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Abstract
Coal-burning power stations generate huge amount of fine powder by-product, known as fly ash (FA). The storage and handling of FA are challenging tasks that affect the cost effectiveness of the relevant industry. Research on recycling and reuse of FA has lately become an interesting field of study in the emerging markets for green and eco-friendly manufacturing processes and products. The morphology of FA is spherical particles in different sizes ranges 2 - 100 µm. The sizes solely depend on the combustion of coal and post-cooling process of flue from furnace. These FA panicles were used to make polymer composites using polypropylene (PP) and Poly(vinyl alcohol) (PVA) as matrices.
Composites of FA reinforced non-polar isotactic semicrystalline PP were prepared by injection moulding at 210°C incorporating 20,45 and 60 wt% by weight of FA. Tensile tests were carried out at 25. 50 and 70°C. Modulus of elasticity of all composites at all temperatures was higher than that of the corresponding PP samples - the gain ranged 10- 60%. At 25°C, the composites suffered significant loss in strength. as much as 47%, whereas. at 50 and 70°C, there was up to 15 % gain in strength. Strain 10 failure of the composites samples ranged from as low as 6 % at 25°C to over 50 % at 70°C. In the study of thermal properties of composites, it was observed that the neat PP showed a mono- modal a crystalline phase, which changed into bimodal thermographs in the presence of FA, revealing partial trans-crystallization of α into β-phase, to a maximum 14 %.
In the study another types of biodegradable composite films, the polar polymer, polyvinyl alcohol (PVA) and FA - spanning 5, 10, 15, 20 and 25 wt% concentrations - were prepared by aqueous solution casting method. The tensile strengths of the composite films increased proportionally with addition of FA. The strength of the film enhanced by 193% with 20 wt%, FA whereas in the case of modified FA the value was raised to 420% higher strength due to formation of bridge like connection between FA and PVA compared to the neat PVA control. The Young's moduli of the composites also increased proportionally with FA addition to 212 % at 20wt% FA addition compared to the control. The percentage of strain at break exponentially decreased with addition of FA. The surface topography of the composite films ofPVA-MFA (modified-FA) was observed as 54% smoother compared to unmodified FA films based on the mean square roughness in AFM images.
Finally, Molecular Dynamic simulation (MD) attempts haw been taken to provide the insight in the computational prediction of physical adhesion properties of polymer with FA mullite material in co-relation with the whole study.