Evaluation of the recyclabillity of a lignin-based biopolymer

Sammanfattning: The use of plastic materials has changed the packaging industry, the construction industry, the automotive industry, and many others drastically. Plastics are also abundant in our everyday life. However, its downsides in the society are undeniable and are starting to get attention from law makers, the general public and industries alike. Because of their reliance on fossil feedstock and persistence in nature, efforts are being made to make plastics biobased as well as improving recycling of the material. However, the recycling process is complicated, unoptimized and also differs depending on the product and the country. The differences include the techniques and technology used for sorting, the plastics which are prioritized, and where they end up. This project investigated the recyclability of Renol®, a biopolymer based on lignin, a residual product from the forest industry. To do this, first it was established the most interesting viable thermoplastic resin for the Renol was PP. This was because one of the uses for Renol is in plastic packaging, where PP is one of the most recycled materials. Different compositions of the PP/Renol blend were then produced, containing 5, 10, 20, 30 and 50wt% Renol. Density testing and infrared spectroscopy were then used to determine the highest percentage by weight of Renol that could be included for the material to still be detected as PP in a plastics recycling station. For density, the highest concentration was determined to be 46wt% and 27wt%, for sorting methods using 1.00g/cm3 and 0.95g/cm3 as their thresholds, respectively. Using near-infrared technology and computer algorithms by TOMRA (the European company leading the industry in sorting materials), this value decreased to 20wt%. The quality of recycled polypropylene with Renol (Ren25 and Ren50) and without (rPP) was then measured using the tests stated in the RecyClass protocol for PP containers. It was found that both Ren25 and Ren50 had an elongation at break which was too low compared to rPP. There was a woody smell in the materials Ren25 and Ren50. This was reflected in the measurement for volatiles, where the materials were inserted into a 180°C oven and Ren50 lost the most mass out of the three materials. If the material were to be sent to an official recyclability test, it would most likely fail with the elongation at break, the smell and the volatile substances. In a packaging context it would most likely be sorted and recycled as colored PP at a maximum of 20wt% Renol and for other products with PP, most likely at a maximum of 46wt% Renol.