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91.
Unsaturated polyester (UP)-toughened epoxy nanocomposites were prepared, and their effective mechanical and thermal properties were studied. Two types of organo-modified montmorillonite (OMMT) clays were used to prepare the nanocomposites. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis showed the formation of exfoliated silicate layers in the UP-toughened epoxy matrix. Mechanical tests revealed that nanocomposites (containing 1 wt% OMMT clay) showed an increase in tensile strength to 13.8%, flexural strength to 10%, and impact strength to 4% compared with an UP-toughened epoxy blend. The effect of different heating rates on the curing behavior of UP-toughened epoxy nanocomposites was investigated using non-isothermal differential scanning calorimetry. The data were interpreted using the Kissinger and Flynn–Wall–Ozawa models to find the curing reaction parameter. The water uptake behavior for nanocomposites increased with the addition of OMMTs. Scanning electron microscopy micrographs indicated morphological changes in the impact fractured samples of UP-toughened epoxy nanocomposites. 相似文献
92.
Rebecca Brannon Katharin Jensen Debasish Nayak 《Journal of the European Ceramic Society》2018,38(8):2971-2987
Even if a ceramic's homogenized properties (such as anisotropically evolving stiffness) truly can be predicted from complete knowledge of sub-continuum morphology (e.g., locations, sizes, shapes, orientations, and roughness of trillions of crystals, dislocations, impurities, pores, inclusions, and/or cracks), the necessary calculations are untenably hypervariate. Non-productive (almost derailing) debates over shortcomings of various first-principles ceramics theories are avoided in this work by discussing numerical coarsening in the context of a pedagogically appealing buckling foundation model that requires only sophomore-level understanding of springs, buckling hinges, dashpots, etc. Bypassing pre-requisites in constitutive modeling, this work aims to help students to understand the difference between damage and plasticity while also gaining experience in Monte-Carlo numerical optimization via scale-bridging that reduces memory and processor burden by orders of magnitude while accurately preserving aleatory (finite-sampling) perturbations that are crucial to accurately predict bifurcations, such as ceramic fragmentation. 相似文献
93.
Suchilipsa Das P. Ganga Raju Achary Nimai C. Nayak R.N.P. Choudhary 《Polymer Composites》2016,37(2):342-352
The dielectric relaxation behavior of different conducting carbon black‐filled ethylene‐octene copolymer (EOC) vulcanizates prepared by melt‐mixing method has been studied as a function of frequency (100 Hz–5 MHz) over a wide range of temperatures (25–100°C). The effect of filler loading and frequency on AC conductivity, dielectric permittivity, impedance, and dielectric loss tangent (tanδ) has been studied. The nature of variation of the dielectric permittivity with the filler loadings was explained on the basis of interfacial polarization of the filler in the polymer matrix. The effect of filler loading on the real and complex part of the impedance was explained by the relaxation dynamics of the polymer chains in the vicinity of the fillers. The effect of filler and temperature on dielectric loss tangent, dielectric permittivity, AC conductivity, and Nyquist plot was also reported. The bound rubber (BR) value increases with increase in filler loading suggesting the formation of strong interphase, which is correlated with dielectric loss. Thermal activation energy (Ea) was found to be decreasing with the temperature, which follows the Arrhenius relation: τb = τ0 exp(−Ea/KBT) where τb is the relaxation time for the bulk material. From the plot of lnτb versus inverse of absolute temperature (1/T), the activation energies (Ea) were found to be 0.37 and 0.44eV, respectively. The percolation threshold was observed with 40 phr carbon black loading. POLYM. COMPOS., 37:342–352, 2016. © 2014 Society of Plastics Engineers 相似文献
94.
Chinnathaypgal Veeresh Nayak Rangarasaiah Ramesh Motagondanahalli Desai Vijay Samanta Sudip Kumar 《SILICON》2019,11(1):175-185
Silicon - Metal injection moulding (MIM) is a near-net shape manufacturing technology for producing intricate parts, cost-effectively. MIM comprises combined techniques of plastic injection... 相似文献
95.
96.
Prasant Kumar Nayak 《Materials Letters》2010,64(11):1319-1321
Manganese dioxide is known to be an important electroactive material for supercapacitors. Generally, δ-MnO2 is subjected to electrochemical characterization studies in aqueous electrolytes of Na2SO4. It exhibits capacitance behaviour in the potential range between 0 and 1.0 V vs. SCE (saturated calomel electrode). In the present study, it is shown that δ-MnO2 exhibits capacitance behaviour in Sr(NO3)2 electrolytes also. The suitable potential range in this electrolyte is also found to be 0-1.0 V. Specific capacitance measured in Sr(NO3)2 electrolyte is 192 F g− 1. X-ray photoelectron spectroscopy data confirm that Sr2+ ions get inserted onto δ-MnO2 nanoparticles. 相似文献
97.
