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We have succeeded in isolating nanostructures from never-dried cellulose wood pulp, in sheet-form that have sub-microfibril dimensions (single to double digit Å thickness with 100’s of nm in length). A recently developed oxidation procedure by Saito and co-workers (Biomacromolecules 2006, 7:1687–1691) combined with extensive ultrasonication was used to liberate nanoscale cellulose fibrils. We show...
The research herewith aims at obtaining cellulose nanocrystals with a reduced hydrophilic surface character using a silane with isocyanate groups (isocyanatepropyltriethoxysilane), which are very reactive to hydroxyl groups and thus, are readily able to react with the low quantity of free hydroxyl groups present in the cellulose nanocrystal surfaces, therefore, promoting surface modification. Cellulose...
Hydrophobic cellulose nanocrystals (CNs) have been prepared by grafting isocyanate-terminated castor oil, a kind of natural vegetable oil, onto their surface. The existence of castor oil component in the modified cellulose nanocrystals was verified by Fourier transform infrared spectroscopy, solid-state 13C NMR spectra and X-ray photoelectron spectroscopy. At the same time, X-ray diffraction and transmission...
The unique combinations of hard and soft components with core/shell structures were proposed to synthesize high strength nanocomposite hydrogels. The elastomeric hydrogels containing rod-like cellulose nanocrystals (CNCs) core and polyacrylamide shell were made from aqueous solutions via free radical polymerization in the absence of chemical cross-links. The obtained hydrogels possessed greater tensile...
A novel drug delivery system based on two of the most abundant natural biopolymers was developed by modifying the surface of oxidized cellulose nanocrystal (CNC) with chitosan oligosaccharide (CSOS). First, the primary alcohol moieties of CNC were selectively oxidized to carboxyl groups using the 2,2,6,6-tetramethylpiperidine-1-oxyl radical catalyst. The amino groups of CSOS were then reacted with...
The effect of drying method on selected material properties of nanocellulose was investigated. Samples of nanofibrillated cellulose (NFC) and cellulose nanocrystals (CNC) were each subjected to four separate drying methods: air-drying, freeze-drying, spray-drying, and supercritical-drying. The thermal stability and crystallinity of the dried nanocellulose were evaluated using thermogravimetric analysis...
Cellulose nanocrystals (CNCs) prepared from cellulose fibre via sulfuric acid hydrolysis was used as an adsorbent for the removal of methylene blue (MB) from aqueous solution. The effects of pH, adsorbent dosage, temperature, ionic strength, initial dye concentration were studied to optimize the conditions for the maximum adsorption of dye. Adsorption equilibrium data was fitted to both Langmuir and...
Bio-based continuous fibers were prepared by melt spinning cellulose acetate butyrate (CAB), cellulose nanocrystals (CNC) and triethyl citrate. A CNC organo-gel dispersion technique was used and the prepared materials (2 and 10 wt% CNC) were melt spun using a twin-screw micro-compounder and drawn to a ratio of 1.5. The microscopy studies showed that the addition of CNC in CAB resulted in defect-free...
Microfluidization, which is a high-pressure homogenization technique, was used to develop highly dispersed cellulose nanocrystal (CNC) reinforced chitosan based nanocomposite films. A three factor central composite design with five levels was designed to systematically optimize the microfluidization process. The three factors were the CNC content, the microfluidization pressure and the number of microfluidization...
The aim of this study is to design a nanocellulose based barrier film. For this purpose, cellulose nanofibrils (CNFs) are used as a matrix to create an entangled nanoporous network that is filled with two different nanofillers: nanoclay (reference), i.e. the mineral montmorillonite (MMT) and the bio-based TEMPO-oxidized cellulose nanocrystal (CNC-T), to produce different types of nanocelluloses...
Oriented films were prepared from aqueous suspensions of cellulose nanocrystal (CNC; microfibril fragment of sulfuric acid-hydrolyzed cotton) by a shearing method. Rotating glass vials each containing a 3–4 wt% CNC/water suspension under evaporation resulted in formation of translucent films of CNC per se. Structural characterization of the dry films was carried out by use of X-ray diffractometry...
Layers of cellulose nanocrystals are peeled off by controlled periodate and chlorite oxidation to produce nanocrystals with a tunable width. The chemical modification increases the solubility of the polymers at the crystal surface to the extent that they preferentially exist in solution and detach from the crystal. The number of layers removed is controlled by the degree of partial oxidation. The...
Lignin-coated cellulose nanocrystals (CNCs) were extracted from the tropical wood Angelim Vermelho in a yield of 47 % based on wood cellulose content. The procedure combined a mild steam explosion process with a treatment using 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). The resulting CNCs showed exceptional aspect ratios of 83 ± 18 for wood-based CNCs and crystallinity index of 76 %. Residual...
Rheo-optics, microspectrophotometry, and optical contrast measurements were used to gain new insights into the interrelated effects of liquid crystalline phase behavior, flow alignment, and microstructural relaxation on cellulose nanocrystal (CNC) films’ alignment and optical properties. Optical contrast measurements were found to be an effective and facile way of determining changes in anisotropy...
Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite suspensions increased with higher...
Polylactide (PLA) composites with pristine cellulose nanocrystals (CNC) and acetylated one (aCNC) were prepared for the crystallization study. The roles of CNC and aCNC in cold and melt crystallization of PLA were explored. Both CNC and aCNC have good nucleation activity during cold crystallization of PLA, but also highly impede transport of adjacent chain segments to the growing surface, acting as...
Electrospinning was used to fabricate bioactive nanofibrous membranes from cellulose nanocrystal-ZnO (CNC-ZnO) nanohybrids as reinforcing materials in biodegradable poly(3-hydroxybutyrate-co-3-hydroxy-valerate) (PHBV) for potential use as wound dressings. Incorporation of CNC-ZnO considerably improved the uniformity and reduced the diameter of PHBV nanofibers with porosity in the range of 14–56%....
Diabetic patients with foot ulcer showed 150-fold increased risk of amputation, which is primarily caused by microbial infection. Silver ions are commonly incorporated into wound dressing to enhance the antimicrobial property. However, concerns have been expressed about the development of bacterial resistance to heavy metals. In this study, we evaluate the in vitro and in vivo efficacy of cellulose...
To prepare liquid silicone rubber (LSR)/cellulose nanocrystal (CNC) nanocomposite, 3-aminopropyltriethoxysilane (APTES) was used to modify the surface of CNC to improve the interfacial interaction between the hydrophilic CNC and the hydrophobic LSR. Fourier transform infrared spectroscopy and energy dispersive spectrometer results demonstrated that APTES modified CNC successfully. It was found that...
This study focuses on the preparation and characterization of an iridescent chiral nematic cellulose nanocrystal (CNC) film in relation to their use as a humidity-responsive material. A free-standing film with Bragg reflection was successfully prepared. Thermogravimetric analysis demonstrated gradual thermal transitions with two major weight loss regions, while the crystallinity index obtained from...
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