Reduction of polystyrene/polyurethane plastic wastes from the environment into binders for water-resistant emulsion paints

Sunday A Osemeahon; Ayodele Akinterinwa; Esther Fasina; Fartisincha P Andrew; Muhammed H Shagal; Semiu A Kareem; Usaku Reuben; Patience U Onyebuchi; Olubukola R Adelagun; David Esenowo

doi:10.1016/j.heliyon.2024.e27868

Reduction of polystyrene/polyurethane plastic wastes from the environment into binders for water-resistant emulsion paints

Heliyon. 2024 Mar 13;10(6):e27868. doi: 10.1016/j.heliyon.2024.e27868. eCollection 2024 Mar 30.

Affiliations

¹ Department of Chemistry, Modibbo Adama University, PMB 2076, Yola, Nigeria.
² Department of Science Laboratory Technology, Modibbo Adama University, PMB 2076, Yola, Nigeria.
³ Department of Chemical Engineering, Modibbo Adama University, PMB 2076, Yola, Nigeria.
⁴ Department of Chemistry, Federal University Wukari, PMB 1020, Taraba State, Nigeria.

Abstract

Waste management is fundamental to resource and environmental sustainability. Expanded polystyrene (EPS) and polyurethane (PU) waste plastics were recycled and applied as binder in emulsion paint formulation. The recycled polystyrene (rPS) and polyurethane (rPU) were blended into composite resins, where toluene was used as the solvent. The blends of rPS and rPU were optimized, while some physicochemical properties of the composite blends (rPS/PU) were evaluated. The results showed that the incorporation of rPU into rPS increased the viscosity (1818 mPa-3924 mPa), rate of gelation (dry-to-touch time: 15 min-0.25 min), moisture content (2.7%-8.1%), moisture uptake (3.2%-5.0%), solid content (48%-53.4%) and density (0.82 g/cm³ to 1.050.82 g/cm³) of the rPS/PU composite resins. Characterization was carried out using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and atomic force microscopy (AFM). The results summarily showed that there are interactions among the rPS and rPU molecules in the composite, where complimentary structural and morphological characteristics were also achieved. The composite resin also exhibited superior bond strength (0.5-4.24 Mpa) on wood, cast mortar, ceramic, and steel surfaces due to its stronger intra- and inter-surface interactions compared to the neat rPS resin. The composite resin was used as a binder in the formulation of emulsion paint. The paint exhibited stronger resistance to water, among other superior properties, when compared to the paints formulated using neat rPS and conventional polyvinyl acetate (PVA) resins. The reduction of plastic waste in this study holds potential for the production of highly water-resistant emulsion paint for outdoor and indoor applications.

Keywords: Composites; Emulsion paints; Recycled plastics; Water-resistant coatings.