Utilization of Nanostructured Fly Ash in Polymer Matrix Composites

Abstract

Fly ash (FA) is a by-product generated during the combustion of pulverized coal in power generating thermal stations. In this study, a class-F FA was subjected to mechano-chemical activation by high energy ball milling. Mechano-chemical activation was carried out in presence of a surfactant and an inert liquid medium to obtain nanostuctured FA. The morphological, compositional, spectral and structural properties of the mechano-chemically activated FA (MCA-FA) were characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, dynamic laser scattering and Brunauer-Emmett-Teller surface area analysis. The fresh FA and MCA-FA were incorporated as fillers in ethylene-octene random copolymer and poly(vinyl alcohol) matrices. Morphological studies revealed that interfacial adhesion between the polymer and MCA-FA was good, which accounted for the improvement in mechanical properties of these composites. Thermal properties and flammability of ethylene-octene random copolymer and poly(vinyl alcohol) composites were enhanced on the addition of fresh FA and MCA-FA. The design of statistical analysis by Taguchi methodology was used to study the influence of milling parameters to obtain nanostructured FA. Ball milling parameters, such as ball-to-powder weight ratio, type and quantity of surfactant and type of medium were varied as guided by the Taguchi design. An orthogonal array and analysis of variance were employed to analyze the effect of milling parameters. According to the results obtained from analysis of variance, the factors ball-to-powder weight ratio and surfactant type emerged as the major contributing factors. Also, a fractal approach was used to characterize the lacunarity of the agglomerates in the MCA-FA. The MCA-FA was characterized by various techniques. Later, chitosan and poly(vinyl chloride) composites were prepared using fresh FA and MCA-FA. The key parameters for the enhancement of the properties of these composites and compatibility between MCA-FA and matrices were interfacial adhesion and morphology of these fillers.