Reduced graphene oxide (rGO) was synthesized from graphite flakes utilizing improved Hummers method via graphene oxide (GO) precursor. The oxidation of graphite and subsequent reduction of GO were ...confirmed by using FTIR, XRD, Raman spectroscopy and TEM techniques. The nanocomposite adhesives were developed using GO and rGO with different loading of 0–1.0 wt%. The adhesive strength was studied by conducting lap shear test and it was noticed that, Ep-0.5 GO adhesive exhibited the highest strength among all adhesive formulations and showed ∼50% increment than pristine epoxy. Impact strength evidenced noticeable enhancement with decrease in notch depth from 2.54 to 0.5 mm for all adhesive systems clearly indicating brittle to ductile transition due to the declining stress concentration area. The fracture analysis of impact samples and extent of fillers dispersion were visualized by SEM. SEM micrographs evidenced clear surface contrast of samples based on variable notch depth. The electrical resistivity in Ep-rGO systems showed 93% decrease with 1 wt% rGO loading, while thermal conductivity of Ep-0.5 GO revealed 211% increment as compared to pristine epoxy.
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•Synthesis of reduced graphene oxide (rGO) using improved Hummers method.•Superior mechanical properties for Ep-GO adhesives than their rGO counterparts.•Adhesive's impact strength increased with decreasing notch depth from 2.54 to 0.5 mm.•ρ of Ep-rGO systems was superior than Ep-GO systems, while contrary result for Tc.•Tg of all nanocomposite adhesives diminished with inclusion of nanomaterials.
Hydroxyapatite (HAp) is a member of the calcium apatite family that has been widely employed as an implant material in bone tissue regeneration (osteogenesis) and as a drug carrier in the drug ...delivery system. HAp exhibits excellent biocompatibility, high bioactivity, excellent osteoconduction, osteointegration, and osteoinductive properties. Emerging technology plays a vital role in exploring the various forms of hydroxyapatite for different regenerative purposes in vitro and in vivo. Nanostructured HAp can attach proteins and generate regulated apatite structures to promote the basic structure of bone and other tissues. This review summarizes hydroxyapatite extraction from natural sources including mammalian, marine, shell, and plant sources. Synthesis of HAp from synthetic precursor via different dry (solid-state and mechanochemical method) and wet processes (Sol-gel, hydrothermal, and chemical precipitation) has been described. Moreover, the effect of doping of various ions and compounding with natural and synthetic polymer and their application in tissue engineering has been discussed in detail. Composite biomaterials with HAp showed better cell adhesion and cell proliferation and in-vivo studies showed significant bone formation with hydroxyapatite composite materials. This review gives comprehensive insights into the development of HAp based material for tissue engineering.
Polymeric piezoelectric composites for energy harvesting applications are considered a significant research field which provides the convenience of mechanical flexibility, suitable voltage with ...sufficient power output, lower manufacturing cost, and rapid processing compared to ceramic‐based composites. This review focuses majorly on the basic theory and principles behind piezoelectric energy harvesting (PEH) devices, followed by specified materials used for the different devices. Different structural configurations associated with fabrication of PEH devices are discussed in detail along with their major advantages and drawbacks. Numerous classes of piezoelectric polymers such as polyvinylidene fluoride, polylactic acid, cellulose, polyamides, polyurea, polyurethanes, and their composites used for energy harvesting applications as a productive alternative of lead‐based piezo‐ceramics, are extensively addressed and explored. Additionally, current global and Indian scenarios associated with PEH devices, major challenges associated with them, and the future perspective of such devices are also reported in this review.
The versatility of different piezoelectric materials for energy harvesting applications is explored throughout this review while giving special attention to piezoelectric polymers and composites. It has been revealed that these materials could be a better alternative to piezo‐ceramics, in terms of mechanical flexibility, suitable voltage with sufficient power output, lower manufacturing cost, and rapid processing.
Polylactic acid (PLA)/poly (butylene succinate-co-adipate) (PBSA) based blend films at variable compositions and fixed weight percentage of Epoxy functionalized styrene acrylate (ESA) were prepared ...using a single step blending process, followed by blown film extrusion process. The morphological studies revealed proper interaction between polymers by the interaction of chain extender (ESA) subsequently improved the mechanical properties of the prepared blown films. Similarly, the blend films showed a decrease in oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) in the order of 60% and 14% as compared with VPLA film. The optical and antislip properties of the blend films also increased considerably. The thermal analysis of the blend films depicted marginal enhancement in the stability of PLA along with heterogeneous nucleation effect in PLA matrix due to the presence of ESA and PBSA.
