The experiment and simulation of enhanced mechanical performance for polyethylene terephthalate/high-density polyethylene composites via domain size control

Solid-state shear milling (S3M) equipment is proficient for achieving roomtemperature ultrafine grinding of multicomponent polymers, demonstrating significant potential in polymer blending and waste plastic recycling. However, a systematic investigation of S3M's ability to control the domain size of multicomponent polymer is currently lacking, which was of great potential for the high-value recycling of waste plastics that are difficult to separate and thermodynamically incompatible. As the raw material of beverage bottle, polyethylene terephthalate/high-density polyethylene (PET/HDPE) system with tremendous production was hard to be recycled together. Therefore, in this study, we chose PET/HDPE for the study of domain size control efficiency of S3M on mechanical properties of polymer blend. We also measured the processing parameters during the fabrication of PET/HDPE blended powder to determine the optimal manufacturing parameters for the polymer composite with outstanding mechanical property. After 30 milling cycles, the powder size of PET/HDPE gradually decreased from 849.8 mu m (2 cycles) to 43.2 mu m, which related to PET domain size of 71.9 and 5.2 mu m, respectively. Meanwhile, at 24 milling cycles, the PET/HDPE composites reached the highest tensile strength of 27.6 MPa, meeting the most proper milling condition for PET/HDPE system. Finite element computer simulation was introduced to further investigate the domain size influence on mechanical property of PET/HDPE composites, which acquired similar results with the experimental value before excessive milling cycles. Based on both the experimental results and simulation support, a theoretical basis for the domain-size-control analysis of S3M in multicomponent waste polymer recycling was established.