Fossil feedstock-based plastics contribute to CO2 emissions during extraction of feedstock, polymer production and end-of-life. Bio-based plastics have the potential to avoid fossil CO2 emissions, but since their performance is limited, they are so far only used in single use applications. The potential of environmental impact reduction (CO2 emissions, but also land and water use) through bio-based plastics can be exploited to its fullest when effective recycling is applied. Polylactic acid (PLA) is the prime bio-based polymer that is readily available and recyclable. Moreover, the application of this polymer can be greatly extended when the physical and mechanical properties of PLA polymers can be varied, providing a world first real entry of biobased plastics into demanding applications. This is achieved by polymerization of advanced grades PLA with specific ratios of the d- and l- monomers. The use of such advanced PLA grades allows for producing complex all-PLA products such as furniture, composites and rugs. However, chemical recycling of such products back to the advanced PLA grades, is currently impossible which hampers the market introduction of these advanced grades.
Objective of the project
Currently, the recycling of advanced grades of PLA back into complex applications is hampered by the formation of a racemic mixture of PLA monomers during depolymerization, that makes it impossible to obtain the original grades back. Without a breakthrough solution, downgrading of such high-performance PLA products is only possible into plain grades that can be used to replace single used plastics. This shortfall of a real closed loop is the trigger to find the missing link to close the loop. Therefore, this project is targeted at identifying a technologically, economically and ecologically feasible recycling route for these advanced PLA grades. REPLACER will test the feasibility of the chemical recycling of PLA polymers from various forms (e.g. composite, fiber and foam) with varying composition of l- and d-monomers. The depolymerization process is to be combined with a chiral separation process for the enantiomeric monomers. Monomer fractions with defined enantiomeric composition are to be obtained so that they can be repolymerised to produce advanced grades of PLA.
Description of activities
Several possible process routes will be assessed for their potential to recycle a waste stream consisting of different advanced grades of PLA back to PLA polymers that have their original composition to enable their re-use in complex products. A desk study will evaluate the different recycling routes (Kiduara, TNO), where the objective requirements will be set on the materials to recycle and the level of quality to be obtained (Arapaha). Then, experimental verification and development will be performed for the depolymerization, chiral separation and repolymerisation steps (TNO, NHL Stenden) to evaluate the true applicability of the technologies to recycle advanced grades of PLA back into new PLA matrials. Samples produced by the different routes will be evaluated for their purity and properties (NHL Stenden). By performing a techno-economic and environmental evaluation of the routes (TNO), the route with the best economical perspective and smallest impact can be identified. Finally, the first steps towards scale-up are taken as well as the identification of replication potential to other polymers (Arapaha). The results will be disseminated to stakeholders and the public (Arapaha).
The project will result in a blueprint for a process to recycle all grades of PLA plastics in a fully circular manner, based on experimental proof. The outcome serves as base for further design and development of this process with the partners of this consortium, with the objective to bring this technology into practice as an extension of the existing industrial facilities for PLA production and recycling. Taking away the bottleneck for recycling of these novel advanced grades of PLA plastics allows for widespread use of these versatile materials, that are by then not only bio-based but have become also fully circular. This allows companies in the Netherlands to strengthen their position in developing renewable carbon-based circular economy and simultaneously increase their market share. Furthermore, the project contributes to a significant reduction of CO2 emissions because these circular bio-based plastics will replace currently used fossil-based plastics that are incinerated at end-of-life.