A method for preparing epoxy-cellulose nanofiber composites with an oriented structure

Abstract A method was developed for processing cellulose nanocomposites using conventional vacuum infusion. Porous cellulose nanofiber networks were prepared via ice-templating and used as preforms for impregnation with a bio-epoxy resin. Microscopy studies showed a unidirectionally oriented micrometer-scale pore structure that facilitated the infusion process by providing flow channels for the resin. The permeability of the preforms was comparable to that of natural fiber mats, and the infusion time significantly decreased after optimizing the processing temperature. The flexural modulus of the bio-epoxy increased from 2.5 to 4.4 GPa, the strength increased from 89 to 107 MPa, and the storage modulus increased from 2.8 to 4.2 GPa with 13 vol% cellulose nanofibers. The mechanical properties also showed anisotropy, as the flexural and storage moduli were approximately 25% higher in the longitudinal direction, indicating that the nanofiber network inside the epoxy matrix had an oriented nature