Reinforcing abilities of microfibers and nanofibrillated cellulose in poly(lactic acid) composites

The reinforcing abilities of cellulose microfibers and nanofibrillated cellulose (NFC) in poly(lactic acid) (PLA) were evaluated. NFC successfully prepared from regenerated cellulose fibers using high-speed blending for 60 min was introduced in a PLA matrix. The physical and mechanical properties of NFC-reinforced PLA composites were investigated in comparison with those of the composites with microfibers. NFC fibrils with diameters in the range of 100–500 nm were disintegrated from micron-sized regenerated fibers. A slight decrease in the degree of crystallinity and degradation temperature obtained for NFC after mechanical treatment was found compared with untreated microfibers. The introduction of NFC in the PLA effectively increased the tensile strength and Young’s modulus of the composites by 18% and 42%, respectively. The use of micron-sized fibers to reinforce PLA, on the other hand, showed a slight improvement in Young’s modulus (13%). The improvement in the mechanical properties of the composites reinforced with NFC was found because of the higher surface area of NFC and better interaction between the matrix and NFC fibrils. This allowed stress to transfer from the matrix to the reinforcement. NFC prepared using the high-speed blending could be an alternative to use as reinforcement in composites