Cellulose study

The changes in the yields of 1,6-anhydrosaccarides, under the conditions of analytical pyrolysis which model the fast pyrolysis conditions, were different for each cellulose (Fig.l.). The celluloses studied can be subdivided into two groups with respect to the Lg-none yield A vice 11 and Kraft pulp in one group, and Munktell. Thermocell and Taircell in another. 

H Tylli, I Forsskahl, and C Olkkonen. Photochromic Behaviour of Ozonated and Photoirradiated Cellulose Studied by Fluorescence Spectroscopy. Cellulose 3 203, 1996. 

Wilkinson, F., Leicester, P.A., Ferreira, L.F.V., and Freires, V.M.M.R. (1991) Photochemistry on surfaces triplet-triplet energy transfer on microcrystalline cellulose studied by diffuse reflectance transient absorption and emission spectroscopy, Photochem. Photobiol., 54, 599-608. 

L. Kuutti, J. Peltonen, J. Pere, and O. Teleman, Identification and surface stracture of crystalline cellulose studied by atomic force microscopy, J. Microsc., 178 (1995) 1-6. 

Subnanometer Hole Properties of Cellulose Studied by Positron Annihilation Lifetime Spectroscopy... 

NMR can be employed effectively for examination of many modification processes for cellulose. Studies on acetylation have been reviewed by Usmanov [101]. The quantitative analysis of NMR data relies upon information derived from specifically modified model analogues. Similarly, C chemical shift data for various cellulose oligomers permit the analysis of the spectra of samples of cellulose acetate. Quantitative analyses for the distribution of acetate groups in cellulose acetates of various types have been achieved. 

Kocherbitov, V., Ulvenlund, S., Kober, M., Jarring, K., Amebrant, T., 2008. Hydration of microcrystaUine cellulose and milled cellulose studied by sorption calorimetry. Journal of Physical Chemistry B 112, 3728-3734. 

Johansson, LS Campbell, JM. Reproducible XPS on biopolymers cellulose studies. 

Barnes and co-workers have studied mixed-monolayer systems [278,281,283,284] and found some striking nonidealities. Mixed films of octadecanol and cholesterol, for example, show little evaporation resistance if only 10% cholesterol is present [278] apparently due to an uneven granular microstructure in films with cholesterol [284]. Another study of cellulose decanoate films showed no correlation between holes in the monolayer and permeation rate [285]. Polymerized surfactants make relatively poor water evaporation retarders when compared to octadecanol [286]. There are problems in obtaining reproducible values for r [287] due to impurities in the monolayer material or in the spreading solvent. 

Holmberg M ef al 1997 Surface force studies of Langmuir-Blodgett cellulose films J. Colloid Interface Sci. 186 369-81... 

Many ceUulosic derivatives form anisotropic, ie, Hquid crystalline, solutions, and cellulose acetate and triacetate are no exception. Various cellulose acetate anisotropic solutions have been made using a variety of solvents (56,57). The nature of the polymer—solvent interaction determines the concentration at which hquid crystalline behavior is initiated. The better the interaction, the lower the concentration needed to form the anisotropic, birefringent polymer solution. Strong organic acids, eg, trifluoroacetic acid are most effective and can produce an anisotropic phase with concentrations as low as 28% (58). Trifluoroacetic acid has been studied with cellulose triacetate alone or in combination with other solvents (59—64) concentrations of 30—42% (wt vol) triacetate were common. 

Other patents (81,82) coveted the preparation of cellulose solutions using NMMO and speculated about their use as dialysis membranes, food casings (sausage skins), fibers, films, paper coatings, and nonwoven binders. NMMO emerged as the best of the amine oxides, and its commercial potential was demonstrated by American Enka (83,84). Others (85) have studied the cellulose-NMMO system in depth one paper indicates that further strength increases can be obtained by adding ammonium chloride or calcium chloride to the dope (86). 

A. Fundamental Study ofi the Pyrolysis ofi Cotton Cellulose to Provide Infiormation Neededfor Improvement ofiFlame Kesistant Treatmentsfior Cotton, Pinal Report 1959—1964 on PL 480 Project No. URE-29-(20)-9 Grant No. PG-UK-108-59, The Cotton, Silk and Man-Made Pibers Research Association, Didsbury, UK, 1964. 

Polymer Blends. The miscibility of poly(ethylene oxide) with a number of other polymers has been studied, eg, with poly (methyl methacrylate) (18—23), poly(vinyl acetate) (24—27), polyvinylpyrroHdinone (28), nylon (29), poly(vinyl alcohol) (30), phenoxy resins (31), cellulose (32), cellulose ethers (33), poly(vinyl chloride) (34), poly(lactic acid) (35), poly(hydroxybutyrate) (36), poly(acryhc acid) (37), polypropylene (38), and polyethylene (39). 

The chemical and physical properties of cellulose depend ia large measure on the spatial arrangements of the molecules. Therefore, cellulose stmctures have been studied iatensively, and the resulting information has been important ia helping to understand many other polymers. Despite the extent of work, however, there are stiU many controversies on the most important details. The source of the cellulose and its history of treatment both affect the stmcture at several levels. Much of the iadustrial processiag to which cellulose is subjected is iatended to alter the stmcture at various levels ia order to obtain desired properties. 

Fig. 2. A representation of the cellulose chain ia solution, projected against three two-dimensional surfaces. The circles represent the oxygen atoms that link the iadividual glucose residues, and the lines take the place of the sugar residues. This result of a modeling study (39) iadicated a molecule somewhat more...

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