Cellulose Xanthate Research Articles

Decomposition of cellulose xanthate in high-speed textile rayon spinning

Decomposition of cellulose xanthate in high-speed textile rayon spinning

Kinetics of cellulose xanthate precipitation studied with an MKU-2 microfilm camera

Kinetics of cellulose xanthate precipitation studied with an MKU-2 microfilm camera

The use of cellulose xanthate for the immobilisation of biological molecules

The mercapto groups of cellulose xanthate can reversibly form disulphide bridges with L-cysteine. This property has been utilised for the immobilisation of a protein and an enzyme. These macromolecules, as polythiol derivatives, formed disulphide linkages with the matrix without serious disturbance of their active sites, became firmly bound to the xanthate, and were not eluted by normal washing conditions. Cellulose xanthate is a cheap, easily prepared matrix which permits a simple coupling reaction. The immobilisation process is selectively reversible.

The xanthate method of grafting. II. Effect of operating conditions on the grafting of acrylonitrile onto Wood pulp

Wood pulp was copolymerized with acrylonitrile as a monomer using the xanthate grafting method. This method takes advantage of the capability of cellulose xanthates to form a redox couple with a suitable oxidation agent. The present work uses the degree of xanthation γ ≐ 5 and hydrogen peroxide as an oxidant. Experiments carried out under different conditions have permitted to evaluate the influence of various reaction parameters on the graft copolymerization. Among the factors investigated, two appeared to be a paramount importance: the initial pH of the reaction mixture and the concentration of hydrogen peroxide. A change in one of these two parameters produced profound effects on the total conversion to polymer as well as on the copolymer:- homopolymer ratio. By a suitable combination of initial pH and peroxide concentration, it was possible to synthesize graft copolymers whose homopolymer content approaches zero.

Wet-steam method of cellulose xanthate decomposition and carbon disulphide elimination from viscose rayon

Wet-steam method of cellulose xanthate decomposition and carbon disulphide elimination from viscose rayon

Cellulose xanthate solution in rotor type apparatus

Cellulose xanthate solution in rotor type apparatus

Spectrophotometric analysis of the reaction of cellulose xanthate acid decomposition

Spectrophotometric analysis of the reaction of cellulose xanthate acid decomposition

Kinetics of the cellulose xanthate solution process

Kinetics of the cellulose xanthate solution process

Spectrophotometric determination of the degree of esterification of the cellulose xanthate in regenerated-cellulose film

Spectrophotometric determination of the degree of esterification of the cellulose xanthate in regenerated-cellulose film

The water absorbency of hydrolyzed polyacrylonitrile‐grafted cellulose fibers

AbstractThe water absorbency of a bleached softwood kraft pulp, as measured by its water retention value (WRV), was increased up to 30 times by graft polymerizing polyacrylonitrile (PAN) and subsequently hydrolyzing it to sodium polyacrylate–polyacrylamide copolymer. WRV was found to be related to the initial PAN graft level rather than to the final sodium polyacrylate content, and was independent of the grafting process used. However, the ceric ion process was found superior to both the cellulose xanthate–H2O2 and ferrous ion–H2O2 redox systems in that it occasioned only a minor loss during the hydrolysis stage and the WRV was less affected by drying. The WRV remained constant as pH was lowered from 9 to 5 but dropped to the level of unmodified pulp at pH 3.5 where the sodium salt is fully converted to poly(acrylic acid). Retention of 1% aqueous NaCl was about 60% of the WRV. The swelling properties of the grafted fibers under various conditions appear to be explained by considering the grafting to act in two ways: (a) the introduction of a potentially hydrophilic component capable of generating swelling pressures and (b) the reduction in the cohesion of the fiber by the interposition of graft polymer chains in the fiber structure.

