Properties Of Cellulose Acetate Research Articles

Effect of aeration rate on the anti-biofouling properties of cellulose acetate nanocomposite membranes in a membrane bioreactor system for the treatment of pharmaceutical wastewater

In this study, the effect of aeration rate in terms of specific aeration demand per membrane area (SADm) on the anti-biofouling properties of cellulose acetate (CA) nanocomposite membranes (CA/ND-NH2) in a membrane bioreactor system was investigated. The amount of EPS and soluble EPS under high aeration rate conditions was observed to be higher than under low aeration rate conditions. The results obtained showed that either lower or higher aeration rates had a negative impact on membrane permeability. The high aeration rate resulted in a severe breakage of sludge flocs, and promoted the release of soluble EPS from the microbial flocs to the bioreactor tank. By increasing the aeration rate, the COD removal increased and decreased respectively for the membranes and the activated sludge. It was finally concluded that higher anti-biofouling properties of neat CA and nanocomposite membranes were obtained under optimal aeration rate conditions (SADm = 1 m3 m−2 h−1).

Synthesis, Characterization and dye absorbing properties of cellulose acetate from used cigarette buds

Abstract Water pollution is a great threat to humanity nowadays. Scientists are searching for new natural materials that can act as absorbents to remove non-biodegradable pollutants. Dye waste from textile, paint and leather industries are a great danger to aquatic system. Nowadays activated charcoal is widely used for this purpose, but the high cost impose some limitations to its wide use. Cellulose acetate was synthesized from a waste material, used cigarette bud, by acid treatment method. The sample obtained was characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Cellulose acetate membranes were prepared and utilized for dye absorption studies using UV-visible spectroscopy and colorimeter using pH controlled solutions of methylene blue and malachite green.

셀룰로스 나노휘스커 강화 셀룰로스 아세테이트 복합재료의 특성

셀룰로스 나노휘스커 강화 셀룰로스 아세테이트 복합재료의 특성

Cellulose acetate blends with acrylonitrile/N-phenyl maleimide copolymers morphological and thermal properties

Cellulose acetate (CA) was blended in different compositions with various acrylonitrile-N-halo phenyl maleimide (AN-XPhM) copolymers to improve the thermal and mechanical properties of cellulose acetate. The structure, morphology, thermal stability, and crystallinity of the blend films were characterized by infrared spectroscopy, scanning electron micrographs, thermogravimetry/differential thermal analysis, differential scanning calorimetry, and X-ray diffraction. The results revealed that the thermal stability was improved by the increase in AN-XPhM content, irrespective of the type of the N-halo phenyl maleimide. The CA/AN-4BrPhM blend films possessed the highest thermal stability compared to the other CA/AN-XPhM blend films. Blending CA with AN-4BrPhM yielded the most homogeneous blend films, irrespective of the composition ratio. The mechanical properties of various compositions of the CA/AN-4BrPhM blend films were also discussed.

Thermal decomposition of mercerized linter cellulose and its acetates obtained from a homogeneous reaction

Cellulose acetates with different degrees of substitution (DS, from 0.6 to 1.9) were prepared from previously mercerized linter cellulose, in a homogeneous medium, using N,N-dimethylacetamide/lithium chloride as a solvent system. The influence of different degrees of substitution on the properties of cellulose acetates was investigated using thermogravimetric analyses (TGA). Quantitative methods were applied to the thermogravimetric curves in order to determine the apparent activation energy (Ea) related to the thermal decomposition of untreated and mercerized celluloses and cellulose acetates. Ea values were calculated using Broido's method and considering dynamic conditions. Ea values of 158 and 187 kJ mol-1 were obtained for untreated and mercerized cellulose, respectively. A previous study showed that C6OH is the most reactive site for acetylation, probably due to the steric hindrance of C2 and C3. The C6OH takes part in the first step of cellulose decomposition, leading to the formation of levoglucosan and, when it is changed to C6OCOCH3, the results indicate that the mechanism of thermal decomposition changes to one with a lower Ea. A linear correlation between Ea and the DS of the acetates prepared in the present work was identified.

