Study of optical properties of potassium permanganate ($$\hbox {KMnO}_{4}$$) doped poly(methylmethacrylate) (PMMA) composite films

We have developed films of pure polymethylmethacrylate (PMMA) (0.5, 1, 2 and 5%) and potassium permanganate \((\hbox {KMnO}_{4})\)-doped PMMA composite films of thickness (\(\sim 100\, \upmu \hbox {m}\)) using the solution-cast technique. To identify the possible change that happen to the PMMA films due to doping, the optical properties were investigated for different concentrations of \(\hbox {KMnO}_{4}\) by recording the absorbance (A) and transmittance (\(T\%\)) spectra of these films using UV–Vis spectrophotometer in the wavelength range of 300–1100 nm. From the data obtained from the optical parameters viz. absorption coefficient (\(\alpha \)), extinction coefficient (\(\kappa \)), finesse coefficient (F), refractive index (\(\eta \)), real and imaginary parts of dielectric constant (\(\varepsilon _{\mathrm{r}}\) and \(\varepsilon _{\mathrm{i}})\) and optical conductivity (\(\sigma \)) were calculated for the prepared films. The indirect optical band gap for the pure and the doped-PMMA films were also estimated.     

Performance evaluation of an industrial solar dryer in Indian scenario: a techno-economic and environmental analysis

Clean Technologies and Environmental Policy - Food product drying is used to keep food products preserved for a long period and reduce post-harvest losses. Many industries dealing with food drying...     

Homogeneous and polymorphic transformations to ordered intermetallics in nanostructured Au–Cu multilayer thin films

Journal of Materials Science - Atomic arrangements in the nanostructured grains and interfaces of thermally evaporated Au/Cu multilayer thin films on polycrystalline Si substrate have been explored...     

Effect of polymer composition on performance properties of maleate-vinyl ether donor-acceptor UV-curable systems

The effect of unsaturated polyester backbone composition on the properties of donor-acceptor-UV-cured coatings was explored. The polyesters were designed with similar molecular weights and levels of unsaturation, but with otherwise widely varying backbone compositions. UV-curable coatings were formulated with stoichiometric levels of triethylenglycol divinyl ether and a photoinitiator. The resulting coatings had a broad range of properties, which were found to correlate with the properties and compositions of the polyester backbone polymers. A relatively flexible backbone resulted in lower glass transition temperatures (T_g). The polymer T_g was found to influence the conversion of double bonds achieved during UV curing. Reaction kinetics were evaluated for the coating systems and the results confirmed that the T_g of the systems influenced the double bond conversion. Thermal stability and König pendulum hardness were also found to vary with the backbone composition of the constituent polyester.     

A Multi-Functional Single-Stage Power Electronic Interface for Plug-In Electric Vehicles Application

This paper proposes a Zeta-derived non-isolated single-stage power electronic interface for on-board application of plug-in electric vehicles, which provides all modes (plug-in charging, propulsion, and regenerative braking) of vehicle operation. In addition, the proposed converter can charge the battery through universal input voltage range, i.e., 90–260 V due to buck/boost operations in plug-in charging mode. In propulsion and regenerative braking modes, the proposed converter operates as conventional boost and buck DC/DC converter, respectively. Compared to existing single-stage converters, the proposed converter has least components to those converters which have buck/boost operation in plug-in charging mode. A voltage/current stresses and loss analysis of the converter have been investigated for each mode of converter operation. Detailed simulation and experimental results are given to show the effectiveness of the proposed converter.     

Investigation of mechanical factor of soil reinforced with four types of fibers: An integrated experimental and extreme learning machine approach

ABSTRACT

This study investigates and compares mechanical factor (a dimensionless parameter and defined as the ratio of the compressive strength of fiber reinforced soil to that of unreinforced soil) for soils reinforced with four different fibers (three natural fibers and one synthetic fiber). An integrated methodology was utilized, including 351 laboratory experiments for obtaining data and Extreme Learning Machine (ELM) technique for developing functional relationships between mechanical factor and soil and fiber parameters. Soils reinforced with synthetic fiber (Polypropylene) and with natural fibers exhibited different characteristics when subjected to the same variation in soil parameters. This phenomenon can be attributed to the differences in surface morphology and water absorption capability of Polypropylene comparative to other natural fibers. Polypropylene–soil composite shows the maximum sensitivity to the soil moisture. It also shows the least sensitivity toward soil density and fiber content among all tested fiber–soil composites.     

Complete liquification time test coupled with solvent fractionation technique to detect adulteration of foreign fats in ghee

Complete liquification time (CLT) test (min:s) exploits the physical property of milk fat as the time required by solid fat to melt completely at a defined temperature. It has been used to detect adulteration of groundnut oil and goat body fat when added singly and in combination with ghee. The Complete liquification time test for samples containing a combination of adulterants was carried out before and after solvent fractionation. The results revealed that adulterants added individually could be detected at higher levels (15%, w/w, groundnut oil in cow ghee; and 10%, w/w, goat body fat in buffalo ghee), while fractionation reduced the detection limit to lowest level (10%, w/w) used in this study.     

Colloid‐in‐Liquid Crystal Gels that Respond to Biomolecular Interactions

This paper advances the design of stimuli‐responsive materials based on colloidal particles dispersed in liquid crystals (LCs). Specifically, thin films of colloid‐in‐liquid crystal (CLC) gels undergo easily visualized ordering transitions in response to reversible and irreversible (enzymatic) biomolecular interactions occurring at the aqueous interfaces of the gels. In particular, LC ordering transitions can propagate across the entire thickness of the gels. However, confinement of the LC to small domains with lateral sizes of ～10 μm does change the nature of the anchoring transitions, as compared to films of pure LC, due to the effects of confinement on the elastic energy stored in the LC. The effects of confinement are also observed to cause the response of individual domains of the LC within the CLC gel to vary significantly from one to another, indicating that manipulation of LC domain size and shape can provide the basis of a general and facile method to tune the response of these LC‐based physical gels to interfacial phenomena. Overall, the results presented in this paper establish that CLC gels offer a promising approach to the preparation of self‐supporting, LC‐based stimuli‐responsive materials.     

Prediction of Stress and Strain Based Forming Limit Diagram During Tube Hydroforming Process

Hydroforming process is most widely used in automotive industries. The current work involves the formability evaluation of DQ Steel and Al 5182 tubular blanks using the bulge test simulation done on PAM-STAMP 2G solver. The dependence of stress based forming limit diagrams are also evaluated in complex loading paths in case of hydro-forming as they are independent of strain paths.