No abstract

In this experiment, we have attempted to dope Cr into ZnO nanostructure as a function of dopant concentration using sol-gel method, followed by controlled thermal annealing with some success. We have also examined the samples thus prepared with scanning electron microscopy (SEM), X-ray powder diffraction (XRD), near edge X-ray absorption fine structure (NEXAFS), both theoretical and experimental, and magnetic measurements. We found that low concentration of Cr can indeed be doped in ZnO and is substitutional, occupying the tetrahedral site. However, upon increasing dopant concentration and annealing temperature, a secondary phase with Cr occupying an octahedral site precipitates out, which was evident from SEM, XRD, and NEXAFS. Ferromagnetism at room temperature was not observed in any samples, although at low Cr concentration and 400 °C processing temperature, antiferromagnetism can be seen; however, at higher concentrations or processing temperatures, the samples show only paramagnetism.

Biodegradable plastic composites designed with various natural and biobased material can potentially satisfy biodegradability specifications as per ASTM, CEN, ISO and OECD guidelines. A laboratory scale simulated aerobic composting facility (as per ASTM D 5338) was designed and utilized to determine and evaluate the extent of degradation of various components of compostable plastic composites. The materials of natural origin components like starch, microcrystalline cellulose, cellulose fibre, wheat straw, soy straw, distiller's dried grains with solubles (DDGS) and soy meal demonstrated ready degradability with conversion of 60% of the organic carbon to carbon dioxide. The individual polymers polylactic acid (PLA) and polycaprolactone (PCL) showed inherent degradability of 60% of the organic carbon to carbon dioxide within 180 days. The composites of polymers PLA with wheat straw and soy straw and PCL with DDGS and soy meal showed inherent degradability of 60% of the organic carbon to carbon dioxide within 180 days. Enhanced compostability of plastic is observed with inclusion of natural, ready degradable components in the composite in comparison to the individual polymer.