title: Preparation of nanocrystalline cellulose via ultrasound and its reinforcement capability for poly(vinyl alcohol) composites.
abstract: Rod-shaped nanocrystalline cellulose (NCC) was prepared from microcrystalline cellulose (MCC) using the purely physical method of high-intensity ultrasonication. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction was used for the characterization of the morphology and crystal structure of the material. The thermal properties were investigated using thermogravimetric analysis. The reinforcement capabilities of the obtained NCC were investigated by adding it to poly(vinyl alcohol) (PVA) via the solution casting method. The results revealed that the prepared NCC had a rod-shaped structure, with diameters between 10 and 20 nm and lengths between 50 and 250 nm. X-ray diffraction results indicated that the NCC had the cellulose I crystal structure similar to that of MCC. The crystallinity of the NCC decreased with increasing ultrasonication time. The ultrasonic effect was non-selective, which means it can remove amorphous cellulose and crystalline cellulose. Because of the nanoscale size and large number of free-end chains, the NCC degraded at a slightly lower temperature, which resulted in increased char residue (9.6-16.1%), compared with that of the MCC (6.2%). The storage modulus of the nanocomposite films were significantly improved compared with that of pure PVA films. The modulus of PVA with 8 wt.% NCC was 2.40× larger than that of pure PVA.
authors.affiliation: College of Material Sciences and Engineering, Northeast Forestry University, Harbin 150040, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.forename: Jinquan
authors.initials: J
authors.lastname: Yue
authors.forename: Shouxin
authors.initials: S
authors.lastname: Liu
mesh_terms: D002482:Cellulose / Q000138:chemical synthesis* / Q000528:radiation effects*; D055119:Elastic Modulus / Q000528:radiation effects; D019220:High-Energy Shock Waves; D008420:Manufactured Materials / Q000032:analysis / Q000528:radiation effects; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D011142:Polyvinyl Alcohol / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D013010:Sonication / Q000379:methods*; D013814:Thermal Conductivity
chemical_list: D011142:Polyvinyl Alcohol; D002482:Cellulose