In the present study, the prime focus is to study the effect of a new solvent mixture on the formation of PVDF-co-HFP based nanocomposite membrane by solution casting method and their applicability ...to perform as a proton conducting membrane for fuel cell applications. A definite proportion two dipolar aprotic solvent mixture N-Methyl-2-pyrrolidone (NMP) and Acetonitrile (ACN) was used as the solvent mixture and it has been observed that the use of these solvents results in a porous structure with smaller micro domains within it, as evidenced from the FESEM micrographs. The mechanical resistance of the membranes also significantly improved with the change of solvent resulting in the formation of a ductile membrane. Incorporation of in-situ synthesized silanized silica nanoparticles into the polymer backbone following the sulfonation of the membranes using chlorosulfonic acid, also contributed in the improved physicochemical and the electrochemical properties with respect to higher water retention, better ion exchange capability (0.98 meq. g−1) and proton conductivities. Additionally, the silanized silica nanoparticles showed improved dispersibility within the polymer membrane thereby resulting in absorption of more sulfonic acid groups and shortened interchain separation distance which has been confirmed from XRD analysis. Thus, an interconnected proton conduction pathway which was formed, enhanced the proton conductivity to 0.113 S cm−1. Further, the barrier properties of the silica nanoparticles additionally suppressed the methanol crossover as compared with Nafion, while improving the membrane selectivity (3.65 × 104 S.scm−3).
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•A new solvent mixture has been employed to prepare the PVDF-co-HFP based membrane.•The proton conductivity of the membranes has been enhanced by 24.61% than Nafion 117 at 25 °C.•The membrane has a methanol permeability (3.02 × 10−6 cm2s−1) and improved membrane selectivity (3.65 × 104 S.scm−3).
Experimental and theoretical investigations on the heterojunction of silicon (Si) with chemically derived graphene have been presented. The stability study of graphene oxide and reduced graphene ...oxide (rGO) in aqueous medium were performed by visual observation and surface charge measurement. The detailed characterization by FT-IR, UV–Vis, and Raman spectroscopy exhibited the formation of rGO with a high optical band gap of 3.6eV. The atomic force microscopy analysis for rGO sample revealed the formation of flakes with thickness≈10nm. The rGO was spin-coated on the p-Si substrate for fabrication of a heterojunction device, with the structure of rGO/p-Si. In the fabricated device, incident light was transmitted through the thin rGO film to reach the junction interface, generating photoexciton, and thereby a photo-conversion efficiency of 0.02% was achieved. The theoretical simulation of rGO/p-Si heterojunction device using solar cell capacitance simulation 1D software showed the efficiency of 1.32%. Such large deviations in efficiency between experiment and theory have been discussed in details.
Polymer nanocomposite composed of polypyrrole, chitosan, and zinc oxide nanoparticles has been synthesized and it has been evaluated for various electrochemical aspects of the current electrochemical ...industry. The polypyrrole (PPy) was synthesized by the chemical oxidative polymerization reaction by employing ammonium persulfate as oxidizing agent. Composites of polypyrrole/chitosan (PPy/Chy) and polypyrrole/chitosan/ZnO (PCZ) composites were synthesized by the solution blending method. Detailed structural, morphological, thermal characterization of PPy, PPy/Chy, and PCZ were performed to characterize the specific features of the systems. The composites exhibit better thermal stability and high surface area and the addition of ZnO nanoparticle increase the crystallinity of the composite. Electrochemical characterization of the ITO electrodes modified with PPy, PPy/Chy, and PCZ were performed using cyclic voltammetry, electrochemical impedance spectroscopy, and amperometry techniques. The present study highlights the role of a bio‐compatible material with high surface area and conductive constituent for designing of various high performing electronic noninvasive sensors, biosensors, and so forth.
