A Novel Approach to Synthesis Alkyd Resin from Recycled Polyethylene Terephthalate (rPET)

ABSTRACT: Reducing carbon footprints is an essential requirement in the chemical industry. Researchers are concentrating on creating sustainable products derived from renewable resources or waste materials. Polyethylene terephthalate (PET) waste significantly contributes to carbon footprints; the chemical recycling of PET waste possesses extensive opportunities within the chemical sector. For instance, PET waste can be transformed into valuable alkyd resin, which is utilized in the production of oil-based paints. This research work focuses on the synthesis of long oil alkyd resin using recycled polyethylene terephthalate (rPET). As the incorporation of rPET in alkyd resin has several limitations such as two-step synthesis, inability to produce long oil alkyd, and long drying time. To overcome these limitations, a novel synthesis route has been devised to produce long oil alkyd resin. In this study, three long oil alkyd resins were synthesized, each containing varying amounts of rPET. The presence of rPET in the alkyd resins was confirmed by spectroscopic techniques. To assess the impact of rPET content on alkyd resin, physicochemical properties, performance testing, and instrumental analysis have been conducted. A comparison is made between these resins and the benchmark long oil alkyd resin, and the results are discussed. Furthermore, to synergize the coating applications, viscoelastic behavior and mechanical properties of the dried films were assessed, including exterior durability. Alkyd resin containing 8% rPET shows performance properties that are comparable to the benchmark alkyd resin. This alkyd requires 80 min for surface drying and 4 h to reach a tack-free state. It has a gloss value of 86 at 20° angle. The scratch hardness is recorded as 900 g, while the gloss retention stands at 88.34% following 240 h of QUV exposure. This novel synthesis route helps to incorporate the rPET in the alkyd backbone with reduced carbon footprint to meet the goal of sustainability and the circular economy.