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This paper concerns the rheological behavior of carboxymethylcelulloses(CMC) derived after one and two successive steps from different non-woodbleached cellulose pulps. CMC rheological characterization was achieved in0.1M NaCl solution, as a function of polymer concentration. Theevidence of a critical concentration (C* < 1 g/L) is discussedfromsteady shear and dynamic experiments. Rheological properties...
The opportunities provided by rheo-optical techniques for the investigation of cellulose derivatives in solution are discussed. Flow birefringence experiments yield information on the optical properties of the material and allow to distinguish between the contribution of different structural elements like, for example, the dangling chains and the anisotropic stem of fringed micelles on shear thinning...
Investigation of the dissolution of cellulose in Ethylene Diamine (EDA)/Potassium thiocyanate (KSCN) solutions by infrared spectroscopy (FTIR) and thermal analysis (DSC) indicated that changes to the solvent during freeze thaw cycling of mixtures was consistent with increased interaction between cellulose and solvent. Thermal transitions in the system, however, occurred at temperatures outside the...
The chiroptical properties and transient rheological behavior of (acetyl)(ethyl)cellulose (AEC) m-cresol liquid crystalline solutions have been investigated. Chiroptical properties were manipulated through (i) increasing degree of acetylation of ethyl cellulose (EC), and (ii) blending AEC with EC. At the same average degree of acetylation (DA), the chiroptical properties of pure AEC were different...
Interaction between tamarind seed xyloglucan and the other polysaccharides, gellan gum or xanthan investigated by rheology, differential scanning calorimetry, and related methods was discussed. All these three polysaccharides do not form a gel at lower concentrations by itself at the experimental conditions studied but the gelation of xyloglucan occurs in the presence of gellan or xanthan. Gelation...
Biocompatible nanofibers that are capable of adapting to the physiological conditions of the human body have become increasingly important for clinical applications in recent years. Electrospun fiber mats offer particular advantages due to their large surface area and their sorption/release properties. If loaded with drugs, delivery properties can be tailored to a specific release rate. This research...
Structure and properties for binary blends composed of biomass-based cellulose acetate propionate (CAP) and poly(epichlorohydrin) (PECH) have been studied. It is found from the dynamic mechanical measurements that mutual dissolution takes place to some degree with remaining CAP-rich and PECH-rich regions in the blends. As a result of the interdiffusion, leading to fine morphology, the blends exhibit...
The rheology of cellulose microfibril suspensions from TEMPO-oxidized pulp was investigated. The suspension showed a pseudo-plastic and thixotropic behavior, slowly evolving with time under a given shear rate. The viscosity was proportional to the concentration up to the critical concentration of 0.23%. Above it, the viscosity followed a power law with exponents from 2 to 6 depending on the shear...
Cellulose films were successfully prepared from NaOH/urea/zincate aqueous solution pre-cooled to −13 °C by coagulating with 5% H2SO4. The cellulose solution and regenerated cellulose films were characterized with dynamic rheology, ultraviolet–visible spectroscope, scanning electron microscopy, wide angle X-ray diffraction, Fourier transform infrared (FT-IR) spectrometer, thermogravimetry and tensile...
The influence of ZnO as cellulose-8%NaOH-water solution stabilizer against gelation is studied. Cellulose intrinsic viscosity in 8%NaOH-water as a function of solution temperature is investigated in the presence and absence of ZnO. The addition of ZnO did not bring any improvement in terms of solvent thermodynamic quality. Non-dissolved ZnO particles were observed above 0.8–0.9% ZnO in 8%NaOH-water...
Polymer nanocomposites were prepared from poly(oxyethylene) PEO as the matrix and high aspect ratio cellulose whiskers as the reinforcing phase. Nanocomposite films were obtained either by extrusion or by casting/evaporation process. Resulting films were characterized using microscopies, differential scanning calorimetry, thermogravimetry and mechanical and rheological analyses. A thermal stabilization...
Using two cationic methacrylate polymers: poly([2-(methacryloyloxy)ethyl] trimethyl ammonium iodide) (PDMQ) and poly[(stearyl methacrylate)-stat-([2-(methacryloyloxy)ethyl] trimethyl ammonium iodide)] (PSMA13Q), we modified microfibrillated cellulose (MFC) water suspensions. The aim was to affect the flocculation and rheological behavior of the MFC suspension. PDMQ is a strongly cationic polymer while...
Alkaline solutions of cellulose and polyethylene-co-acrylic acid (PE-co-AA) were mixed in order to prepare homogeneous cellulose/PE-co-AA blends. Different mixing methods were tested and the evolution of solutions was characterized by rheological methods and optical microscopy. In addition to the solution stage studies, the precipitated dry blends were characterized by Differential Scanning Calorimetry,...
The hypothesis advanced in this issue of CELLULOSE [Springer] by Bjorn Lindman, which asserts that the solubility or insolubility characteristics of cellulose are significantly based upon amphiphilic and hydrophobic molecular interactions, is debated by cellulose scientists with a wide range of experiences representing a variety of scientific disciplines. The hypothesis is based on the consideration...
Our aim was to characterise the suspension rheology of microfibrillated cellulose (MFC) in relation to flocculation of the cellulose fibrils. Measurements were carried out using a rotational rheometer and a transparent cylindrical measuring system that allows combining visual information to rheological parameters. The photographs were analyzed for their floc size distribution. Conclusions were drawn...
Cellulose acetate (CA) solutions have been shown to undergo phase-separation-induced gelation upon the addition of polar nonsolvents involving both hydrogen bonding and hydrophobic interactions. Using cellulose acetates with specific regiochemistry, only free hydroxyl groups at the C6 position of the anhydroglucopyranose unit, the viscoelastic behaviour and gel properties were evaluated. Steady-state...
In this work, the rheological properties of microfibrillated cellulose suspensions under stepped flow and constant shear were studied using a combination of rotational dynamic rheometer and digital imaging. During each rheological measurement, the structure of the suspension was monitored through a transparent outer cylinder with a digital camera. This enabled simultaneous analysis of the suspension...
Chemical pretreatment combined with high-intensity ultrasonication was performed to disintegrate cellulose nanofibers from poplar wood powders. The cellulose content in each suspension was treated as the control variable because the suspension concentration significantly influences the properties of the resultant cellulose nanofibers via ultrasonic processing. The as-obtained cellulose nanofibers...
This work deals with the selective incorporation of reactive isocyanate groups into methyl cellulose in order to be used as reactive thickening agent in castor oil. Resulting gel-like dispersions may have potential applications as green lubricating greases formulated from renewable resources. Two different isocyanate-functionalized methyl cellulose-based polymers were obtained by reaction of methyl...
Microfibrillated Cellulose (MFC) was isolated from unbleached kraft pulp derived from kenaf bast fiber. MFC gels with different concentrations were manufactured from pulp with varying initial consistencies. The MFC was diluted to a consistency of around one percent using distilled water and was further homogenized by passing through a microfluidizer. In order to gain an understanding of the relative...
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