The current investigation deals with the effective utilization of plastics generated from electronic waste. In this study two different polymers: Poly (vinyl chloride) (PVC) collected from the data ...cables and Poly(methyl methacrylate) (PMMA) recovered from the liquid crystal display (LCD) panels used in computers were used to prepare the PVC/PMMA recycled blends using mechanical recycling technique at different compositions. The blends were characterized for various physico-mechanical, thermal, processability and morphological studies. Higher impact strength and elongation at break was observed for recycled blend with higher weight percentage of recycled PVC. The blend prepared at 70:30 wt ratio of recycled PVC (r-PVC): recycled PMMA (r-PMMA) in recycled blend exhibited better impact strength and elongation at break than the other blends. The thermal degradation of the recycled blend investigated using thermogravimetric analysis (TGA) suggested enhanced thermal stability of recycled blend than its individual recycled materials. The miscibility characteristics of the blends have been studied employing differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Both results show partial miscibility of r-PVC and r-PMMA in the recycled blend.
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•Examined mechanical recycling possibilities of PVC & PMMA recovered from WEEE.•Recycled blend of PVC and PMMA prepared using melt blending technique.•FTIR analysis shows the presence of molecular interaction in r-PVC/r-PMMA blends.•Physico-mechanical and thermal properties have been improved after preparing recycled blends.
The present study deals with the fabrication of nanocomposite membrane by incorporation of modified (3-aminopropyl)triethoxysilane treated silicon oxide (APTES-SiO2) within poly(vinylidene fluoride) ...(PVDF) matrix. Further, this nanocomposite membrane was treated with chlorosulfonic acid in order to incorporate the hydrophilic sulfonated (-SO3H) group within the membrane structure. The successful incorporation of nanoparticles within the host polymer structure as well as the sulfonation of the nanocomposite membranes were confirmed from FTIR, NMR and XPS studies respectively. The enhanced ion exchange capacity (0.6 meq g−1) and proton conductivity (9.4 × 10−2 S cm−1) indicate the potentiality of the membranes in fuel cell applications. Further, the greater conductivities of the membranes at high temperature indicates their suitability for performing at high temperature surroundings. The membranes displayed suppressed methanol crossover (50.21% lower as compared to Nafion) leading to more than one-fold higher membrane selectivity thus signifying a potential alternative to Nafion for fuel cell applications.
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•Successful incorporation of modified APTES-SiO2 within the host polymer PVDF.•Successful sulfonation of PVDF-APTES-SiO2 nanocomposite membrane.•Enhanced proton conductivity value of 9.4 × 10−2 S cm−1 is achieved at room temperature.•The methanol permeability of fabricated membranes, is 50.21% lower than corresponding Nafion.•The selectivity of fabricated membranes (2.72 × 104 S. scm−3) is 107% higher than that of Nafion 117.
In this paper, different types of carbon-based fillers such as graphite powder (GP), expanded graphite powder (EGP), expanded graphite flakes (EGF), silane treated expanded graphite flakes (EGS) and ...exfoliated graphene nanoplatelets (GNPs) were used at 40 wt% loading level inside epoxy resin for comparative thermal conductivity enhancement analysis. Disc-shaped epoxy adhesive composite samples were manufactured by hand layup and mechanical mixing technique. The thermal conductivity (k) of epoxy composites was measured according to ASTM E1530 standard at 60 °C by steady-state heat flow meter technique. It was enhanced to 0.96 (∼5 times), 2.50 (∼13 times) and 3.21 W/mK (∼17 times) for 40GP + 0Ep, 40EGF + 60Ep and 40EGS + 60Ep epoxy adhesive composites at 40 wt.% of filler loading level inside low conducting (k ∼ 0.194 W/mK) epoxy resin, respectively. From scanning electron microscopy, we observed the formation of the heat-conducting network through GP, EGF and EGS inside the epoxy matrix. The lap shear strength (LSS) of the epoxy adhesive joint was increased at 40 wt% of GP filler added epoxy adhesive but it decreased at 40 wt% EGF filler loading inside the epoxy resin. Introduction of EGF inside epoxy resin has influenced negative impact on TGA analysis (thermal stability) of epoxy adhesive than GP at initial stages of thermal degradation. This indicates the commercial use of these epoxy adhesives for heat dissipation application of electronic packaging industry.
