Influence of diisocyanate,glycidol and polyol molar ratios on the mechanical and thermal properties of glycidyl‐terminated biobased polyurethanes

A series of epoxy‐terminated polyurethanes (EPUs) were synthesized from castor oil, 4,4′‐methylenebis(cyclohexyl isocyanate) (H₁₂MDI) and 2,3‐epoxy‐1‐propanol (glycidol) by changing the molar ratio of H₁₂MDI to glycidol to polyol. Fourier transform infrared, ¹H NMR and solid‐state CP/MAS ¹³C NMR spectroscopic analyses revealed the presence of epoxy linkages within the polyurethane backbone. Thermogravimetric analysis showed that EPU4 with a polyol:diisocyanate:glycidol molar ratio of 1:6:6 exhibited an initial decomposition temperature of 128 °C, which was 26 °C higher than that of EPU1 (1:3:3 molar ratio). Differential scanning calorimetry showed an upward shift in the glass transition temperature with increasing molar ratio. Mechanical analysis demonstrated that the tensile modulus of EPU4 was 7.8 times greater than that of EPU1. The crosslinking densities of EPUs were determined using swelling studies which revealed a gradual increase in crosslinking density with increasing epoxy content within the polyurethane. The morphologies of cryo‐fractured surfaces of EPUs were determined through scanning electron microscopy to analyse the phase dispersion of epoxy and polyurethane. © 2017 Society of Chemical Industry     

Recent Development of Biobased Epoxy Resins: A Review

Currently, the utilization of renewable resources for sustainable technology is in the renown of consumer as well as industrial attention, especially, chemical industries because of their availability, low cost, credentials toward environmental issues such as lower ecotoxicity, CO₂ footprints, and inbuilt biodegradability. These natural properties are being taken advantage of in research and development, with vegetable oil-, furan-, lignin-, rosin-,vanillin-, and itaconic acid-derived biobased epoxy resin being used in various applications including paints, coatings, adhesives, and biomedicine. The present review mainly focuses on the utilization of natural resources for the synthesis of biobased epoxy and its curing agents.     

RGO/MgO hybrid nanocomposites with high specific capacitance

A scalable, cost effective synthesis of reduced graphene oxide (RGO)-magnesium oxide (MgO) hybrid nanocomposite (RGOMOHNC) is reported in the present work. The process involves an in-situ sonication method in aqueous medium at room temperature e.g., 30 °C. The as synthesized graphene oxide (GO) and RGOMOHNC powders are characterized by the XRD, FESEM, TEM, FTIR, RS and XPS techniques. The results indicate that in-situ growth of 20–30 nm MgO nanoparticles effectively increases the graphitic nature of the layered RGO microstructure. The experimentally measured cyclic voltammetry (CV) plots show that the specific capacitance of the RGOMOHNC powders is three orders of magnitude higher than that of the GO powders. A mechanism of RGOMOHNC formation has been proposed.     

Itaconic acid used as a versatile building block for the synthesis of renewable resource‐based resins and polyesters for future prospective: a review

Itaconic acid, a carbohydrate‐derived aliphatic dicarboxylic acid, is a potential chemical for the synthesis of renewable resource‐based resins and polyesters. Owing to environmental reasons, there is a gradual demand for renewable resources in the chemical industry. Conversely, as a rather underappreciated side effect of this growth, novel chemical building blocks are obtained, which are not commercially derived from petrochemical sources. In this respect, itaconic acid has attracted much attention and its trifunctional structure leads to the synthesis of novel polymeric materials. This review discusses the most relevant information for bio‐based resins and polyesters resulting from itaconic acid and distinctive properties for various commercial applications. © 2017 Society of Chemical Industry     

Defect Diagnosis Using a Current Ratio Based Quiescent Signal Analysis Model for Commercial Power Grids

Quiescent Signal Analysis (QSA) is a novel electrical-test-based diagnostic technique that uses I _DDQ measurements made at multiple chip supply pads as a means of locating shorting defects in the layout. The use of multiple supply pads reduces the adverse effects of leakage current by scaling the total leakage current over multiple measurements. In previous work, a resistance model for QSA was developed and demonstrated on a small circuit. In this paper, the weaknesses of the original QSA model are identified, in the context of a production power grid (PPG) and probe card model, and a new model is described. The new QSA algorithm is developed from the analysis of I _DDQ contour plots. A family of hyperbola curves is shown to be a good fit to the contour curves. The parameters to the hyperbola equations are derived with the help of inserted calibration transistors. Simulation experiments are used to demonstrate the prediction accuracy of the method on a PPG.     

A simple microemulsion based method for the synthesis of gold nanoparticles

The production of gold nanoparticles and nanoplates by enzymatically-synthesized lauroyl glucose, lauroyl fructose and lauroyl ascorbate is described. These emulsifiers formed oil-in-water microemulsions with toluene and the available reducing groups brought about a rapid reduction of chloroauric acid (HAuCl₄). Gold nanoparticles could thus be synthesized without the use of an additional reducing agent. Optical images, UV–visible spectroscopy, scanning electron microscopy, energy dispersive spectra (SEM–EDS) and X-ray diffraction (XRD) analysis revealed the presence of gold nanoparticles, which on further incubation aggregated into nanoplates. This paper thus describes a novel application of the enzymatically-synthesized esters.     

Generation and mesolytic dynamics of organoselenane and selenosilane radical ions: development of mechanistically interesting and synthetically useful chemistry

PET oxidation of PhSe-SePh and R-CH2-Se-R' generates an electrophilic selenium and carbocationic species, respectively. Similarly, one-electron reductive activations of R-CH2-Se-R' and R3-Si-SePh produces alkyl and alkyl silyl radicals, respectively. The possible structure of the reactive electrophilic selenium species is discussed and the fragmentation of -C-Se]*+ is found to be nucleophilic-assisted. These mechanistically interesting studies have been shown to be useful in initiating various synthetic reactions.