Production and characterization of an ecofriendly polystyrene waste adhesive made with toluene–acetone solvent

Polystyrene waste was converted into an ecofriendly adhesive using a toluene–acetone solvent system and compared to that of toluene solvent. The bond strengths of the adhesives were determined. The adhesive with the maximum bond strength was tested for pH, water content, flow behavior, the effect of temperature on viscosity, thermogravimetric analysis, and differential scanning calorimetry. The influence of viscosity on the adhesive bond strength was checked. Fourier transform infrared spectroscopy was used to identify the functional groups in the adhesive, and the effect of toluene and acetone solvent mixing on the bond strength of the polystyrene waste adhesive (PSWA) was determined. An increase in polystyrene concentration increased the adhesive viscosity. Temperature changes did not influence the adhesive's pseudo-plasticity but influenced its viscosity, as temperature rise resulted in a viscosity decrease. The toluene–acetone PSWA sample with a viscosity of 615.01 cP provided the best bond strength and a further decrease or increase in viscosity reduced the bond strength. The bond strength of the toluene–acetone adhesive system was significantly lower than that of the toluene system. The toluene–acetone system, on the other hand, is more environmentally friendly than that of toluene, and its maximum bond strength value of 0.637 N/mm² is within the range of bond strength values for particleboard production. The eco-friendlier adhesive has a pH of 5.76 and a water content of 5.82% which are also within the range for particleboard adhesives. The eco-friendlier PSWA is more thermally stable with a slower thermal decomposition rate than that of the toluene (control) sample. Its pseudoplastic flow behavior is advantageous for adhesive applications.