Summary: Over the last several decades, the process of recycling polymer waste has been attracting the attention of many scientists working on this issue. Polymer recycling is very important for at least two main reasons: firstly, to reduce the ever increasing volumes of polymer waste coming from many sources: from daily life packaging materials and disposables and secondly, to generate value‐added materials from low cost sources by converting them into valuable materials similar, to some extent, to virgin materials. Poly(ethylene terephthalate) (PET) occupies the top of the list of polymers to be recycled due to its easy recycling by different ways, which, in accordance, give variable products that can be introduced as starting ingredients for the synthesis of many other polymers. PET can by recycled by hydrolysis, acidolysis, alkalolysis, aminolysis, alcoholysis and glycolysis. Glycolysis is the breakdown of the ester linkages by a glycol, resulting in oligomers or oligoester diols/polyols with hydroxyl terminal groups. Oligoesters coming from the glycolysis of PET waste have been well known for a number of decades to be utilized as a starting material in the manufacture of polyurethanes, unsaturated polyesters and saturated polyester plasticizers. But, as a current motivation, we are reporting on a new application for these oligoester diols/polyols by converting the hydroxyl terminals into acrylate/methacrylate groups. These new acrylated/methacrylated oligoesters have been tested as UV curable monomers and gave promising results from the point of view of their curability by UV and their mechanical properties. The new motivations open the potential for the market to apply the depolymerization products of PET waste for UV curable coatings, useful for wood surfaces, paints and other applications.Recycling of PET polymer by different chemical routes.magnified imageRecycling of PET polymer by different chemical routes.

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PET waste obtained from beverage bottles was depolymerized by a glycolysis reaction, using diethylene glycol (DEG) as the glycolyzing system and manganese acetate as a transesterification catalyst. The glycolysis reaction was conducted at two different molar ratios of PET : DEG, namely 1 : 2.15 and 1 : 1.03, for the sake of obtaining oligoester polyols of varying molecular weights. The hydroxyl values of the obtained oligoesters were 361 and 330 mg KOH/g. Modification of these oligoester polyols was carried out by acrylation reactions of the available hydroxyl groups by acryloyl chloride. This gave acrylated oligoesters curable under UV or electron beam irradiation. The curability of these newly synthesized acrylated oligoesters was tested by UV irradiation, in the presence of 2‐benzyl‐2‐dimethylamino‐1‐(4‐morpholinophenyl)‐1‐butanone (BDMB) as a photo initiator. This gave cured films of high mechanical properties when the acrylated oligoesters were either cured alone or as mixtures with other commercially available diacrylate/dimethacrylate monomers. The measured tensile properties were in the range of 4.62–45 MPa for maximum tensile strength and 0.074–2.0 GPa for Young's modulus.

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