State-of-the-Art of the Thermal Molding Technologies for Plastic Recycling

The increasing generation of plastic waste and the limited efficiency of recycling systems demand technologies capable of transforming recovered materials with stability and performance. The objective of this systematic review was to synthesize recent advances in thermal molding technologies applied to plastic recycling. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The search was carried out in the Scopus and Web of Science databases on May 27, 2025, applying filters for accessibility, language, document type, and the 2014–2024 period. After screening and the application of inclusion and exclusion criteria, 26 articles were selected for qualitative analysis. The results indicate that injection molding is the most widely used technology for processing recycled polymers, followed by compression molding and, less frequently, rotational molding, thermoforming, and cast film processes. Recycled polyolefins (polypropylene and polyethylene) predominate as raw materials, whereas polyethylene terephthalate, polystyrene, and acrylonitrile butadiene styrene show lower usage frequency. The evidence indicates that process parameters, compatibilization, reinforcement, and thermal history have a decisive influence on molding efficiency and the performance of recycled materials. In addition, advances were identified in equipment development and in the integration of pre-conditioning stages. Overall, the findings suggest that an integrated approach combining thermal control, formulation, and process design is essential to improve the stability and quality of products manufactured from recycled polymers.