Abstract. Three techniques including acid hydrolysis (AH), 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation (TMO) and ultrasonication (US) were introduced to isolate nanocellulose from microcrystalline cellulose, in order to reinforce poly(vinyl alcohol) (PVA) films. Important differences were noticed in fiber quality of nanocellulose and film properties of PVA nanocomposite films. The TMO treatment was more efficient in nanocellulose isolation with higher aspect ratio, surface charge (-47 mV) and yields (37%). While AH treatment resulted in higher crystallinity index (88.1%) and better size dispersion. The fracture surface, thermal behavior and mechanical properties of the PVA nanocomposite films were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile testing. The results showed that both the TMO-derived and AH-derived nanocellulose could be dispersed homogeneously in the PVA matrices. AH/PVA films had higher elongation at break (51.59% at 6 wt% nanocellulose loading) as compared with TMO/PVA, while TMO/PVA films shown superior tensile modulus and strength with increments of 21.5% and 10.2% at 6wt% nanocellulose loading. The thermal behavior of the PVA nanocomposite films was higher improved with TMO-derived nanofibrils addition.
3-Methacryloxypropyltrimethoxysilane (MEMO) was used to modify the surface of cellulose nanofibrils (CNF) to improve the interfacial adhesion between the hydrophilic CNF and the hydrophobic poly(lactic acid) (PLA). MEMO modified CNF (M-CNF) were characterized by means of Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and atomic force microscope (AFM). Testing thin films with good transparency were obtained by casting the DMAC solutions of the composites onto glass plates and evaporating the solvent at 80 C. PLA/M-CNF composites were tested by tensile testing, scanning electron microscope (SEM), and AFM. The effect of MEMO and CNF on performance of PLA was investigated. The FTIR analysis successfully showed that coupling reaction has been successfully occurred and the hydroxyl groups of MEMO are strongly hydrogen bonded to that of CNF. The thermal stability of M-CNF was little decreased. The M-CNF kept their morphological integrity. The highest tensile strength of composites was obtained for PLA with 1.0% v/v MEMO and 1.0 wt % CNF. M-CNF disperse well and cross with each other in the PLA matrix.
A new nanocrystalline cellulose/polysulfone composite membrane was prepared. The composite membranes were coagulated in different coagulation baths (i.e., water, methanol, ethanol, isopropanol) and concentrations (i.e., 10, 30, 50 v/v %). The chemical structure of membrane is characterized by Fourier transform infrared spectroscopy. The viscosity of the casting solutions was measured. The cross-section morphology of the membrane was characterized using scanning electron microscopy. The mechanical properties were also studied. Results showed that the connectivity of nanocrystalline/polysulfone composite membrane pores is better than that of pure polysulfone membrane, macrovoids, and short finger-like pores are produced when adding methanol, ethanol, or isopropanol into the coagulation bath. As the coagulant concentration increases, the sponge-like structure becomes looser and thinner. A right amount of nanocrystalline cellulose has a positive effect on the tensile strength. The tensile strength of the pure membrane in different coagulation baths shows the following order: methanol > ethanol > isopropanol > water (10 % v/v). C 2014 Wiley Periodicals, Inc. Adv Polym Technol 2015, 34, 21471; View this article online at wileyonlinelibrary.com.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.