Ethylcellulose membranes

Ito A and Hwang S. Permeation of propene and propylene through cellulosic polymer membranes. J Appl Polym Sci 1989 38 483 90. Sridhar S and Khan A. Simulation studies for the separation of propylene and propane by ethylcellulose membrane. J Membr Sci 1999 159 209-219. 

Elat ethylcellulose membranes of thickness 28-80 pm and EC magnetic membranes of thickness 90-202 pm (depending on magnetic powder granulation and on the amount of added powder) were used. Both types of films were made by casting. The solution in... 

Kusunoki, M., Ikeuchi, H., Yanagi, H., Noda, M., Tonouchi, H., Mohri, Y., Uchida, K., Inoue, Y., Kobayashi, M., Miki, C., Yamamura, T. Bioresorbable hyaluronate-carboxym-ethylcellulose membrane (Seprafilm) in surgery for rectal carcinoma a prospective randomized clinical trial. Surg. Today 35(11), 940-945 (2005)... 

Polyamide, collodion (cellulose nitrate), ethylcellulose, cellulose acetate butyrate or silicone polymers have been used for preparation of permanent microcapsules. This method offers a double specificity due to the presence of both the enzyme and a semipermeable membrane. Moreover, it allows simultaneous immobilization of many enzymes in a single step and the surface area for contacting the substrate and the catalyst is large. The need of high protein concentration and the restriction to low molecular weight substrates are the main limitations of enzyme microencapsulation. 

The solubility of gases in elastomeric membranes is related to the molecular weight of the diffusate molecule. Thus the ratio of the diffusion of oxygen to that of nitrogen differs in natural rubber and in ethylcellulose. 

Materials that form a permeable membrane include fats, bee wax, carnauba wax, cetyl alcohol, cetylsteryl alcohol, zein, acrylic esters, silicone elastomers, and ethylcellulose (14). Aqueous dispersions of water-insoluble polymers are commonly used for sustained-release film coatings. Examples of commercially available aqueous polymer dispersions include Surelease-containing ethylcellulose, Aquacoat-containing... 

Containment behind a Barrier polylysine, ethylcellulose, emulsion, synthetic membrane... 

When ketoprofen was loaded with chitosan-coated ethylcellulose microparticles and the plain ethylcellulose microparticles, similar findings were obtained. Although ketoprofen is well absorbed from the GI tract, chitosan appears to influence the absorption profile. Chitosan allowed the particles to make contact with the mucosal membrane and be retained at adhesive sites, which means that the drug remains in the small intestine longer. This facilitated the absorption of ketoprofen in chitosan-coated microparticles loaded with ketoprofen. Chitosan is considered to improve the absorption properties of plain microparticles [33]. 

Nixon JR and Wong KT. Evaluation of drug permeation through polymeric membrane as a model for release (II) ethylcellulose-walled microcapsules. Int. J. Pharm. 1990 58 31 0. 

To improve the hemocompatibility of BOs, and avoid direct contact between the blood and gas phases, a nonporous membrane was placed between the blood and gas phases giving rise to membrane BOs [13-17]. The initial challenge in membrane technology was to produce reliable membranes with high permeabilities for O2 and CO2. The first nonporous membrane materials included polyethylene, polypropylene, and ethylcellulose. The permeability of CO2 in these membrane materials was only five times greater than the permeability of O2. Consequently, given the much lower CO2, concentrations of CO2 transfer were membrane limited. 

Pennkinetic System Skye Pharma AG, Muttenz, Switzerland The system combines CR principles of ion exchange with membrane diffusion. The system is made up of an ion-exchange polymer-drug complex as a core material, which is subsequently coated with ethylcellulose to form a water insoluble but permeable coating. Release rates are relatively constant and unaffected by variable conditions of the GI tract. The system can be formulated in capsule form as well as suspensions. Delsym (Dextromethorphan), Corsym (Chlorpheniramine) and Cold Factor 12 (Phenylpropanolamine). 

Ichikawa, H. Fukumori, Y. A novel positively thermosensitive controlled-release microcapsules with membrane of nano-sized poly(V-isopropylacrylamide) gel dispersed in ethylcellulose matrix. J. Controlled Release 2000, 63, 107-119. 

Ethylcellulose has also been used as a backing membrane on mucoadhesive patches intended for buccal administration. The... 

The suitability of several other membranes for demineralizing saline waters was then investigated. Commercially available membranes of polystyrene, polyethylene terephthalate), copolymer poly (vinyl chloride)-poly (vinyl acetate), rubber hydrochloride, cellulose triacetate, and ethylcellulose were tested. Only the cellulose triacetate and ethylcellulose gave high degrees of desalinization... 

Ethylcellulose capsules can be prepared by a method adapted from that described previously by Huang and Ghebre-Sellassie [35]. An ethanolic phase, containing ethylcellulose and hydroxypropylated CyD (HP-a- or HP-yS-CyD), is dispersed in a heptane-paraffin mixture. Ethanol diffuses and dissolves in heptane before being evaporated at room temperature. The microcapsules obtained have a thick membrane (ratio of cavity membrane radii = 1 2) [12]. Interestingly, this method allows the encapsulation of relatively poorly water-soluble molecules, which have to be soluble in ethanol and insoluble in heptane-paraffin. 

Herzog and Swarbrick have constructed a polymeric, nonporous, model membrane consisting of 44% ethylcellulose, 44% biological materials including lecithin, cephalin and cholesterol, and 12% mineral oil. When tested in a two-compartment transport ceil using salicylic acid as penetrant, this membrane was found to mimic the functionality of natural barriers. The transport of salicylic acid follows apparent first-order kinetics, with the membrane retaining approximately 2% of the solicylic acid. Both lecithin and mineral oil are found to potentiate transport, apparently due to their contribution to the nonpolar character of the barrier. 

X.-G. Li, M.-R. Huang, G.-F. Gu, W. Qiu, J.-Y. Lu, Actual air separation through poly(aniline-co-toluidine)/ethylcellulose blend thin-fihn composite membranes, J. Appl. Polym. ScL, 75, 458 (2000). 

The theory of Kamide (1990) allows determining the properties of the polymeric membrane covering a particle both in terms of number of pores, their conformation and apparent diffusivity. Basically, it is necessary to know the volumes ratio/ between solvent and polymer. These two phases are respectively identified as poor and rich phases. In our formulation and experimental activity we worked with ethylcellulose polymer and cyclohexane solvent. Consequently, the specific values defined in the following refer to such pairing. The membrane is formed by the separation of the polymer from the poor phase and the consequent coagulation of the polymer particles. It is possible to outline three main steps for the membrane formation ... 

---