Effect of Acetylation on Water-Binding Properties of Cellulose

Bletzinger, John C.

doi:10.1021/ie50400a019

Cited by 25 publications

(7 citation statements)

References 8 publications

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“…In general, higher negative zeta potential, which often is indicative of a higher density of anionic carboxylate groups at a cellulosic surface, has been correlated to higher degrees of swelling (Ribitsch et al 2001). Less swelling has been observed in cellulosic samples containing hydrophobic substituent groups (Bletzinger 1943). In simple terms it is reasonable to expect that interactions with water ought to be weakened as the proportion of OH groups becomes smaller.…”

Section: Swelling Vs Chargementioning

confidence: 98%

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Colloidal stability and aggregation of lignocellulosic materials in aqueous suspension: A review

Hubbe

Rojas

2008

BioRes

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Aqueous dispersions of lignocellulosic materials are used in such fields as papermaking, pharmaceuticals, and preparation of cellulose-based composites. The present review article considers published literature dealing with the ability of cellulosic particle dispersions (fiber, fines, nanorods, etc.) to either remain well dispersed or to agglomerate in response to changes in the composition of the supporting electrolyte solution. In many respects, the colloidal stability and coagulation of lignocellulosics can be understood in terms of well-known concepts, including effects due to osmotic pressure arising from overlapping electrostatic double layers at the charged surfaces. Details of the morphology and surface properties of lignocellulosic materials give rise to a variety of colloidal behaviors that make them unique. Adjustments in aqueous conditions, including the pH, salt ions (type and valence), polymers (charged or uncharged), and surfactants can be used to control the dispersion stability of cellulose, lignin, or wood-extractive materials to serve a variety of applications.

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Section: Swelling Vs Chargementioning

confidence: 98%

“…Alternatively, cellulosic surfaces can be rendered hydrophobic by derivatization (Bletzinger 1943;Pothan et al 2002;Andresen and Stenius 2007). Acetylation is an especially interesting and flexible approach, and the results depend both on the extent and the location of treatment.…”

Section: Bioresourcescommentioning

confidence: 99%

Colloidal stability and aggregation of lignocellulosic materials in aqueous suspension: A review

Hubbe

Rojas

2008

BioRes

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“…The desorbing cottons were prepared by 1 soaking the samples in water for 16 hr., after which they were allowed to dry to selected moisture contents by exposure to the atmosphere or in constanthumidity chambers. While no special effort was made to assure moisture equilibrium for each of the samples, reproducible results were obtained for a number of samples conditioned in the same way but for different lengths of time.…”

Section: Moisture Sorptionmentioning

confidence: 99%

Influence of Moisture Sorption and Other Pretreatments on the Acetylation of Cotton with Acetic Anhydride and Pyridine

Blouin

Reeves

Hoffpauir

1956

Textile Research Journal

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TWO different methods have been used for the partial acetylation of cellulose. One of these, acidcatalyzed acetylation, has been the subject of numerous reports [2 through 5, 7, 8, 15, 17, 19] establishing the influence of pretreatments and conditions of reaction in the production of partially acetylated cotton. The other, reaction with acetic anhydride in the presence of pyridine [10], has received less attention. The limited investigations of this reaction which have been reported [1, 9 through 11, 14, 18] indicate the importance of swelling agents in increasing the reactivity of cellulose. However, the influence of moisture sorption and other pretreatments on the acetylation of cotton with acetic anhydride and pyridine has not been systematically investigated.In order to obtain such information, the effect of moisture content and previous sorption history on the extent of acetylation under a selected set of conditions have been studied. The increased reactivity of dried cotton, due to pretreatment with agents other than water, and the reversibility on drying of the eff ect of treatment with sodium hydroxide, a swelling agent which penetrates the crystalline regions, has also been investigated.In his discussion of cellulose reactions, Heuser [12] concluded that acetylation is a reaction which exhibits no marked preference for either the primary or secondary hydroxyl groups of cellulose. However, in order for reaction to take place, the reagent must penetrate to the hydroxyl groups. Consequently, the rate of acetylation (or the extent of reaction under certain arbitrary conditions) is a function of the submicroscopic structure. When cellulose absorbs, water swelling occurs as the water penetrates the intermicellar spaces, and the accessibility of the hydroxyl groups to chemical reaction is increased. In order to obtain penetration into the intramicellar spaces, alkalis, organic bases, or other strong swelling agents are required. Whether regarded as amorphous and crystalline or accessible and inaccessible, the duality of submicroscopic structure of cellulose plays an important role in the acetylation of cotton. As a result, changes in reactivity toward acetylation may be regarded as a reflection of changes in the submicroscopic structure of cotton. Moisture SorptionEmpire, Stoneville 2B, and Rowden 41B cottons were selected to obtain specimens differing in maturity and fineness (Table I ) . In addition to acetylation of all three raw cottons, the first two were acetylated after purification by successive extraction with hot alcohol and boiling in 1% alkali [13]. The cotton samples were brought to the absorbing side of the moisture sorption cycle by drying them in an oven at 110° C. for 16 hr. and then conditioning them at suitable relative humidities until they had reached the desired moisture contents.The desorbing cottons were prepared by

