A review of flax fiber reinforced polylactic acid composites as green polymeric materials: Ageing properties, sustainability, challenges and future perspectives

Synthetic fiber composites (SFCs) have various engineering applications because of their high mechanical performance with lightweight characteristics. However, their un eco-friend and unsustainability behavior led to a shift towards green composites. Yet, the qualities of NFCs have its own limitations due to its hydrophilic nature and low thermal stability issue. Therefore, natural fibers have been chemically treated to improve these constraints for better performances, however, on the other hand these chemicals will challenges the greening environment. Thus, after use, composite materials should be aged and composited in to environment for better ecosystem. When green composites are exposed to some external ageing conditions its properties will become degraded. Therfore, this review targets to show natural fiber reinforced polymeric composites, (specifically flax reinforced polylactic acid composites) are greener and more sustainable than synthetic fiber composites with more specific and detailed ways compared to that of related documented reviews. The moisture and hydrothermal accelerated aging methods were focused to analysis ageing properties of the flax-bio composites. This review research showed, the degree of greenness of the polymeric composites could depend on the specific reinforcing fiber types, its quantity of environmental impact in its life cycle and the matrix material properties used in the composites. Furthermore, the applications of flax composites in several areas were described. Finally, the review summarizes the findings of the existing literature and has suggested key insights for possible future consideration in the field.