ABSTRACT Global plastic production currently exceeds 400 million metric tons annually. Due to the short service life of plastic products, the amount of waste is constantly rising. Recycling this heterogeneous waste is essential; however, the diverse composition of plastic waste presents challenges in reprocessing, easily resulting in polymer blends. This study combined X‐ray computed tomography (X‐CT) and scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM–EDS) to characterize real, unwashed recycled plastic blend. Low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), and polyethylene terephthalate (PET) wastes were melt‐blended using two different temperatures: 210°C and 270°C, typical for processing of polyolefins and PET, respectively. Unlike studies based on clean laboratory blends, this study quantified PET dispersion and the influence of contaminants and processing temperatures on mechanical properties. The findings revealed that higher processing temperatures resulted in a more uniform structure by reducing PET particle size and void content, but decreased tensile strength and elastic modulus by 7% and 10%, respectively, due to thermomechanical degradation, as evident by a reduction in molecular weight. These findings highlight the challenge of optimizing processing conditions for heterogeneous plastic waste, where structural uniformity and mechanical performance can conflict. Balancing these factors is essential for effective use of recycled materials.
Rasilainen et al. (2026) studied this question.