Mechanical Recycling of PA66-Based Composites: Performance, Degradation and Environmental Trade-Offs in a Circular Economy Context

Busra Burcu Yalamacilar; Kozet Yapsakli; Baris Calli

Authors

Busra Burcu Yalamacilar Marmara University https://orcid.org/0000-0002-0807-2733
Kozet Yapsakli Marmara University https://orcid.org/0000-0001-6239-6272
Baris Calli Marmara University https://orcid.org/0000-0002-7234-0771

Keywords:

Polyamide 66, Waste Recycling, Life Cycle Assessment (LCA)

Abstract

The transition toward a circular economy for engineering plastics requires sustainable end-of-life strategies for complex, additive-containing materials. Polyamide 66 (PA66)-based composites pose significant challenges due to their multi-component structure and stringent performance requirements, particularly in flame-retardant (FR) systems. This review evaluates the mechanical recycling of PA66 composites by linking thermomechanical degradation with environmental performance and risk considerations.
Key degradation processes, including polymer degradation, reinforcement damage, and additive-related effects, are assessed in relation to mechanical integrity and fire-safety compliance (e.g., UL 94). Particular attention is given to the environmental implications of FR systems, such as additive stability, potential emissions during reprocessing, and persistence in recycled materials. The concept of a “performance safety margin” is introduced to define allowable property degradation while maintaining regulatory compliance.
Life Cycle Assessment (LCA) indicates that mechanical recycling can reduce global warming potential and energy demand compared with virgin PA66, although benefits are constrained by processing conditions and substitution limits. A performance–environment trade-off framework is proposed to support material selection and recycling decisions, synthesized from comparative analysis of literature-reported relationships between mechanical property retention, recyclate content, and environmental impact metrics.
Overall, the literature suggests that mechanical recycling is most effective within a moderate recyclate-content window, often around 20–50%, where functional performance and environmental benefits can be balanced.

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Mechanical Recycling of PA66-Based Composites: Performance, Degradation and Environmental Trade-Offs in a Circular Economy Context

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