Blends of cardanol-based epoxidized novolac resin and CTBN for application in surface coating: a study on thermal,mechanical, chemical,and morphological characteristics

Blend samples of cardanol-based epoxidized novolac resin and different weight percentages of carboxyl-terminated butadiene acrylonitrile (CTBN) were developed and cured with stoichiometric amounts of aliphatic amine. The formation of various products during the curing of blend samples has been studied by Fourier-transform infrared spectroscopy. The dynamic differential scanning calorimeter scans showed that the pure epoxies and their blend samples with CTBN cured in the temperature range of 100–150°C. The blend sample containing 15 wt% CTBN showed the least cure time (at 120°C) among all other blend samples. Upon evaluation, it was found that blend samples exhibit better properties compared to pure epoxy resin in terms of increase in impact strength and elongation-at-break of the casting and gloss, scratch hardness, adhesion, and flexibility of the film. The improvement in these properties indicates that the rubber modified resin would be more durable than the epoxy based on cardanol. Chemical and morphological properties of the formulated resins were also determined. The thermal stability of the blend samples containing 15 wt% CTBN in epoxy resin was the highest among all other prepared systems. The blend morphology, studied by scanning electron microscope, showed the presence of precipitated discrete rubber particles, which dispersed throughout the epoxy matrix—i.e., they revealed the presence of two-phase morphological features.     

Earthworm coelomocytes as nanoscavenger of ZnO NPs

Earthworms can ‘biotransform’ or ‘biodegrade’ chemical contaminants, rendering them harmless in their bodies, and can bioaccumulate them in their tissues. They ‘absorb’ the dissolved chemicals through their moist ‘body wall’ due to the interstitial water and also ingest by ‘mouth’ while soil passes through the gut. Since the advent of the nanotechnology era, the environmental sink has been continuously receiving engineered nanomaterials as well as their derivatives. Our current understanding of the potential impact of nanomaterials and their natural scavenger is limited. In the present investigation, we studied the cellular uptake of ZnO nanoparticles (NPs) by coelomocytes especially by chloragocytes of Eisenia fetida and their role as nanoscavenger. Results from exposure to 100- and 50-nm ZnO NPs indicate that coelomocytes of the earthworm E. fetida show no significant DNA damage at a dose lower than 3 mg/l and have the potential ability to uptake ZnO NPs from the soil ecosystem and transform them into microparticles.     

Synergistic effect of some antiscalants as corrosion inhibitor for industrial cooling water system

In order to study synergistic effect, various combinations of antiscalants 1-hydroxyethane-1,1-diphosphonic acid (HEDP), sodium hexametaphosphate (SHMP), sodium tripolyphosphate (STPP), and trisodium phosphate (TSP), were investigated as corrosion inhibitors for carbon steel. Corrosion rate and percentage inhibition efficiency of various combinations of antiscalants as corrosion inhibitors (20/80, 40/60, 60/40, 50/50, 80/20, and 100 ppm of different combinations of HEDP, SHMP, STPP, and TSP) in synthetic cooling water VI (692 ppm of Cl⁻ ions) was determined by weight loss, electrochemical polarization technique, and metallurgical microscopy technique. It was observed that a 50/50 ppm combination of HEDP and SHMP gave 98% corrosion inhibition efficiency and maximum synergistic effect. The percentage inhibition efficiency of HEDP when mixed with other antiscalants as corrosion inhibitors at 50/50 ppm concentration was found in the following order HEDP/SHMP > HEDP/STPP > HEDP/TSP. The synergistic effect of HEDP/SHMP combination is due to intermolecular hydrogen bonding between the molecules of HEDP and SHMP, which results in the adsorption of uniform multilayered two-dimensional film of –HEDP–SHMP– molecules on carbon steel surface.     

Selectivity engineering in isopropylation of mesitylene with isopropyl alcohol over cesium substituted heteropolyacid supported on K-10 clay

