AbstractThermoplastic epoxy resin (TPER)-based composites containing different amounts of ultra-fine cellulose (UFC) were prepared via melt compounding and injection molding. The effect of UFC loading on the mechanical properties and dynamic rheological behavior of the UFC-filled TPER composites was analyzed. The UFC-filled composites displayed higher complex viscosities than those of the neat TPER composites, especially at low frequencies. The elastic modulus of the 20 wt.% UFC-filled composite was up to 6- and 2-fold higher than that of TPER at 0.1 and 100 Hz, respectively. The loss factor decreased over the entire frequency range with the incorporation of UFC. The tensile modulus of elasticity (TMOE) of neat TPER was 3.13 GPa, and it increased as a function of UFC loading. The neat TPER exhibited the lowest flexural strength (108.1 MPa), and the flexural strength increased by 14% with the incorporation of 20 wt.% UFC. The results of the TMOE and the flexural modulus of elasticity (FMOE) were in agreement with rheological data on complex viscosity, elastic modulus, and viscous modulus. Ultra-fine cellulose-filled TPER composites may provide special capabilities for automotive applications and may also meet requirements for end-of-life vehicle (ELV) directives.