Development of an experimental setup for microwave assisted drying of PET; a feasibility study

Abstract

With high global ambitions for sustainability and circularity and increasing energy prices, the recycling industry keeps innovating to keep up with political goals and customer demand. Reducing the energy consumption in the recycling process reduces environmental impact and reduces financial costs for the customer. A energy intensive process step in recycling is oven drying the plastics to an acceptable moisture content. The energy cost can be reduced by using microwave irradiation as heat source. This research investigates the moisture content and the intrinsic viscosity (IV) of polyethylene terephthalate (PET) during and after the drying process. The measurements of the PET dried in an experimental setup employing microwave irradiation as heat source is compared to the drying process in a oven at 80, 100 and 150 ◦C. The IV of the virgin PET pellets did not decrease significantly after drying in the experimental setup, but it did decrease after drying in the oven at 150 ◦C. The moisture content decreases more rapidly in the oven at all temperatures than in the experimental setup. Scaling up the experimental setup should increase the drying rate. No indications of unfeasibility of microwave assisted drying are found. Keywords: PET (polyethylene terephthalate), Circular economy, Plastic recycling, Intrinsic viscosity (IV), Moisture content