composites have been developed, however almost all studies have implemented these devices such that they are surface-bonded patches used for sensing or actuation. This paper will introduce a novel active piezoelectric structural fiber that can be laid up in a composite material to perform sensing and actuation, in addition to providing load bearing functionality. The sensing and actuation aspects of this multifunctional material will allow composites to be designed with numerous embedded functions including, structural health monitoring, power generation, vibration sensing and control, damping, and shape control through anisotropic actuation. A one-dimensional micromechanics model of the piezoelectric fiber will be developed to characterize the feasibility of constructing structural composite lamina with high piezoelectric coupling. The theoretical model will be validated through finite element (FE) modeling in ABAQUS. The results will show that the electromechanical coupling of a fiber-reinforced polymer composite incorporating the active structural fiber (ASF) could be more than 70% of the active constituent.
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