Preparation of carbon fibre-reinforced composite panels from epoxy resin matrix of nano lignin polyol particles

Carbon fiber reinforced composite materials possess the advantages of being lightweight, high strength, and high modulus, making them extensively utilized in various domains including military, livelihood, and aerospace. However, the conventional resin matrix used in composite materials primarily consists of bisphenol A epoxy resin which has drawbacks such as low toughness, exorbitant cost, and environmental and human health hazards. Additionally, traditional bisphenol A epoxy resin is a non-renewable organic chemical raw material that does not melt or dissolve after permanent cross-linking and solidification, thus making degradation very difficult while hindering recyclability. In order to enhance the toughness, degradability, and recyclability of carbon fiber reinforced composite materials herein we synthesized modified nano lignin polyols using alkali lignin as a raw material. The successful synthesis of nano lignin polyols was confirmed through dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR). Subsequently, nano lignin polyol particles were incorporated into the matrix to fabricate a nano lignin polyol-based epoxy resin matrix. Consequently, carbon fiber reinforced nano lignin polyol epoxy resin matrix composite (NFRP) were prepared via vacuum impregnation followed by closed mould sealing and cooling detachment. The results demonstrated that, in comparison with the carbon fiber reinforced composite material (LFRP) prepared using the original lignin-based epoxy resin, NFRP exhibited a remarkable increase of 104.66% in flexural strength and a significant enhancement of 65.23% in flexural modulus, reaching an impressive value of 11.3 GPa. Moreover, the interlayer shear strength (ILSS) reached an exceptional level of 91.17 MPa, surpassing the standard carbon fiber composite materials available on the market. Additionally, NFRP displayed an outstanding tensile strength of 2337.50 MPa, expanding the application range of carbon fiber reinforced composite materials while reducing material damage rates and increasing their service life span. Notably, NFRP achieved an impact toughness value as high as 142.60 kJ/m2, which is equivalent to 184% of popular epoxy resin matrix EFRP found on the market today. These findings provide novel insights and methodologies for applications requiring higher toughness and strength requirements in composite materials while also paving new avenues for degradable recovery approaches for carbon fiber reinforced composite materials.