A novel bioresin, epoxidized soybean oil was synthesized by in situ method and was characterized employing FTIR and NMR. The bioresin was blended with epoxy（DGEBA） at different ratios as reactive ...diluents for improved processibility and toughened nature. The composition with 20 wt% bioresin exhibited improved impact strength to the tune of 60% as compared to virgin epoxy. Fracture toughness parameters critical stress intensity factor（KIC） and critical strain energy release rate（GIC） were evaluated using single edge notch bending test and demonstrated superior enhancement in toughness. Dynamic mechanical, thermal, thermo mechanical and fracture morphological analyses have been studied for bio-based epoxy blends. Curing kinetics has been evaluated through DSC analysis to investigate the effect of bioresin on cross-linking reaction of neat epoxy with triethylenetetramine as curing agent.
The current study reports the preparation of polycarbonate (PC) nanocomposite using graphite flake (GF) and multi‐walled carbon nanotube (MWCNT) at varying weight percentages (10%, 20%, and 30%) by ...the melt mixing technique. The impact of filler on the properties of thermal conductivity (TC), electromagnetic interference shielding (EMI), electrical, and mechanical of the nanocomposite were studied. The improvement in the thermal conductivity value of ˃150% was achieved at a loading of 30% of graphite flake and 20% multiwalled carbon nanotubes. The morphology of the composite studied by field emission scanning electron microscope (FESEM), confirmed the dispersion of filler in the PC matrix. The electrical conductivity of both the optimized compositions achieved was in the order of 10−2 S/cm. Further, the EMI shielding of ∼35 and ∼32 dB was observed for graphite flake and MWCNT based composites, indicating the suitability of the developed system for various commercial applications.
In this article, the preparation of silicon carbide (SiC), carbon fiber (CF), and ethylene–propylene–diene monomer composite with different parts per hundred of SiC (phr) ratio (CF/SiC; 10/0, 0/10, ...10/10, 10/15, 10/20) and its effect on mechanical and thermal properties have been studied. After the incorporation of SiC up to 20 phr with a stable CF (10 phr), composites demonstrated higher tensile properties up to 12.09 MPa, elongation at break (725%), modulus (3.5 MPa), and hardness (79 Shore‐A) at composition (CF10SiC20 phr). Furthermore, the density of the composites has been achieved to a maximum value of 1.081 g/cm3 at composition (CF10SiC20 phr). The synthesized composite's functional group has been analyzed using Fourier‐transform infrared spectroscopy. The thermal stability of the composites increased with the inclusion of SiC up to 20 wt% while achieving the 520°C described by thermogravimetric analysis. After gamma irradiation analysis, the mechanical properties of the composites were slightly enhanced. Thermal conductivity of the composites has been maintained up to 0.21 W/mK at CF10SiC20 phr of the composites. The morphology of silicon carbide and carbon fiber was examined using scanning electron microscopy.
In the present study, the extent of jute and viscose fibre breakage during the extrusion process on the fracture toughness and the fatigue properties was investigated. The composite materials were ...manufactured using direct long fibre thermoplastic (D-LFT) extrusion, followed by compression moulding. The fracture toughness (KIC) and the fracture energy (GIC) of the PP–J30 composites were significantly improved (133% and 514%, respectively) with the addition of 10wt% viscose fibres, indicating hindered crack propagation. The addition of viscose fibres resulted in three times higher fatigue life compared with that of the unmodified jute composites. Further, with the addition of (2wt%) MAPP, the PP–J30–V10 resulted in a higher average viscose fibre length of 8.1mm, and the fracture toughness and fracture energy increased from 9.1 to 10.0MPam1/2 and 28.9 to 31.2kJ/m2, respectively. Similarly, the fatigue life increased 51% compared with the PP–J30–V10, thus demonstrating the increased work energy due to hindrance of the propagation of cracks.
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