Ethyl cellulose parameter

Lippold, B.H. Sutter, B.K. Lippold, B.C. Parameters controlling drug release from pellets coated with aqueous ethyl cellulose dispersions. Int. J. Pharm. 1989, 54, 15-25. 

Rowe, R.C. The prediction of compatibihty/incompatibility in blends of ethyl cellulose with hydroxypropyl methylcellulose or hydroxypropyl cellulose using 2-dimen-sional solubility parameter maps. J. Pharm. Pharmacol. 1986, 38, 214-215. 

Moldenhauer M, Nairn J. The control of ethyl cellulose microencapsulation using solubility parameters. / Control Release 1992 22 205-218. 

Thakare M, Israel B, Garner ST, Ahmed H, Garner P, Elder D et al. Formnlation parameters and release mechanism of theophylline loaded ethyl cellulose microspheres Effect of different dnal snrfac-tant ratios. Pharmaceutical Development and Technology. September-Octoher 2013 18(5) 1213-1219. PubMed PMID 21991996. 

G, K. Jani, M. C. Gohel. Effects of selected formulation parameters on the enuap-ment of diclofenac sodium in ethyl cellulose microspheres. J. Controlled Release. 43 245-250. 1997. 

Po ly (cap ro lac tone) and ethyl cellulose were obtained from Aldrich, and were used as received. They are seml-crystalllne materials and would be expected to exhibit localized changes In elastic properties at both and the melting point, T,. Physical parameters for these polymers were obtained from the Aldrich catalog. No value was available for the of PCAP the value In Table II Is estimated using the relationship... 

The lyotropic behavior of ethyl cellulose in various solvents (methanol, ethanol, diox-ane, acetic acid, acetic anhydride, m-cresol, phenol, etc.) was studied as a function of the critical concentration of the liquid crystal phenomenon produced by refractometry, polarized light microscopy, and optical transmission [118, 119]. It has been observed that critical concentration increases with decreasing the solubility of the solvent, and also that the critical concentrations for alcohols were much higher than those of other solvents with similar solubility parameters. 

BLO Blokhina, S.V., Alekseeva, O.V., Prusov, A.N., OlTdrovich, M.V., and Lokhanova, A.V., Gas-chromatographic study of the thermodynamic parameters of interaction between ethyl cellulose and low-molecular-mass compounds (Russ.), Vysokomol. Soedin., Ser. B, 40, 2099, 1998. 

Supercritical fluid processes is being explored as green alternative in polymer processing to improve the polymer properties, reduce cost, and extend the use for thermolabile active substance in the fields of cosmetics, food, and pharmaceuticals. Particularly, SAS process have been used at our facilities to precipitate a non-biodegradable polymer, ethyl cellulose, a biodegradable polymer, PLA, and a smart polymer with specific targeting area, Eudragit LIOO. Thermodynamics parameters such as the polymer... 

Triphenyl phosphate is a crystalline solid which has less compatibility with the polymer. This may be expected from solubility parameter data. It is often used in conjunction with dimethyl phthalate and has the added virtues of imparting flame resistance and improved water resistance. It is more permanent than DMP. Triacetin is less important now than at one time since, although it is compatible, it is also highly volatile and lowers the water resistance of the compound. Today it is essential to prepare low-cost compounds to allow cellulose acetate to compete with the synthetic polymers, and plasticisers such as ethyl phthalyl ethyl glycollate, which are superior in some respects, are now rarely used. 

Benzoic acid derivatives often contain amino, hydroxy, carboxy, and nitro groups. Analysis of substimted benzoic acids by thin layer chromatography was performed on silica gel, polyamide, and cellulose containing UF254 fluorescent indicator. For the mobile phase, different mixtures were used hexane-acetic acid hexane-ethyl acetate-formic acid chloroform-methanol-phosphoric acid cyclohexane-acetic acid benzene-ethanol etc. Because benzoic acid derivatives have similar retention parameters, their separation requires a thorough optimization of conditions (the nature of the stationary phase, the composition of the mobile phase, and the pH of the solutions). 

If the cellulose chain is assumed to have the same backbone conformation as in the ethylenediamine complex, then the structure is defined by nine potentially refinable parameters. The approximate chain orientation was refined first before the ethyl-enedlamlnes were added. Thereafter C-N sections were attached by hydrogen bonds at two of the three hydroxyls (l.e. 1,3-diamino-... 

D NMR was used to characterize native and acid hydrolyzed ethylcellulose (EC), a Hercules product widely used as a film-former in ink and coatings applications and as a binder and filler in pharmaceutical applications. An important parameter in controlling the properties of ethylcellulose is the degree of substitution (DS) of ethyl functionalities on the cellulose backbone. NMR is one technique that was used to determine both the total and positional DS (ethylation at the 2,3 and 6 positions of the anhydroglucose unit (AGU)). This analysis requires complete hydrolysis of the sample, and an improved acid hydrolysis technique was developed for this application. Two-dimensional (2-D) NMR techniques were used to confirm peak assignments related to positional DS determinations that were previously made by comparison with standards. In addition, 2-D NMR methods were used to evaluate positional DS of native ethylcellulose prior to acid hydrolysis. A comparison of the analytical results for the acid hydrolysate and native polymer will be discussed. 

The second approach for improving the processabihty of ICPs is to prepare their colloidal dispersions in water or an appropriate solvent The colloid dispersions of ICPs can be obtained by chemical or electrochemical oxidation of the monomer in the presence of a steric stabihzer [29-31].The key parameter for such synthesis is the choice of an appropriate steric stabihzer which adsorbs or grafts onto the polymer coUoidal particles to prevent their aggregation or precipitation. Several polymers such as polyfethylene oxide) [32], poly(vinyl pyrroHdone) [33,34], poly(vinyl alcohol) [35], ethyl hydroxy cellulose [36], poly(vinyl alcohol-co-acetate) [37], poly(vinyl methyl ether) [38,39] and block copolymer stabihzer [40] have been used as steric stabihzers to produce PPy coUoidal dispersions. Surfactants are also employed for the synthesis of ICP coUoidal dispersions [41,42]. Very recently, stable PPy dispersions were prepared by Lu et al. by polymerizing pyrrole in an aqueous medium containing different anionic salts such as sodium benzoate, potassium hydrogen phthalate, and sodium succinate [43]. These authors also reported that the conductivity of PPy dispersions was enhanced when sodium benzoate was used as dopant. Chemical oxidahve polymerization in the presence of PSS in aqueous medium produces coUoidal dispersions and improves processability [44]. CoUoidal dispersions... 

The relatively low solubility parameters (solpars) of the amorphous poly(l-olefins) have been compared with the solpars at 25°C) of other polymers poly(tetra-fluoroethylene), 13.5 poly(dimethylsiloxane) 15.5 polypropylene, 16.5 polyisobutylene, 16.5 polyethylene, 17.0 poly(ethyl methacrylate) 18.5 polystyrene, 18.5 poly(vinyl acetate) 20 cellulose nitrate, 21 poly(ethylene oxide), 24 and cellulose acetate, 24 [16]. 

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