Influence of the Substitution Degree on the Dilute Solution Properties of Cellulose Acetate

Modification of intrinsic viscosity, coil size, and preferential adsorption coefficients of cellulose acetate with various substitution degrees in single and mixed solvents was investigated at different temperatures. Miscibility is attained by specific competitive interactions between the solvent-solvent and solvent-polymer systems, which induce modification in the composition of solvent mixtures both inside and outside the polymer coil. The conformational properties in solutions were correlated with the preferential adsorption coefficients, known as depending on the interaction parameters of the polymer/solvent/solvent systems. The intermolecular interactions observed in the cellulose acetate solutions assure the main properties necessary for obtaining membranes with different applications.

Influence of the dilute‐solution properties of cellulose acetate in solvent mixtures on the morphology and pervaporation performance of their membranes

AbstractThe pervaporation performance of cellulose acetate (CA) membranes prepared from acetone (AC), acetone/tetrahydrofuran (AC/THF), acetone/chloroform (AC/CF), and acetone/cyclohexane (AC/CYH) was studied for separating MeOH/MTBE (methyl tert‐butyl ether) mixture with 5 (wt) % MeOH. The dilute‐solution properties and Huggins constant (KH) of CA dissolved in AC and AC/solvent mixtures with 15 vol % of the second solvent (tetrahydrofuran, chloroform, or cyclohexane) were examined. J and α of the CA membranes were affected by the types of solvent mixtures used to prepare the casting solutions. Under the same conditions, the membrane with AC/CYH had the highest J value and the lowest α value, and it was followed by the membranes with AC/CF, AC/THF, and AC. The increasing value of J and decreasing value of α for the CA membranes from different solvent mixtures were in good agreement with the increasing value of KH of CA in corresponding solvent mixtures. Furthermore, differences in the morphology from scanning electron microscopy images of the cross sections or from atomic force microscopy photographs of the surfaces of the membranes existed, and they provided proof of the different pervaporation performances of the CA membranes prepared from AC and AC/solvent mixtures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97:1891–1898, 2005

Study of the Sorption Properties of Cellulose Acetate Modified with Aluminon and Eriochrome Cyanine R

Study of the Sorption Properties of Cellulose Acetate Modified with Aluminon and Eriochrome Cyanine R

Application of instrumental methods for rapid analysis of physicochemical properties of cellulose acetates and solutions of them

Comparative data make it possible to recommend the method of turbidimetric titration for determining molecular weight distribution of cellulose acetates to central plant laboratories as an input control index in the process of processing them.

Effect of additions of oligomeric epoxides on the physicochemical properties of cellulose acetates

The effect of oligomeric epoxides based on polyethylene oxide and epichlorohydrin, having an epoxy group content of 8–15%, on the physicochemical and structural—mechanical properties of solutions and films of CA has been described.

Properties of cellulose acetate. III. Light scattering from concentrated solutions and films. Tensile creep and desalination studies on films

AbstractLight scattering from concentrated solutions of cellulose acetate in acetone is discussed in terms of exponential correlation functions for refractive‐index fluctuations. These are related to intermolecular aggregation. Light scattering, tensile creep and recovery, and hyperfiltration studies with films of cellulose acetate cast from acetone are discussed in terms of the state of aggregation in the films. It is concluded that intermolecular aggregates are probably small and imperfectly formed regions of microcrystallinity stable up to about 210°C, with the overall state one of near amorphous disorder.

Properties of cellulose acetate in solution. II. Light scattering and elasticity measurements on gels in benzyl alcohol

AbstractKinetic studies are reported for the light scattering and elasticity of thermally reversible gels of cellulose acetate in benzyl alcohol over a range of temperature and polymer concentration. The small‐angle light scattering data are found to be described by exponential correlation functions, and it is concluded that the scattering has its origin in the nonrandom character of the crosslinking in the gels studied. The elasticity is discussed in terms of the density of crosslinks in the gels. Thus, the kinetics studied by light scattering and elasticity measurements are independently related to temperature and polymer concentration.