Voltammetric Response and Determination of an Anti-Inflammatory Drug at a Cationic Surfactant-Modified Glassy Carbon Electrode 下载免费PDF全文
Electrochemical oxidation of thiosalicylic acid in the presence of cationic surfactant, cetyl trimethylammonium bromide (CTAB), at a glassy carbon electrode was investigated. The electrochemical response of a modified sensor towards thiosalicylic acid determination was studied by the means of cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry (DPV). The liquid phase oxidation of thiosalicylic acid in the presence of CTAB leads to a notable enhancement in the peak current and a lowering of the peak potential. The electrochemical process was observed to be adsorption-controlled, irreversible and involves oxidation of one electron. Effects of anodic peak potential (E p), anodic peak current (I pa) and heterogeneous rate constant (k 0) were calculated. The linear response was obtained in the range of 1.0 µM–1.0 mM with a detection limit of 113 nM. 相似文献
98.
Prabhakara Rao Darapureddi Rati Ranjan Nayak 《Journal of surfactants and detergents》2016,19(6):1133-1142
Our present research describes the surface properties of three biobased anionic surfactant synthesized from vinylguaiacol and 11-bromo undecanoic acid. To further improve its hydrophobicity and bioavailability, amino acid head group incorporation was carried out. All these synthesized compounds were thoroughly characterized using NMR and mass spectroscopy. The performance properties such as foaming, wetting, emulsification value and calcium tolerance were evaluated. The studied surfactants possess excellent emulsion stability and moderate calcium tolerance as compared to commercially available surfactant sodium lauryl sulfate (SLS). The micelle formation and the thermodynamics involved at the air–water interface were estimated from surface tension measurements. These surfactants showed a higher tendency towards adsorption at the air–water interface than micellization. Dynamic light scattering and steady state fluorescence anisotropy study were carried out to shed light on the bulk micellization properties of the synthesized surfactant. Along with spherical micelles of <5 nm size, larger aggregates (35–84 nm) were observed with higher anisotropy values. FESEM images further confirmed the larger spherical micelles formed by these surfactants. The surfactants formed chiral aggregates above the critical micelle concentration as indicated by circular dichroism spectra. These surfactants may be suitable candidates for additives to detergents to improve their calcium tolerance especially in the case of hard water. Furthermore, a low foaming ability along with high emulsion stability may find these surfactants to be better replacement of the conventional surfactant used as emulsifiers in many industrial applications. 相似文献
99.
In this research program, chitosan film was prepared by blending chitosan with Cloisite 30 B at different concentrations 0 wt %, 1 wt %, and 2.5 wt %. The blends were characterized by Fourier transmission infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X‐ray diffraction (XRD) analysis. From the FTIR spectra the various groups present in chitosan/C 30 B blend were monitored. The homogeneity, morphology, and crystallinity of the blends were ascertained from SEM and XRD data, respectively. The most suitable form of blend was taken and used as a carrier for the controlled release of ofloxacin. The swelling studies have been carried out at different drug loading. Drug release kinetics was analyzed by plotting the cumulative release data versus time by fitting to an exponential equation which indicated the occurrence of non‐Fickian type of kinetics. The drug release was investigated at different pH medium and it was found that the drug release depends upon the pH medium as well as the nature of matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
100.
Myofibrillar Protein Solubility of Model Beef Batters as Affected by Low Levels of Calcium, Magnesium and Zinc Chloride 总被引:1,自引:0,他引:1
Preblended composites of semimembranosus and adductor muscles were stored 12h at 4°C with 2.0% NaCl, 0 or 0.05% CaCl2, MgCl2, or ZnCl2 and 0 or 0.4% sodium tripolyphosphate (STPP). Model systems were formulated to contain 30% fat (high fat; HF) or 10% fat (low fat; LF). Divalent salts lowered extract pH and ZnCl2 elicited the greatest reduction. At both fat levels, CaCl2 increased and ZnCl2 decreased protein solubility, compared to the control (p<0.05). Myosin was not detected in ZnCl2-treated HF and LF batters without STPP and in the presence of STPP, MgCl2 and ZnCl2 increased myosin concentration at both fat levels (p<0.05). Zinc chloride increased actin concentration in HF batters; whereas, MgCl2 decreased soluble actin in LF batters (p<0.05). Magnesium chloride (0.05%) increased soluble proteins in LF batters containing 0.4% STPP by increasing myosin extractability. 相似文献