In previous periods, WP1 to WP3 were completed and the project reached Milestone 2 with the construction of two multisensor tools. These prototypes allow to classify the laminated glass by different categories separated by the plasticizer type in PVB-based interlayers and quality (in terms of haze and transmittance) of the interlayers. This allows to split the glass wastes before the recycling process and as result has a positive impact on the final quality of the recycled polymer. The tool is based on analysis of the spectroscopic data (NIR, Raman and transmittance) of interlayer and implements a software with developed AI algorithms for classification.
During the last year, demonstration phase of the multisensor and the recycling process itself has been performed completing Milestone 3 and 4 (WP4). In addition, sorted recycled PVB materials obtained from DEMO sites has been processed in different formats in WP5 (pellet, film, dispersion, solutions) and incorporated in applications in WP6. The following results have been achieved:
• Validation of the multisensor operation. More than 1 ton of glass wastes were analysed by multisensor tool and the measurement time was 33 s per waste glass, meaning a sorting capacity of ~109 glasses/hour (equivalent of >25 tons of waste glasses per day). The validation results showed high classification score for type of the interlayer polymer as well as for the main plasticizer (>90%), however, prediction of plasticizer content could be improved. Optical properties including haze were accurately determined allowing to their classification by quality.
• Demonstration of a mechano-chemical treatment for recycling PVB in order to reduce glass content below 0.5 % from automotive and construction wastes (recycling capacity of 544 ton/year). Category 1 (high quality wastes) can be obtained with inorganic contents below 0.3 %.
• A Decision Support Tool (DST) for the optimisation of the recycling steps has been created based on modelling of the mechano-chemical recycling steps. The tool has been validated using process data from the pilot test sites.
• The use of antioxidant has been validated as a closed loop recycling strategy for post consumed PVB wastes. Screening of antioxidants was tested at pilot scale confirming that the selected AOs offered resilience against degradation at reprocessing and protection during the next service life of the material.
• Demonstration of the use of re-PVB in different prototypes. Promising results have been obtained for interlayer use, coatings and batteries (both as binder in electrodes and as separator). On interlayer use, mixtures of virgin and re-PVB have achieved necessary levels of mechanical properties, thermal and humidity resistance. For optical properties, the results are close to the requirements, and the main issue appeared with reprocessing operations and external contaminations affecting the results even when working with reference material.
• LCA analysis confirmed the environmental and health benefits of the new recycling process. Economically, the recycling process has been also assessed and the re-PVB obtained price comparable to market prices.
• Good management practices have been published for glass recycling companies who are looking into recycling the PVB fraction from the laminated glasses.
All the work developed during the project has been actively disseminated. The project has resulted in the definition of 13 KERs, considering not only the solutions developed for recycling but also end uses of re-PVB. Active engagement of stakeholders, including glass recyclers, glass and PVB manufacturers, in the assessment of the project results has been achieved. The standardization of the re-PVB characterization has been published in a new CEN Workshop Agreement CWA 18174 “Plastics — Recycled plastics — Characterization of polyvinyl butyral (PVB) recyclates”. Knowledge generated has resulted in publication of 6 scientific papers.
