Enhancing and hindering biodegradation: A comparative study on polyamide 6 reinforced with bio-fillers (peanut shell, olive pomace, and plaster)

In recent years, bio-reinforced composite materials have occupied an important class among the materials of mass use in our daily lives thanks to their potential advantages such as lightness, low cost, ease of implementation, and in particular biodegradation. The latter has been the objective of several studies focusing particularly on poorly biodegradable polymers, among these polymers we find polyamide 6 (PA6). It is a semi-crystalline polymer, distinguished by its good mechanical properties, excellent chemical and thermal stability, and low price compared to other polyamides. In this research, we investigated the impact of reinforcing PA6 with peanut shell powder (PSP), olive pomace powder (OPP), and plaster (PL) on its biodegradation process. Our objective was to determine whether the incorporation of these reinforcements accelerates, delays, or has no effect on PA6 biodegradation. To achieve this, we conducted degradation experiments using the bacterium Alcaligenes faecalis (AF), isolated from the public landfill of Meknes, Morocco. Our findings revealed intriguing insights into the biodegradation behavior of the PA6 composites. Specifically, the incorporation of PSP significantly enhanced PA6 biodegradation, resulting in a notable 38 % weight loss. Conversely, the inclusion of OPP led to a delay in biodegradation, with only a 19 % weight loss observed. Interestingly, the addition of plaster exhibited a biodegradation pattern similar to that of raw PA6. Furthermore, we utilized FTIR and SEM coupled with EDS elemental analysis to confirm the biodegradation of the composites. These techniques provided valuable insights into the structural, morphological, and elemental changes undergone by the composites during the biodegradation process. Overall, our study contributes novel insights into the biodegradation dynamics of PA6 composites reinforced with natural materials. By elucidating the effects of reinforcement on biodegradation, our research paves the way for the development of sustainable and eco-friendly composite materials.