Surface modification of cellulose nanofiber using acid anhydride for poly(lactic acid) reinforcement

This research examined the performance of poly(lactic acid) (PLA) by the addition of cellulose nanofiber (CNF) as a filler. CNF produced by green fibrillation method without any chemical pre-treatment had advantages in low cost and time saving, which can produce bulky CNF in a short period compared with traditional methods such as acid dialysis and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidation. It was demonstrated that modification on the hydroxyl group of cellulose into acetyl group changed the compatibility of CNF with PLA. Acetylated cellulose nanofiber (ACNF) and PLA formed smooth surface composite films with good transparency and mechanical properties. Moreover, the tensile strength of neat PLA film was improved by 25% when 1 wt% of ACNF was used as the filler. Furthermore, without lowering the thermal stability of PLA, composite films of PLA/ACNF exhibited higher hydrophobicity as high as 85.9° compared with that of neat PLA film with 70.2° contact angle.