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•The reactive blend films of PLA/PBS/ESA can be utilized in various packaging applications owing to its good mechanical, barrier and optical properties.•The film formation was accomplished using melt blending in a twin screw extruder followed by extrusion blown film process.•Several characterization techniques were employed to evaluate the potential of blown films pertaining to flexible packaging applications.
Polymer composites have been a material of choice for lightweight and durable applications in sectors ranging from automobile, packaging, structural components, and electronics to energy harvesting. ...Their versatility and ability to be tailored to application requirements have made them prospective alternatives for metal enclosures used in communication systems, power electronics, electric motors, and generators. The easy processing and high strength-to-weight ratio provide advantages over traditional materials that involve time- and-labor intensive processes. However, high thermal conductivity (TC) and electromagnetic interference (EMI) shielding are factors limiting their penetration into niche markets, and thus the development of alternatives with high TC and EMI shielding efficiency is critical. Thermally conductive polymer composites and EMI shielding effectiveness (SE) is a current issue in different applications including polymers providing light weight, corrosion resistance, and ease of processing as compared with metal. This paper focuses on improvements in the TC and shielding effectiveness of polymers by incorporating various fillers including carbon-based, mineral-based, and hybrid fillers. The paper reviews the current research worldwide regarding the enhancement of the TC and shielding effectiveness of polymer composites.
Ostrinia nubilalis
, also known as European Corn Borer (ECB), is a serious pest in Europe and North America, as well as in Central Asia and Northern Africa. It damages a variety of agricultural crops ...such as corn, oats, buckwheat, millet, and soybeans. causing annually at least one billion dollars in loss. The
Ostrinia nubilalis
pheromone-binding protein3 (OnubPBP3), preferentially expressed in the male moth antenna, has been implicated in the detection of the female-secreted pheromone blend during the mating process. Understanding the structure of and function of OnubPBP3, including the mechanism of pheromone binding and its release at the dendritic olfactory neuron (ORN), is essential if integrated pest management through sensory inhibition is to be achieved. We report here the backbone and side-chain resonance assignments of OnubPBP3 at pH 6.5 using various triple resonance NMR experiments on a
13
C,
15
N-labeled protein sample. The secondary structure of OnubPBP3 consists of six α-helices and an unstructured C-terminus based on backbone chemical shifts.
The comparative study of biodegradation of various blown films obtained from Poly (lactic) acid (PLA) has been studied via soil burial method. A total of 3-different types of films prepared from neat ...PLA and the reactive blends containing poly butylenes succinate-co-adipate (PBSA), and thermoplasticized starch (TPS); namely VPLA, PLA/PBSA, PLA/TPS respectively were the subjects of investigation. Several analytical techniques including weight loss method and analysis of mechanical properties were performed in each seven days interval until ninety days to elucidate the biodegradation in soil. The tensile modulus of VPLA and PLA/PBSA blown films were deteriorated to the tune of 60.32% and 71.28% respectively within 28 days, while PLA/TPS blown films recorded a significant reduction of 75.31% in the modulus value within 21 days of soil exposure compared to unexposed blown film samples. Similarly, blown films of PLA/TPS reported the highest rate of weight loss in the order of 40.06% in 90 days of soil burial with an estimated half-life of 103 days in soil environment compared to its counterparts. The depletion in both mechanical properties and weight of the film samples suggesting the occurrence of biodegradation in the real soil environment. Scanning electron microscopy (SEM) revealed the formation of coarse morphology for all three types of soil buried samples which trace of microbial action appeared on PLA/TPS films. Fourier transform infrared microscope (FTIR) showed the decrease in carbonyl index and variation in the intensities of carbonyl and hydroxyl peaks irrespective of the film samples after 90 days of soil exposure. Gel permeation chromatography (GPC) documented reduction in molecular weight and variation in polydispersity index (PDI) of post-exposed soil samples. The elemental analysis exhibited that the percentage of organic carbon and hydrogen content of all the films decreased while the oxygen percentage increased after soil burial due to the biodegradation of film specimens. Both Differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD) reported increase in crystallinity for soil exposed samples indicating the initiation of degradation kinetics preferably at the amorphous region of film composition. It has also been inferred that the biodegradation mechanism of VPLA and PLA/PBSA blown films predominantly driven by hydrolysis of ester bond. Contrastingly, the biodegradation kinetics in case of PLA/TPS film has been proceeded with microbial assimilation of TPS component which further thrived on hydrolysis of PLA component of the blown film system.
