Potential of Pyrolyzing Mixed Polyethylene Terephthalate and Polypropylene Plastic Wastes for Utilization in Asphalt Binders

Abstract

The recycling of plastics is a crucial element of efforts to reduce the environmental impact of plastic waste. While thermoplastic plastics can be reshaped and recycled, thermoset plastics are not recyclable due to their inherent stiffness. To meet the ambitious plastic waste targets set by the European Union for 2030, new thermochemical processes such as pyrolysis are being explored. In this study, we investigate the potential of pyrolysis to mix two different types of thermoplastic plastics, namely polyethylene terephthalate and polypropylene, and examine the correlation between composition, structural and chemical properties, and electromagnetic wave absorption performance through X-Ray Diffraction (XRD) analysis. The pyrolysis was conducted using a retch 5min+5Hz method in the laboratory with a ratio of 1:1 for the two plastics. Our observations reveal that polyethylene terephthalate plastic melts at 260℃, while polypropylene melts at 160℃. We found that the heated and unheated plastics had the same diffraction pattern, but with varying degrees of intensity. The pyrolyzed plastic wastes were successfully fused by heating at 100℃ for 30 minutes. Our XRD analysis indicates that the characteristic spectral lines of each polymer can be clearly distinguished, and the intensity varies with the composition of the plastic mix. The pyrolyzed plastic wastes showed potential to replace aggregates in asphalt mixes. In conclusion, our study demonstrates that pyrolysis is a promising method for mixing and recycling thermoplastic plastics. The structural and chemical properties of the mixed plastics can be analyzed through XRD analysis, which can provide valuable insights into the correlation between composition and electromagnetic wave absorption performance. The potential for using pyrolyzed plastic wastes as a replacement for aggregates in asphalt mixes highlights the potential for this method to contribute to the circular economy and reduce the environmental impact of plastic waste.