Solubility Of Cellulose Acetate Research Articles

Preparation and Characterization of Cellulose Derivatives from Agricultural Wastes

Background: Rice straw was pretreated with dilute alkaline and acid solutions to extract cellulose, which was then converted into cellulose acetate with acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The concentration of KOH and the duration of immersion in acetic acid solution affected the removal of hemicellulose and lignin, and after pretreatment with 4% KOH and immersion in acetic acid for 5 hours, the treated rice straw contained 83wt.% cellulose. Phosphotungstic acid has been shown to be an excellent catalyst for the acetylation of rice straw cellulose. The degree of substitution (DS) values had a substantial effect on the solubility of cellulose acetate, and acetone-soluble cellulose acetate with DS values about 2.2 can be generated by varying the amount of phosphotungstic acid and acetylation duration. Objectives: The aim of the study was to evaluate the preparation and characterization of cellulose derivatives from agricultural wastes. Methods: This cross-sectional study was carried out in the Department of Communicable Diseases Control, Director General of Health Services, Dhaka, Bangladesh. For this investigation the rice plant straw was collected from Magura district region. The collected straws were then treated with 3 wt% nitric acid and 1.5 wt% NaOH solution separately. Statistical analyses of the results were be obtained by using window-based Microsoft Excel and Statistical Packages for Social Sciences (SPSS-24). Results: This study observed that the rice straw contained about 35.67% cellulose, 5.50% hemicellulose and 30.18 % α-cellulose. And the wheat straw contained about 43.99% cellulose, 7.30% hemicellulose and 36.70% α-cellulose. The degree of acetylation and degree of substitution of the synthesized cellulose acetate from rice straw were 39.046% and 2.413 respectively. On the other hand, the degree of acetylation and degree of substitution of the synthesized cellulose acetate from wheat straw were 40.79% and 2.59 respectively. ....

Understanding solubility, spinnability and electrospinning behaviour of cellulose acetate using different solvent systems

The purpose of this study is to understand the solubility and spinnability of cellulose acetate (CA) and its electrospinning behaviour in different solvents. As the process of electrospinning and the corresponding fibre properties are primarily governed by the solvents used, a systematic study of the selection of solvent systems using the solubility parameters of Hildebrand and Hansen along with a Teas chart for a particular polymer is essential for the better optimization of the process. It appeared from the Teas chart that higher dispersion force \((f_{\mathrm{d}})\) and lower hydrogen bonding force \((f_{\mathrm{h}})\) are convenient for both the solubility and spinnability of CA in single solvent of acetone and binary solvent of 2:1 acetone/N,N-dimethylacetamide (DMAc). The viscosity of the solutions escalated with increasing concentration of CA due to polymer chain entanglement which in turn favoured fibre formation. Among the solvent systems used in this work, field emission scanning electron microscopy arrayed the electrospun CA fibres using pure acetone as a solvent produced both cylindrical- and ribbon-shaped fibres of a diameter of 1 \(\upmu \)m, whereas CA in 2:1 acetone/DMAc yielded smooth bead-free cylindrical fibres of diameter in the range of 250–350 nm and CA in 3:1 acetic acid/water formed fibres with beads. Rheological analysis showed that fibre formation improved with increasing viscosity of CA solution. Electrical conductivity measurement of the CA solutions depicted that with an increase in CA concentration, fibre diameters were increased, whereas the conductivity decreased. Also, attenuated total reflectance–Fourier transform infrared spectroscopy confirmed the major peaks of CA for all the electrospun samples.

NMR characterization of cellulose acetate: Mole fraction of monomers in cellulose acetate determined from carbonyl carbon resonances

Cellulose acetate (CA) samples with varying degrees of substitution were prepared via homogeneous acetylation in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and by the acid-hydrolysis of cellulose triacetate in acetic acid. Quantitative analysis of the 13C NMR spectra facilitated the assignment of the carbonyl carbon shifts of the 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, 3,6-di-, and 2,3,6-tri-substituted anhydroglucose units (AGUs), and the determination of the mole fraction of 7 AGUs and unsubstituted AGU in the CA chains. This shed some light on the mechanism of CA production in homogeneous reaction systems. In addition, comparison of the mole fractions of the 8 AGUs suggested that the acetone solubility of CA strongly related to the AGU composition.

The swelling and solubility of cellulose acetate in benzene/xylenol mixtures

Mixtures of benzene/xylenol gelled by cellulose acetate were much used as incendiary materials, and the present study of these systems was undertaken to elucidate the problem of syneresis on storage. This involved a study of the phase behaviour of the commercial cellulose acetate (heterogeneous both as regards chain length and acetyl number), in binary mixtures of xylenol (solvent) and benzene (non-solvent). A fixed concentration (4 % by weight) of cellulose acetate in various benzene/xylenol mixtures ranging from pure benzene to 17% xylenol (by weight) was used, and the composition of the liquid and swollen phases in equilibrium found by analysis after centrifuging. The cellulose acetate in each phase was characterized by both chain length and acetyl content. In this way it was shown that the commercial cellulose acetate contained three major fractions, which differed but little in average chain length, but to a great extent in acetyl content. The three major fractions were then separated in sufficient quantity to enable their separate phase behaviour to be determined. It was found that the solubility of any one fraction was affected by the presence of the others, and an explanation for this has been advanced.