Our robot turns plastic waste from 3D printers into new forms. This waste consists of a type of plastic called PLA, made from starch (often from the corn plant), which is biodegradable, but would decompose very slowly compared to other bio-waste. In most industrial recycling plants, PLA is not separated by type and is simply burned, although special conditions in some industrial composting plants allow for the degradation of PLA within a few months. Conventional plastics, often extracted from crude oil, remain in nature unaltered for hundreds of years. In order not to waste the energy used for its production, the most ecological solutions are therefore firstly prevention and secondly multiple use and recycling, despite this plastic being biodegradable.
During our residency, we asked Professor Michael Shaver from the Green Materials Laboratory at the University of Manchester about plastic recycling and how to approach the technical implementation of our project. For example, he explained to us that it is not possible to de-colour plastic, only to colour it more and more. So the more different colours are mixed together when melting, the more brown and unsightly the new plastic object becomes. In industry, the plastic is then coloured black by adding burned carbon materials, which makes the resulting products more attractive but also the most difficult to recycle.
Professor Michael Shaver also explained to us why plastic cannot be melted down infinitely and brought into a new form. Due to the sheer forces and temperatures that occur, the material loses properties with each cycle, the viscosity gradually drops and the material becomes brittle. He estimates that with our extruder robot, eight cycles could be possible before the material becomes too brittle. We are curious to see how the visible properties of the resulting objects change with each cycle, and hope the project will contribute to promote public discourse around plastics.