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“…THE partial acetylation of cotton has been found to produce a modified cellulose with improved resistance to chemical and heat degradation [4,14] _ and to microbiological deterioration [ 6, 8, 25 ~ . Whik the general appearances of the fiber and its products are essentially unchanged from that of scoured cotton, significant changes are found in the physical properties of the fibers [2,4,13,14,16]. These changes were shown to be related both to inherent characteristics of the cotton and to the extent of Chemical substitution [ 4,14,16,17,23,24).…”

mentioning

confidence: 99%

“…The rate of strain 2 The mention of trade names does not imply their endorsement by the Department of Agriculture over similar products not mentioned. Inad~ on unprocessed cotton fibers before acetylation and after acetylations to two different levels of substitution.…”

mentioning

confidence: 99%

Physical Properties of Fibers and Yarns of Partially Acety lated Cottons

Orr

Weiss

Burgis

et al. 1957

Textile Research Journal

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Samples of cotton of Deltapine, Rowden, and Stoneville varieties were partially acetylated as bulk cotton and as untreated 14/3 yarns to acetyl contents ranging from 9 to 26%. Breaking loads and elongations at break of single fibers, fiber bundles, and yarns were decreased by the partial acetylation up to about 17%, but showed a tendency to increase above 20% acetyl content. Moisture conditions have less effect on tenacity of yarns of 25% than on those with lower acetyl content. Tenacities of the acetylated yarns when wet were slightly lower, and when desiccator-dried were higher than those of the untreated controls. Below 15%, the relation of density to acetyl content was consistent with calculations based on the preferential reaction of amorphous cellulose in the initial stages of the reaction. Resistançe to heat degradation increased with acetyl content up to 25% acetyl. The pH of the water used to rinse the reacted yarns was an important factor influencing heat degradation. Maximum retention of strength occurred when the wash water was in the pH range of 10-11. A slight but consistent difference in heat resistance of the partially acetylated cottons was associated with different varieties.. THE partial acetylation of cotton has been found to produce a modified cellulose with improved resistance to chemical and heat degradation [4,14] _ and to microbiological deterioration [ 6, 8, 25 ~ .Whik the general appearances of the fiber and its products are essentially unchanged from that of scoured cotton, significant changes are found in the physical properties of the fibers [2,4,13,14,16]. These changes were shown to be related both to inherent characteristics of the cotton and to the extent of Chemical substitution [ 4,14,16,17, 23,24).In a previous investigation of the fiber properties . of partially acetylated cottons ( PA cottons) [ 16t he degree of substitution was limited to a narrow range, averaging about 247( acetyl. The reactions were carried out with the yarns held under sufhcient tension while in the acetylating solution to prevent a contraction in length. Partial acetylation within t the range of 22-267c has been found to produce textile products with excellent heat and rot resistance. However, several properties of the fibers and yarns, such as low elongation and processing characteristics, appeared undesirable for certain textile uses. In an attempt to define more fully the factors responsibte for these undesirable fiber properties and to seek conditions for partial acetylation with greater potentialities for producing satisfactory textile fibers,

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Effect of Acetylation on Water-Binding Properties of Cellulose

Cited by 25 publications

References 8 publications

Colloidal stability and aggregation of lignocellulosic materials in aqueous suspension: A review

Colloidal stability and aggregation of lignocellulosic materials in aqueous suspension: A review

Influence of Moisture Sorption and Other Pretreatments on the Acetylation of Cotton with Acetic Anhydride and Pyridine

Physical Properties of Fibers and Yarns of Partially Acety lated Cottons

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