Properties of cellulose acetate in solution. I. Light scattering, osmometry, and viscometry on dilute solutions

AbstractLight‐scattering, osmotic pressure, and viscometric studies on fractions of cellulose acetate (degree of substitution 2.45) in three solvents are described. The data yield the dependence of the mean‐square radius of gyration 〈s2〉, the second virial coefficient Γ2, and the intrinsic viscosity [η] on molecular weight M and temperature. The results are interpreted to show that excluded volume effects on 〈s2〉 are negligible, even though Γ2 is large and dΓ2/dT is positive. The large experimental value of d In [η]/d In M is interpreted in terms of partial draining effects. Data on 〈s2〉 and [η] for other cellulose esters in the literature are similarly interpreted. Significant aggregation found in solutions of cellulose acetate in many solvents is discussed.

Manufacture and Properties of Cellulose Acetate

Manufacture and Properties of Cellulose Acetate

Gel-penetrating chromatography method of investigating the influence of the preparation conditions on the molecular weight distribution and properties of cellulose acetate

Gel-penetrating chromatography method of investigating the influence of the preparation conditions on the molecular weight distribution and properties of cellulose acetate

On the nature and properties of cellulose acetate and poly(vinyl alcohol) gels

AbstractDilatometric, rheological, and some optical (spectrography, birefringence, light scattering) investigation methods were adopted to study gelation processes in acetyl cellulose (AC), poly(vinyl alcohol) (PVA), and iodopoly(vinyl alcohol) (IPVA) solutions in different solvents. The influence of the molecular and chemical heterogeneity of these polymers upon the gelation temperature and mechanical properties of gels is ascertained. The jumps in the volume versus temperature dependence ΔV(T) of PVA fraction solutions were discovered. The greater the molecular weight of polymer fractions the higher is the temperature of these jumps. It is established that diluted AC solutions in benzyl alcohol as well as its concentrated acetone solutions are nonhomogeneous thixotropic systems with long relaxation times. The results of investigation have been interpreted by means of the conception about gelation as the separation of fractions, which have become insoluble (under changed thermodynamic conditions), from homogeneous polymer solution. These fractions form a second amorphous phase, either as the single whole network, enveloping the solution of the other fractions by its network (gel), or as discrete aggregates (gel suspension). The structure variants, for example, partial crystallization, present the consecutive stages of a thermodynamic transition of a true solution into a non‐homogeneous colloid system.

Factors affecting the solution properties of cellulose acetate

AbstractAbsorbance measurements on concentrated solutions of cellulose 2 1/2‐acetates in acetone show that the apparent absorbance is almost entirely due to turbidity. The size of the scattering particles is comparable with the wavelength of light. Sedimentable fractions are responsible for the anomalous viscosity of concentrated solutions of cellulose acetates as well as for their turbidity. These sedimentable fractions are enriched in xylan and mannan acetate. Solubility differences found for sediments rich in either xylan or mannan acetate, and extraction experiments with polar and nonpolar solvents revealed that more polar impurities, such as xylan acetates, are responsible for turbidity, while less polar impurities, such as mannan acetates, are responsible for false viscosity. A hypothesis based on solvent interaction and polymer incompatibility has been advanced to coordinate these and earlier findings.

Amination of Cellulose Acetate Chloroacetate. Preparation and Properties of Cellulose Acetate N,N-Diethylaminoacetate

Amination of Cellulose Acetate Chloroacetate. Preparation and Properties of Cellulose Acetate N,N-Diethylaminoacetate

Applications of Trifluoroacetic Anhydride in Carbohydrate Chemistry

This chapter discusses the applications of trifluoroacetic anhydride in carbohydrate chemistry. Trifluoroacetic anhydride is concerned with an attempt to prepare cellulose trifluoroacetates by the direct treatment of cellulose with the anhydride. No reaction is apparent, but when the cellulose is pretreated with acetic acid, it subsequently dissolved slowly in trifluoroacetic anhydride, with the formation of a chloroform-soluble product containing no fluorine and having the properties of cellulose acetate. Trifluoroacetic anhydride is conveniently prepared in high yield by the distillation of trifluoroacetic acid over phosphorus pentoxide. An alternative procedure utilizes sulfur trioxide to convert trifluoroacetic acid into trifluoroacetylsulfuric acid, which on further treatment with trifluoroacetic acid affords trifluoroacetic anhydride.

繊維素エステルのコロイド性の研究(第一報)成熟作用の酷酸繊維素物理的性質に及ぼす影響

繊維素エステルのコロイド性の研究(第一報)成熟作用の酷酸繊維素物理的性質に及ぼす影響