Cellulose surface modifications

Surface Modifications of Cellulose and Polyvinyl Alcohol, and Determination of the Surface Density of the Hydroxyl Group... 

Surface Modification of Cellulose and PVA Films. Cellulose, as well as PVA,is known to be a typical non-ionic, hydrophilic polymer possessing hydroxyl groups. As this group has a high reactivity,chemical modification of these polymers is relatively easy and, in fact, has been the subject of extensive research. However, so far as we know, no work has been reported concerned with reactions occurring only at the surface of films or fibers from these polymers. 

Bieser A (2008) Surface modifications by hydrogelation and by coating with antimicrobial cellulose derivatives Dissertation, University of Freiburg... 

In conclusion, we would like to dwell on the fact that the present study demonstrates the feasability of a photochemical treatment, through a grafting reaction, of a cellulosic substrate. It is obvious that the results cannot be easily extrapolated to the case of an industrial process of surface modification of the pulps. In fact, due to its low penetration, UV light can be... 

Beeskow TC, Kusharyoto W, Anspach FB, and Kroner KH. Surface modification of microporous polyamide membranes with hydroxyethyl cellulose and their application as affinity membranes. J. Chromatogr. A 1995 715 49-65. 

Deposition of polyelectrolytes Lajimi et al. [56] explored the surface modification of nanofiltration cellulose acetate (CA) membranes by alternating layer-by-layer deposition of acidic chitosan (CHI) and sodium alginate (AEG) as the cationic and anionic polyelectrolyte, respectively. The supporting CA membranes were obtained by a phase separation process from acetone/formamide. The permeation rate of salted solutions was found to be higher than that of pure water. The rejection of monovalent salt was decreased, while that of divalent salt remained constant so that the retention ratio increased. Increasing the concentration of feed solutions enhanced this selectivity effect. 

Feijani, E. et al.. Bulk and surface modification of cellulose diacetate based RO/NF membranes by polymethyUiydrosiloxane Preparation and cbaracterization. Desalination, 146, 325, 2002. 

The microspheres mentioned above are all spherical and no change of the diameter and aggregation of the microspheres takes place during the reaction of surface modification. The surface charge of every microsphere can be determined by electrophoresis. For instance, the zeta potentials of our cellulose triacetate, Cell-OH, crosslinked Cell-OH, Cell-CM, Cell-SE, Cell-NHa, Cell-DEAE, Cell-DEAE(Me), and benzyl cellulose microspheres were —19.9, —2.1, —2.7, —17.1, —20.9, +4.6, +14.2, +15.1, and —65.2 mV, respectively. This result indicates that anionic and cationic microspheres with the same average diameter but different surface charges can be prepared by this method. 

In applications to sausage products which are produced in cellulose casings, the coagulation of surface proteins is an essential functional effect of smoke solutions. While the above mentioned carbonyl-amine reaction is one of two mechanisms of surface modifications, the acidity of natural smoke flavourings is an even more valuable processing aid for meat surface protein coagulation. 

Changes in cross-flow velocity or transmembrane pressure cannot always alleviate fouling. Membranes made from hydrophilic polymers like cellulose acetate are generally less prone to fouling than the hydrophobic polymers. However, cellulose acetate is limited in its tolerance to high or low pH, organic solvents and elevated temperature. In some cases, surface modification of the more chemically-resistant polymers has rendered them less susceptible to fouling. 

One of the most promising approaches regarding the surface modification of cellulose fibres toward the preparation of a sorbent based on cellulose substrate for the uptake of organic pollutant, calls upon CDI as an activation agent. CDI was first used in 1960 by Paul and Anderson [33] as a peptide coupling by... 

S. Alila, A.M. Ferraria, A.M. Botelho do Rego, and S. Boufi, "Controlled surface modification of cellulose fibers by amino derivatives using N,N -carbonyldiimidazole as activator", carbohydrate polymers, Vol. 77, issu 3, pp. 553-562, 2010. 

Adsorption of alkoxysilanes onto cellulose fibers also holds promise for modification of the cellulose surface. The basic formula of the silane-coupling agents used has an organofunctional group on one side of the chain and an alkoxy group on the other. Abdelmouleh studied the adsorption of several prehydrolyzed alkox-... 

H. Brumer, Q. Zhou, M. Baumann, K. Carlsson, and T. T. Teeri, Activation of crystalline cellulose surfaces through the ehemoenzymatic modification of xyloglucan, J. Am. Chem. Soc., 126 (2004) 5715-5721. 

Native cellulose are commonly modified by physical, chemical, enzymic, or genetic means in order to obtain specific functional properties, and to improve some of the inherent properties that limit their utility in certain application. Physical/surface modification of cellulose are performed in order to clean the fiber surface, chemically modify the surface, stop the moisture absorption process, and increase the surface roughness. " Among the various pretreatment techniques, silylation, mercerization, peroxide, benzoylation, graft copolymerization, and bacterial cellulose treatment are the best methods for surface modification of natural fibers. 

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