Deinking Printed Plastic Using Nonionic Surfactant and Cationic Polymer

Abstract

Plastic recycling has been an ongoing conversation amongst many environmentalists who aim to reduce consumption and use of plastic. Prior to reducing plastic use, it is crucial to consider the current process of recycling and its effect on inked plastic. Recycling plastic which contains ink degrades the mechanical and optical properties, limiting its use while adding to the weight of the landfill. Our research work focuses on deinking plastic with nonionic surfactant (NPEO10) and cationic polymer (PEI) mix to remove residual ink from LDPE to regain mechanical and optical properties. The research indicated NPEO10 alone was able to deink at 6.25mM, 12.5mM and 25mM at pH 12 after 4 and 24 hours of agitation. PEI alone was unable to deinking at pH 5 or 12 but deinking was noticed with 1:1 mass ratio of NPEO10 and PEI at pH 12 after 24 hour deinking. Blue ink was harder to remove than green ink and required additional scraping of the surface. Tensile tests performed for 1:1 mixtures indicated deinking increased stress at break while colorimeter tests indicated decrease in color, as expected. DSC measurements suggested a change in crystallinity by 5-6% between non processed (not deinked, extruded or compression molded) and processed samples (deinking, extruded and compression molded or extruded and compression molded) which was also indicated by yield points in stress vs strain graphs.