Grafting of acrylonitrile on cellulose xanthate

AbstractA study has been made of the grafting of acrylonitrile onto a bleached kraft pulp by application of the xanthate method developed by Faessinger and Conte. Acrylonitrile was grafted to the cellulose in aqueous suspension at 25°C, with cellulose xanthates of gamma numbers from 3 to 13. The reaction system contained 1–2 percent xanthogenated pulp, 0.2–0.9 mole/1. hydrogen peroxide, 0.45–1.0 mole/1. acrylonitrile, and the reaction time was 45 min. In some cases 0.6–60 mmole/1. sulfuric acid was added to the reaction system. The grafting yield was calculated from the nitrogen content of the grafts. The degree of polymerization (DP) of the grafted polyacrylonitrile, after hydrolytic removal of the cellulose, was calculated from the limiting viscosity number of dimethylformamide solutions of the polymer at 25°C, and use of the formula [ε] = 2.43 × 10−4 (M)0.75. The grafts were found to contain 10–35 percent polymer of DP = 350–1000, and an average number of 1–4 grafted polymer chains per cellulose chain, i.e., less than 5 percent of the number of xanthate groups initially present in the cellulose xanthate. The number of grafted polymer chains was dependent upon the pH, and the DP of the grafted polymer was dependent upon the monomer and xanthate concentrations; the higher the monomer concentration was, and the lower the xanthate concentration was, the higher it became. Possible mechanisms for grafting are discussed.

Wet xanthation of the soda cellulose

Wet xanthation of the soda cellulose

The structuration kinetics in the precipitation of cellulose xanthate from concentrated solutions

The structuration kinetics in the precipitation of cellulose xanthate from concentrated solutions

High-speed determination of the degree of cellulose xanthate esterification

High-speed determination of the degree of cellulose xanthate esterification

Cellulose xanthate dissolution in aqueous caustic soda solutions

Cellulose xanthate dissolution in aqueous caustic soda solutions

Precipitation of cellulose xanthate in multi-component salt solutions

Precipitation of cellulose xanthate in multi-component salt solutions

The swelling of cellulose xanthate in caustic soda solutions

The swelling of cellulose xanthate in caustic soda solutions

Variation of the gel particle content of viscose during the ripening process

The pattern of variation of the content in gel particles of the ripening viscose is of considerable practical significance which explains the large volume of research devoted to the subject /1-3/. In most cases (including those mentioned), however, no correlation was discovered between the number and size of the particles on the one hand and the variation of the principal physico-chemical characteristics of the viscose, e.g. ripeness and viscosity) on the other. The writers showed elsewhere that a close relation exists between the variation of the viscosity of viscose and the chemical processes taking place during ripening. The observed coincidence of minimum viscosity and maximum content in primary xanthate groups (completion of the redistribution process) led to the formulation of a hypothesis to the effect that these phenomena may be interrelated with the changes in the gel-particle spectrum in the solution. To verify this hypothesis a comparison was earried out of the variations of the viscosity of the viscose, the chemical composition of the cellulose xanthate and the gel particle spectrum during ripehing at 20°C. The viscosity of the viscose (a-cellulose 6.8%, NaOH 5.6%, Y2,3 = 65 appr.) was determined on a Heppler viscometer; the relative content in primary Y6 and secondary Y2 3 xanthate groups was determined spectrophotometrically while the number of gel partlcles of varlous slzes was determined on a TuRZG-I particle counter in accordance with a known procedure /5/. The results (Fig.1) demonstrate that in the ripening viscose the minimum viscosity and thus the completion of the redistribution of the xanthate groups coincide with the minimum content in gel particles of all sizes. With further ripening the onset of the

The kinetics of cellulose xanthate precipitation in viscose rayon spinning

The kinetics of cellulose xanthate precipitation in viscose rayon spinning

Fine structure of conidial development in Colletotrichum atramentarium

The development of sclerotia in Colletotrichum atramentarium was observed on cellulose xanthate membranes. The sclerotia were of the ‘strand’ type, i.e. formed by the intertwining of adjacent hyphae. Sclerotial hyphae secreted mucilage into which melanizing particles were deposited. Conidia were extruded through the apex of elongate conidiophores, the inner cell wall of the conidiophore giving rise to the conidial cell wall. The terms ‘enteroblastic’ and ‘phialidic’ are discussed in relation to spore production in this species.