Graphic Abstract
In the current work, a candid approach has been reported to synthesize epoxy based electrically conductive adhesives (ECAs) using synergistic effect of polypyrrole (PPy) and reduced graphene oxide ...(rGO) filler mixture. Further, an in-depth study has been done to investigate the adhesive, impact and thermal conductive properties of the developed ECAs. The fabrication of ECAs was performed by varying the concentration of PPy from 5 to 10 wt% and the content of rGO from 0.5 to 1.0 wt%, respectively. FTIR and XRD studies unveiled effective interaction of PPy, rGO and PPy/rGO filler mixture with epoxy resin in the adhesive systems. The lap shear strength showed enhancement as PPy, rGO and PPy/rGO filler mixture were introduced into the epoxy resin. Other mechanical properties such as tensile and impact strength of epoxy resin was found to be decreasing with the addition of PPy particles, while the incorporation of rGO and PPy/rGO filler mixture showed contrary results. The volume conductivity was enhanced up to 2.33 × 10−09 S/m which is four-orders higher than that of E resin, when 5 PPy/0.5 rGO filler mixture were introduced. The thermal conductivity of E-5 PPy/1.0 rGO adhesive exhibited optimum value of 0.41 W/mK among all the adhesives. The enhancement of storage modulus and thermo-stability of epoxy adhesive with the addition of PPy/rGO filler mixture were confirmed by DMA and TGA techniques, respectively.
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•Lap shear strength of epoxy resin improved with PPy/rGO filler mixture.•Superior mechanical properties for E-PPy/rGO adhesives than E-PPy systems.•The optimum σv value for E-5 PPy/1.0 rGO adhesive among all adhesive systems.•Tc value of 0.41 W/mK for E-5 PPy/1.0 rGO system revealing synergism of PPy and rGO.•Tg increased to 116 °C with 0.5 wt% rGO inclusion into E-5 PPy adhesive.
The uncertain climatic changes-related issues in the recent times has led an apprehension for all automotive makers to develop innovative composite materials to reduce vehicle’s fuel consumption. ...Hence, this review article has given special attention toward the factors that motivated several automakers to undergo research on biocomposites as it plays an important role for biodegradability and sustainability across the globe. In particular, cellulose nanofibers-reinforced composites are the main research focus in the current scenario which can be applied for different automotive applications with numerous advantages and abundant accessibility. Polypropylene (PP) is the emerging polymer in the automotive industry, and many researchers are now mainly focusing their research on PP-based composites which can serve as a boon for different environmental problems faced by the current scenario as depicted by Figure 1. It also reported the recent advancement on the development of innovative composite materials by different automakers with regard to finding suitable actions for reduction of fuel consumption to the recommended confines.
Mutual funds remain the most favoured investment instrument in the extensive domain of finance due to healthy and blooming returns in its asset group. In order to take investment decision and gain ...maximum benefit from the highly evolving universal financial market with minimum risk, forecasting Net Asset Value (NAV) of mutual funds is an absolute necessity. This paper presents a NAV predictor model which is designed using the non-iterative Random Vector Functional Link Network (RVFLN). Further, the parameters of the model have been calibrated using a hybrid chaotic meta-heuristic technique that includes Differential Evolution (DE) algorithm and Flower Pollination Algorithm (FPA) in its learning stage. With the application of direct link between input and output nodes and randomized weights in RVFLN, an attempt has been made to enhance the prediction capability of the model by integrating the natural evolution features of DE and the pollination process of FPA along with chaos theory. Validation of efficacy of the proposed optimization technique (CDFPA) is accomplished using ten standard benchmark functions by assessing the convergence pattern against popular and recent meta-heuristics. The proposed RVFLN-CDFPA NAV forecasting model has been applied on real time data sets of three popular Indian mutual funds to predict one day ahead NAV. Also, this research presents a comparison analysis to look into the consequences of various activation functions and popular chaotic maps on the performance of the suggested model. The potential of the novel integrated model has finally been compared with other state-of-the-art approaches. The proposed model exhibits an improved performance over other RVFLN based predictor models like RVFLN-CHFPA, RVFLN-DFPA, RVFLN-FPA, RVFLN-DE, RVFLN-PSO, RVFLN-AO, RVFLN-RSA, RVFLN-AOA and RVFLN-SCA. Also, the novel integrated framework exhibits an improved performance of 61.37%, 72.41%, 71.16% and 69.61% in RMSE over RVFLN, ELM, CPNN-FPA and LPNN-CHFPA, respectively, for DSP fund. For UTI, an improvement of 64.54%, 83.71%, 83.30% and 55.70% in RMSE and for SBI, an improvement of 81.35%, 88.16%, 83.55% and 82.80% in RMSE are reported over RVFLN, ELM, CPNN-FPA and LPNN-CHFPA, respectively, which clearly reveal the competency of the proposed framework over other experimented models.
