Poly(lactic acid) (PLA) biocomposites are usually plasticized to overcome the problem of poor ductility, which decreases the valuable tensile strength. In this study, novel nanofibrillated cellulose (NFC) was extracted to enhance the acetyl tributyl citrate (ATBC) plasticized PLA biocomposites. Interestingly, NFC not only exhibited an excellent strengthening effect but also showed a further toughening effect in the biocomposites. When 4 wt% NFC was added, the tensile strength, elongation at break, and impact strength of the biocomposites with 15 wt% ATBC and 20 wt% ATBC reached 52.6 MPa, 28.4%, 34.9 J/m and 35.8 MPa, 300.1%, 40 J/m, respectively. This is at least 1.1 folds higher in strength and 2.3 folds higher in impact toughness than the biocomposites without NFC. Glass transition and melting temperature slightly increased with NFC addition. More importantly, the mechanism of the strengthening and toughening effect was definitely elucidated, and the comprehensive performance of the application was evaluated. The findings of the study provide significant guidance for PLA application, such as in food packaging, medical engineering materials, and household products.

Poly (butylene adipate-co-terephthalate) (PBAT) is a fully biodegradable polymer with toughness and ductility. It is usually compounded with thermoplastic starch (TPS) to balance the cost for manufacturing biodegradable films such as disposable plastic bags. However, blending with TPS reduces valuable tensile strength, which limits the bearing capacity of PBAT film. In this study, microcrystalline cellulose (MCC) was employed as a reinforcement to strengthen the PBAT/TPS biodegradable film. The effect of MCC content on the mechanical, thermal, and morphological properties of the composite film were investigated. The optimal tensile strength and elongation at break reached 5.08 MPa and 230% when 4% MCC was added. The thermal stability and thermal resistance were improved with the addition of MCC; for example, T_max increased by 1 °C and T_onset increased by 2–8 °C. Moreover, good compatibility among PBAT, TPS, and MCC can be achieved when the MCC content was below 6%. Consequently, the optimal MCC content was found to be 4%. These results could provide experimental data and method support for preparing high-performance PBAT hybrid films.