Microstructural and Thermal Behaviour of Composite Material from Recycled Polyethylene Terephthalate and Fly Ash

Nowadays, the environmental impact of plastic waste is crucial, and in the energy industry, fly ash, a type of solid waste, has also prompted severe ecological and safety concerns. In this study, we synthesised composite material from two industrial wastes: recycled polyethylene terephthalate (rPET) as the matrix and fly ash as the filler. The effect of different fly ash loadings on the thermal behaviour and microstructure of the composite material using rPET were evaluated. Various loading amounts of fly ash, up to 68%, were added in the rPET mixtures, and composites were made using a single-threaded bar’s barrel extruder. The feeding zone, compression zone, and metering zone made up the three functional areas of the extruder machine with a single-flighted, stepped compression screw. The composite materials were subjected to DSC and SEM equipped with EDX spectroscopy tests to examine their thermal behaviour and microstructural development. It was found that the thermal behaviour of rPET improved with the addition of fly ash but degraded as the fly ash loading increased to 68%, as confirmed by the DSC study. The composites’ microstructural development revealed an even filler distribution within the polymer matrix. However, when the fly ash loading increased, voids and agglomeration accumulated, affecting the composites’ thermal behaviour.