Mechanical, morphological, and thermal characteristics of epoxy/glass fiber/cellulose nanofiber hybrid composites

Generally, glass fiber-reinforced polymer composites are made in the form of laminated composites. Due to the weak adhesion between the fiber and the polymer matrix, failure in the form of delamination often occurs. To overcome delamination, the incorporation of very low content of nanomaterials has been considered. The effect of cellulose nanofibers (CNFs) addition on the mechanical, morphological, and thermal properties of the epoxy/glass fiber/CNFs hybrid composites was evaluated. The hybrid composites containing 1 and 2 wt% CNFs were prepared by hand lay-up followed by vacuum bagging and compression. The mechanical characteristics of the composites were investigated through tensile, flexural, short beam shear, and impact tests, while thermal stability was evaluated by thermogravimetric analysis (TGA). The results revealed that with the presence of 1 wt% CNF, the tensile strength and modulus of the epoxy/glass fiber composites were enhanced by 9 and 10%, respectively whereas the flexural strength and modulus were increased by 16 and 6%, respectively. SEM observations showed the presence of a strong CNF interaction with glass fiber and a thin layer of epoxy interphase around the glass fibers. Moreover, the introduction of 1 wt% CNF to the epoxy/glass fiber composite improved the interlaminar shear strength by 11%, while the thermal stability did not change.