Cellulose acetate characterization

Zugenmaier, P. (2004). Characteristics of cellulose acetates-Characterization and physical properties of cellulose acetates, Macromol. Svmn.. 208,81-166. 

Wet spinning. This technique is characterized by spinning a filtered viscous polymer mass, dissolved in a suitable solvent, into contact with a precipitation or coagulation bath. Polyacrylonitrile, polyvinyl acetate, cellulose acetate, and other materials are processed by this method. Thermal requirements for pigments are less stringent than for melt spinning but pigments are expected to be fast to the solvents and chemicals used. 

Eq. (5) in conjunction with Eqs. (8) and (9) have, so far, provided adequate representation of experimental isotherms6 32, which are characterized by an initial con vex-upward portion but tend to become linear at high pressures. Values of K, K2 and s0 have been deduced by appropriate curve-fitting procedures for a wide variety of polymer-gas systems. Among the polymers involved in recent studies of this kind, one may cite polyethylene terephthalate (PET) l2 I4), polycarbonate (PC) 19 22,27), a polyimide l6,17), polymethyl and polyethyl methacrylates (PMMA and PEMA)l8), polyacrylonitrile (PAN)15), a copolyester 26), a polysulphone 23), polyphenylene oxide (PPO)25), polystyrene (PS) 27 28), polyvinyl acetate 29) and chloride 32) (PVAc and PVC), ethyl cellulose 24) (EC) and cellulose acetate (CA) 30,3I>. A considerable number of gases have been used as penetrants, notably He, Ar, N2, C02, S02 and light hydrocarbons. 

Jansen PJ, Kemp CA, Maple SR, Baertschi SW. Characterization of Impurities found by interaction of Duloxetine HC1 with enteric polymers hydroxy-propyl methyl cellulose acetate succinate and hydroxypropyl methylcellulose phthalaie. J Pharm Sci 1998 87(1) 81—85. 

Cellulose acetate phthalate forms a pH-triggered phase transition system, which shows a very low viscosity up to pH 5. This system will coacervate in contact with the tear fluid (pH 7.4), forming a gel in few seconds and releasing the active ingredients over a prolonged period of time. The half-life of residence on the rabbit corneal surface was approximately 400 seconds compared to 40 seconds for saline. However, such systems are characterized by a high polymer concentration, and the low pH of the instilled solution may cause discomfort to the patient. 

Meier, M. M., Kanis, L. A., and Soldi, V. (2004), Characterization and drug-permeation profiles of microporous and dense cellulose acetate membranes Influence of plasticizer and pore forming agent, Int. J. Pharm., 278, 99-110. 

Vaithiyalingam, S. Khan, M.A. Optimization and characterization of controlled release multi-particulate beads formulated with a customized cellulose acetate butyrate dispersion. Int. J. Pharm. 2002, 234, 179-193. 

Electrophoresis on cellulose acetate paper has also been employed for the characterization of human alkaline phosphatase isoenzymes by Korner (K20, K21) and Posen et al. (P19). A modification of the Gomori technique (G11-G13) for the histochemical localization of alkaline phosphatase was made by Allen and Hyncik (AlO) to visualize the enzyme zones in the starch and agar gels. 

Table I. Experimental Reverse Osmosis Data for the System NaCl-H O and Glycerol-H O Using Porous Cellulose Acetate Membranes and Parameters Characterizing Membranes...

Recent studies using Infrared Spectrocopy IR to characterize the state of water in desalination membranes have concluded that the water sorbed in these membranes has a low degree of association and that bonds between water and the membrane are considerably weaker than those in liquid water (1,2). These conclusions have been made for widely differing membrane materials such as cellulose acetate (1,2),polyimide, and porous glass and appear to contradict the conclusions obtained from pNMR differential scanning calorimetry (9-11) and transport... 

The most prominent cellulose ester produced on the industrial scale is cellulose acetate. The reaction is usually performed with acetic anhydride and with sulfuric acid as a catalyst. To minimize heterogeneities, acetylation is allowed to run nearly to completion, and subsequently partial ester hydrolysis is initiated by the addition of water until a desirable solubility is achieved that corresponds to a DS of about 2.5. Such higher acyl homologues as propanoyl or butanoyl exhibit more thermoplastic properties. Many specialized esters such as chiral (-)-menthyloxyacetates, furan-2-carboxylates, or crown-ether-containing acylates have been prepared on the laboratory scale and characterized by NMR spectroscopy. Various procedures have been applied, using anhydrides and acyl chlorides as acylating agents in combination with such bases as pyridine, 4-dimethylaminopyridine (DMAP), or iV,iV -carbonyldi-imidazole. The substitution pattern of cellulose acetates has also been modified by postchemical enzymatic deacetylation. Cellulose 6-tosylates have been used as activated intermediates for nucleophihc substitution to afford 6-amino-6-deoxy, 6-deoxy, or 6-deoxy-6-halo-celluloses. ... 

B. Saake, C. Altaner, S. -J. Lee, and J. Puls, Endoglucanase degradation and enzyme-aided characterization of cellulose acetates, Macromol. Symp., 223... 

Choudhury, P.K., Kar, M., Chauhan, C.S., 2008. Cellulose acetate microspheres as floating depot systems to increase gastric retention of antidiabetic dmg formulation, characterization and in vitro-in vivo evaluation. Dmg Development and Industrial Pharmacy 34, 349—354. 

Cao, Y.L. Zhang, H.Q.J. Homogeneous synthesis and characterization of cellulose acetate butyrate (CAB) in l-aUyl-3- methylimidazolium chloride (AmimCl) ionic liquid. Ind. Eng. Chem. Res. 2004,50 (13), 7808-7814. 

Sarath C.I., Balagani P.K., and Korlakanti N.J. Characterization of Glibenclamide loaded cellulose acetate microparticles prepared by an emulsion solvent evaporation method. J. Pharm. Res. 7(8)... 

Zavastin, D., Cretescu, I., Bezdadea, M., Bourceanu, M., DrSgan, M., Lisa, G., Mangalagiu, I., Vasic, V., Savic, J. (2010). Preparation, characterization and applicability of cellulose acetate-polyurethane blend membrane in separation techniques, U icochenrfihgjAsgec 370,120-128. 

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