Over the years, waste recycling has been a growing concern among many nations of the world, especially in developing countries. Expanded polystyrene (EPS) is used in electrical/electronic appliances as a shock absorber and constitutes a reasonable percentage of the entire plastic waste. There are three methods of recycling expanded polystyrene: mechanical, chemical, and thermal recycling; each of the above methods gives rise to different products that are used in different applications. Expanded polystyrene is used as a binder in emulsion paint as a replacement for conventional binders; as a component of asphalt used in road construction; as a component of wood plastic composites; as a blend with silica and in concrete to produce lightweight construction material. This article studied the various applications of recycled polystyrene waste from mechanical, chemical, and thermal methods of waste recycling.

This research produced textile pigment printing paste using expanded polystyrene (EPS) as a binder, sodium alginate as a thickener, and ultramarine pigment. The printing paste production was optimized through response surface methodology, using central composite design (CCD). The dynamic viscosity of the produced printing paste samples ranges from 5200 to 5550.50 cP (Centi Poise). The Fourier infrared transform (FTIR) spectroscopy revealed the functional groups present in the printing paste. The result of the thermogravimetric analysis (TGA) conducted shows a first step decomposition of 94.14% that occurred at the range of 30.96°C–127.75°C. Differential scanning calorimetry (DSC) showed an endothermic transition at 119.44°C due to the absorption of energy during the breaking of printing paste bonds. Textile characterization such as wash fastness, croak fastness, and light fastness was carried out to determine the suitability of the print paste on cotton and polyester fabrics. The results of the fastness tests range from 4 to 5 for wash fastness, 3 to 4/5 for croak fastness, and 4 to 6 for light fastness. The optimum values of the model variables are thickener (50%), binder (40%), and pigment (5%). The performance of the printing paste as revealed from the results is moderate and comparable with textile printing paste suitable for commercial application.