Preparation of acetylated nanofibrillated cellulose from corn stalk microcrystalline cellulose and its reinforcing effect on starch films.

Acetylated nanofibrillated cellulose (ANFC) with different degrees of substitution (DS) was prepared from corn-stalk microcrystalline cellulose (MCC) using chemical-mechanical combined processes. The physicochemical properties of nanofibrillated cellulose (NFC) and ANFC were investigated together with the influence of added nanoparticles on the mechanical properties of starch films. The acetylation reaction was monitored by Fourier transform infrared (FT-IR) and titration. Particle size and morphological of NFC and ANFC were studied by atomic force microscope (AFM). The results suggested that NFC had nano-order-unit web-like network with mean diameter of ~24 nm. The thermostability of all samples was found to decrease as the modification extent rose, and mechanical disposal revealed no significant influence on the DS and crystalline structure of cellulose. The ANFC with the DS value of 0.35 demonstrated the best enhancement effect on starch films, with increased tension strength (TS) by 201%. The tensile tests confirmed that the web-like network structure of NFC was more conducive to strength, and proper chemical modification could improve the uniform dispersion of nano-fillers in starch to result in higher strength performances.