Alkylation of aromatics catalyzed by solid acids constitutes a class of reactions of both academic and industrial importance. Among alkylation reactions, isopropylation of aromatic compounds has attracted considerable attention. Use of propylene as alkylating agent at very high temperatures leads to coke formation which results in deactivation of the catalyst. The use of isopropanol (IPA) as an alkylating agent is attractive when propylene is not readily available. In situ dehydration of IPA leads to prolonged activity since water of reaction suppresses coke formation. Further, IPA dehydration also generates diisopropyl ether which itself is an excellent alkylating agent. Alkylation of mesitylene with propylene or IPA results in the formation of 2-isopropyl-mesitylene (2-IPMT), which is almost extensively used as a precursor in a number of industrial chemicals. This work covers the evaluation of clay-supported heteropolyacids and sulfated zirconia. A variety of solid acid catalysts such as K-10 clay, sulfated zirconia, Filtrol-24, 20% w/w dodecatungstophosphoric acid (H₃PW₁₂O₄₀, DTP) supported on K-10 montmorillonite clay and 20% w/w cesium substituted dodecatungstophosphoric acid (Cs_2.5H_0.5PW₁₂O₄₀, Cs-DTP) supported on K-10 montmorillonite clay were investigated for the liquid phase isopropylation of mesitylene to 2-IPMT using IPA at much milder conditions vis-à-vis other catalysts reported so far. 20% w/w Cs-DTP/K-10 clay was found to be the best catalyst which gives 98% conversion of limiting component, IPA and 98% selectivity towards the desired product, 2-IPMT after 2 h of total reaction time. This catalyst could be reused without any further chemical treatment, eliminating the effluent disposal problems. The reaction was carried out without using any solvent and the process subscribes to the principles of green chemistry. The catalytic activity is in the following order: 20% w/w Cs-DTP/K-10 clay (most active) > 20% w/w DTP/K-10 clay > Filtrol-24 > Sulfated zirconia > K-10 clay (least active). The effect of various operating parameters and catalyst reusability were also systematically investigated. A mathematical model was proposed to probe into the intricate reaction kinetics and mechanism consistent with the experimental results. The reaction is free from any external mass transfer as well as intraparticle diffusion limitations and is intrinsically kinetically controlled. An overall second order kinetic equation was used to fit the experimental data, under the assumption that all the species are weakly adsorbed on the catalytic sites.     

Effect of Growth Temperature on Bamboo-shaped Carbon–Nitrogen (C–N) Nanotubes Synthesized Using Ferrocene Acetonitrile Precursor

This investigation deals with the effect of growth temperature on the microstructure, nitrogen content, and crystallinity of C–N nanotubes. The X-ray photoelectron spectroscopic (XPS) study reveals that the atomic percentage of nitrogen content in nanotubes decreases with an increase in growth temperature. Transmission electron microscopic investigations indicate that the bamboo compartment distance increases with an increase in growth temperature. The diameter of the nanotubes also increases with increasing growth temperature. Raman modes sharpen while the normalized intensity of the defect mode decreases almost linearly with increasing growth temperature. These changes are attributed to the reduction of defect concentration due to an increase in crystal planar domain sizes in graphite sheets with increasing temperature. Both XPS and Raman spectral observations indicate that the C–N nanotubes grown at lower temperatures possess higher degree of disorder and higher N incorporation.     

Aesthetical design of a car profile: a Kano model-based hybrid approach

An amicable aesthetical design of a product is prudent for its wide acceptability and viability. Selection of shape parameters with customer satisfaction is critical in aesthetical design and a challenging task for designers. In the present work, the authors proposed a sequential approach to design a car profile with aesthetical aspects. The methodology is based on Kano model that provides a framework for incorporation of customer satisfaction with the design requirements. Further, Taguchi's robust design approach has been used to find the optimum level of the parameter to achieve initial design estimates and thereafter, response surface method (RSM) is applied to refine the optimum values, precisely. The methodology has been illustrated with a case study.     

Attenuation of ultrasonic waves in V, Nb and Ta at low temperatures

Variation of ultrasonic attenuation and velocities with temperature have been evaluated in the temperature range 5-50 K due to electron-phonon interaction mechanism in transition metals vanadium, niobium and tantalum for longitudinal and shear waves. For this evaluation, we have also computed the second order elastic constants using Morse potential. Behaviour of acoustical phonons in these bcc metals is different from other normal metals, intermetallics, semimetallics and alloys. Some characteristic features of these materials connected to ultrasonic parameters are discussed.     

Amperometric determination of tyramine in sauce and beer by epoxy resin biocomposite membrane bound tyramine oxidase

A method is described for construction of an amperometric biosensor for specific determination of tyramine, using black gram tyramine oxidase immobilized covalently on an epoxy resin membrane. The biosensor had optimum response within 10 s at pH 8.5 and 35 °C. A linear relationship was observed between tyramine concentrations and current (mA) in the range of 0.24 to 3.47 mg/dL. The biosensor was employed for determination of tyramine in beer and sauce. The detection limit of sensor was 0.24 mg/dL. The mean analytical recovery of added tyramine (0.5 and 1.0 mg/dL) was 97.3 ± 2.3 and 95.9 ± 3.4%. Within and between batch coefficient of variation were 5.1 and 5.34%, respectively. Enzyme electrode showed 35% loss in its initial activity after its regular use over a period of 2 months. The biosensor has the advantage that it does not suffer from leaching of enzyme and measures tyramine specifically.     

Isatin compounds as corrosion inhibitors for N80 steel in 15% HCl

The inhibition effect of two synthesized isatin compounds namely 1-morpholinomethyl-3-(1-N-dithiooxamide)iminoisatin [MMTOI] and 1-diphenylaminomethyl-3-(1-N-dithiooxamide)iminoisatin [PAMTOI] on the corrosion inhibition of N80 steel in 15% HCl solution was studied by polarization, EIS and weight loss measurements. It was found that both the inhibitors were effective and their inhibition efficiency was significantly increased with increasing concentration. Polarization curves revealed that the used inhibitors represent mixed-type inhibitors. Adsorption of these inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance, and was found also to obey Langmuir isotherm.