Polyolefin upcycling through dynamic covalent crosslinking

Statement of the problem or situation: Recycling polyethylene (PE) and polypropylene (PP), the two most common plastics accounting for more than 40% of global plastic consumption, has been a big challenge because of the quality deficiency of the recycled materials. PE and PP cannot be sorted cleanly and are often recycled as a mixture due to their similar structures and densities. However, PE and PP are immiscible and their simple blends have poor mechanical properties. How the problem being addressed: To improve the quality of post-consumer or post-industrial recycled polyolefin blends (mainly PE and PP) for their reuse and achieve the mission to “upcycle plastic waste for the circular economy”, RockyTech has developed a compatibilization technology called WeCAN (Waste-based Covalent Adaptable Network), which takes the form of reactive compatibilizers. The key strategy is incorporating reversible covalent bonds into polyolefin linear chains to enable their crosslinking at the particle interface, thus achieving polymer fusion with minimal micro-and macroscopic phase separation and quality enhancement. What was done in Phase I: We have developed two working prototypes of polyolefin compatibilizers (RevLink-101 and RevLink-201, patent pending), which can enhance the quality of PE and PP blends to similar tensile properties as virgin high-density polyethylene (HDPE). What is planned for Phase II: To accelerate the commercialization of the compatibilizers, we will further optimize the processing conditions, develop compatibilizer masterbatches, perform various material testing to obtain the necessary certification, and perform pilot runs to validate the scalability and gauge the economies of scale. Commercial applications and other benefits: The proposed upcycling of polyolefins will give these polymers a new life by transforming them into value-added products and realizing their circular lifecycle while reducing the accumulation of plastic waste. Our compatibilizer technology allows cheap, low-quality and unsorted plastics to be effectively upcycled with speed and efficiency, thus providing solutions to the quality deficiency problem that plastic recyclers and processors are facing currently. The upcycled polyolefins made from post-consumer or post-industrial polyolefin waste can be used in end-user products in many industries, such as 3D printing, consumer electronics accessories, auto parts, sports equipment, packaging, and construction. Thus, we are developing manufacturing processes and technologies that could benefit the whole plastic recycling and processing ecosystem.