Co-authors​ :

 P. HAO (BELGIUM), Charmayne SIEBERS (NETHERLANDS), K. RAGAERT , F. A. GILABERT (BELGIUM) 

The increasing volume of non-biodegradable thermoplastic waste urgently necessitates recycling solutions, as this waste presents environmental threats and requires resource-intensive production processes. These thermoplastics can be fully integrated in the production loop of advanced composites as they offer important advantages such us melt-reshapability and mechanical performance. Presently, mechanical recycling of thermoplastics is prevalent, favored for its efficiency and low cost. However, this method often fails to yield high-purity recyclates from a single polymer type. Classified bales typically contain minor quantities of other polymers, acting as contaminants. A recent study on four major types of polyolefins (PO) subjected to tensile load demonstrates that the mechanical response is significantly influenced by the material's nature and its microstructure [1]. This discovery complicates the characterization of recycled polymer blends: (i) mechanically recycled polymer blends (or contaminated polymers) are multi-phase materials; (ii) most thermoplastics used in blends are semi-crystalline, inherently bi-phasic, comprising both amorphous and crystalline phases; (iii) the interactions between different polymer components are not fully understood, including their compatibility and interface bonding. Consequently, these post-consumer plastics often result in downcycled materials of diminished quality and/or utility, leading to their low acceptance in secondary markets and impeding the recycling of polymers and polymer-based composites.

The nonlinear thermomechanical behavior of polymer blend matrices plays a crucial role in determining the rate and temperature responses of composites. An advanced model, building upon a unified constitutive formulation originally developed for pure polymers [2], has been created to analyze various mix compositions of polymer blends, focusing on texture-related properties (Figure 1). The accuracy of the model in capturing rate-sensitivity, along with self-heating and thermal softening effects, was validated through tension tests using a high-speed 3D stereo Digital Image Correlation (DIC) system and an infrared camera. Additionally, micromechanical models based on the Representative Volume Element (RVE) approach were utilized for numerical simulations, aiming to assess the overall behavior of blend-based Unidirectional (UD) composites via homogenization techniques. The primary objective of this research is to compare the performance of composites made from recycled plastics with those made from virgin materials. This comparison is intended to promote eco-friendly design by optimizing the mechanical properties of recycled composites and providing essential data to improve the mechanical recycling process. Such advancements are expected to enhance the usability of post-consumer plastics and contribute to the reduction of plastic waste.