A low environmental impact emulsion process as an alternative to the conventional recycling methods of plastic wastes

Conventional plastic recycling by melting or burning costs energy and produces secondary contamination. This paper presents a facile and low-energy-impact recycling procedure by converting single-use plastics into colloidal polymer nanoparticles. In this procedure, solutions of these polymers in organic solvents were first made into stable emulsions in surfactant solutions. Removing the solvent from the emulsion then rendered a stable suspension of colloidal nano polymer particles. Although the principles are simple, technical challenges of conducting the procedure abound. Shear-induced emulsion with its process dictated by the onset of the Taylor instability is governed by a few physical parameters, including the viscosity of the polymer solution, the interfacial tension between the polymer solutions and the aqueous phase, and the shear rate; choices of solvents and surfactant are critically important. This study examined the effects of the above control parameters on the final particle sizes, size distribution, solid contents, times required to remove solvents from the emulsion, and the long-term stability of the final latex suspensions. Energy cost, including shear and recovery of the solvents for reuse, will be estimated for comparison with that of conventional methods for recycling similar polymers.