Enhanced properties of poly(ethylene oxide)/cellulose nanofiber biocomposites

Poly(ethylene oxide) (PEO)/cellulose nanofiber (CNF) biocomposites were developed using a simple aqueous solution technique. A PEO/CNF composite was also produced in the molten state to compare different preparations. The effects of nanofibers on different properties of PEO including rheological, thermal, mechanical and optical were investigated. For the sample prepared in the molten state, no change in properties was observed as compared to the neat matrix. On the other hand, for the solution-based samples, scanning electron microscopy revealed good dispersion/distribution of nanofibers in the PEO, which resulted in a significant increase of the rheological properties and also a notable shear-thinning behavior. A liquid- to solid-like behavior transition along with the observation of apparent yield stress suggested the formation of a strong CNF 3D network. The Young's modulus and tensile strength of PEO with 3 wt% CNFs were enhanced by 49 and 35%, respectively, compared to the neat PEO. The storage modulus of PEO was significantly improved for all tested temperatures in the dynamic mechanical thermal analysis; at room temperature that corresponds to the rubbery region, a 47% enhancement was observed by incorporating 3 wt% nanofibers. Also, PEO/CNF composites demonstrated good optical transmittance, which is generally not the case with many reinforcements. These results show that PEO/CNF biocomposites with good mechanical and optical properties can be fabricated via a simple aqueous solution technique.