Nitrogen Poisoning of HDPE and LLDPE based on Chemically Recycled Post‐Consumer Plastic via a Kinetic and Microstructural Modeling Technique

Chemical recycling of plastic waste has promise as a complementary technology to increase eco-efficiency of plastics life cycles. Accumulation of impurities in feed streams can affect sensitive compounds such as the Ziegler-Natta catalyst systems commonly used to produce polyolefins such as high density polyethylene (HDPE) and linear low density polyethylene (LLDPE). In a poison study, the influence of impurities-more specifically NO and N2O-on the catalyst system are investigated comprehensively in terms of kinetic behavior and activity rates. A product composition analysis gives insights into product properties such as molecular weight distribution (MWD), comonomer composition distribution (CCD), melting point, and crystallinity. By applying known modeling techniques (kinetic modeling, MWD, and CCD deconvolution modeling), information beyond analytical data is obtained. The results of the study show that both poisons significantly affect catalyst kinetics and reduce catalyst activity. N2O influences primarily the MWD, while NO poisoning strongly affects the CCD of LLDPE samples. Since the mechanical properties of the polymers produced depend on factors such as MWD and CCD, NO and N2O poisoning may reduce their processability and applicability.