Effect of fiber surface treatment with silane coupling agents and carbon nanotubes on mechanical properties of carbon fiber reinforced polyamide 6 composites

In recent years, the demand for environmentally sustainable materials has led to the exploration of biodegradable composites as alternatives to fossil-based polymeric matrices. Among these, poly-epsilon-caprolactone (PCL) has emerged for its versatility and broad applicability. However, challenges such as limited mechanical strength and thermal stability demand innovative approaches for enhancement. This study focuses on the development and characterization of hierarchical composites of PCL, ramie fibers, and graphene oxide (GO) to address these challenges. Differential scanning calorimetry (DSC), x-ray diffraction (XRD), contact angle, surface energy, mechanical properties (impact and tensile), scanning electron microscopy (SEM), and ecotoxicity assays were employed for evaluation. Results indicate that the inclusion of GO and ramie fibers alters the thermal properties, increasing melting enthalpy and crystallinity due to GO's nucleating effect and fiber-induced steric hindrance. Increased hydrophilicity and surface free energy suggest enhanced biodegradation potential. Ecotoxicity tests confirm non-toxicity, while SEM reveals low interfacial adhesion between the fiber and matrix. Tensile tests reveal no synergistic effects, although GO enhances biodegradation without compromising mechanical integrity. The presence of GO and ramie fibers does not induce toxicity, as evidenced by normal seedling growth. While hybridization does not significantly impact mechanical properties, GO offers avenues for enhancing biodegradability and expanding ramie fiber applications. This study highlights the impacts of filler integration on the properties of PCL, indicating pathways for tailored material design aimed at sustainable solutions.