Films methylcellulose

At X-ray fluorescence analysis (XRF) of samples of the limited weight is perspective to prepare for specimens as polymeric films on a basis of methylcellulose [1]. By the example of definition of heavy metals in film specimens have studied dependence of intensity of X-ray radiation from their chemical compound, surface density (P ) and the size (D) particles of the powder introduced to polymer. Have theoretically established, that the basic source of an error of results XRF is dependence of intensity (F) analytical lines of determined elements from a specimen. Thus the best account of variations P provides a method of the internal standard at change P from 2 up to 6 mg/sm the coefficient of variation describing an error of definition Mo, Zn, Cu, Co, Fe and Mn in a method of the direct external standard, reaches 40 %, and at use of a method of the internal standard (an element of comparison Ga) value does not exceed 2,2 %. Experiment within the limits of a casual error (V changes from 2,9 up to 7,4 %) has confirmed theoretical conclusions. 

Cellulose is also commercially modified by acetylation to produce a material suitable for X-ray and cine film. Commercially cellulose ethers are also prepared, such as methylcellulose. This material is water-soluble and gives a highly viscous solution at very low concentrations. Hence it is widely used as a thickener in latex paints and adhesives, in cosmetics and for coating pharmaceutical tablets. 

Methylcellulose MC Cold water, GI fluids, organic solvents Useful polymer for aqueous films low-viscosity grade best... 

The main function of the foam stabilising agent is to reinforce the intercellular film wall by contributing rheological characteristics of viscoelasticity. The increased viscosity may also assist handling. The aim, as so often with auxiliaries, is to achieve an optimum balance. If the bubbles are too thin and wet too quickly they will collapse prematurely, whilst too stable a film could hinder uniform application. Examples of products used as foam stabilisers include thickening agents such as the polysaccharides, hydroxyethylcellulose, methylcellulose,... 

The materials used in these type of films include lipids, polysaccharides, and proteins. Starch (Maizura and others 2007), methylcellulose (Olivas and others 2003), hydroxypropyl cellulose (Brindle and Krochta 2008), chitosan (No and others 2007), xanthan gum (Mei and others 2002), alginate or zein (Zapata and others 2008), and soy protein (Park and others 2001) have been used for edible coatings. 

The photochemistry of four triphenylmethane acid dyes was studied in poly(vinyl alcohol), methylcellulose and gelatin films. These model systems were chosen with a view to elucidating the complex free-radical reactions taking place in the heterogeneous dyed wool/ water/air system on exposure to UV radiation. The dye fading mechanism seems to involve an excited triplet state of the dye molecule [ 164] The rate of fading is governed by ... 

Macleod et al. [92] have studied the potential of pectin-chitosan-hydroxypropyl methylcellulose films for colonic drug delivery [92]. The results showed that in all cases the tablets were able to pass through the stomach and small intestine intact. The tablets started to break up once they were in the colon, due to degradation of the coat by colonic bacteria. 

Macleod, G.S., Fell, J.T., Collett, J.H., Sharma, H.L., and Smith, A.M., Selective drug delivery to the colon using pectin chitosan hydroxypropyl methylcellulose film-coated tablets, Int J. Pharm., 187 251-257 (1999). 

Methylcellulose reduces surface and interfacial tension. Methylcellulose forms high strength films and sheets that are clear, water-soluble, and oil-and grease-resistant, and have low oxygen and moisture vapor transmission rates (see Barrier polymers). 

For hydroxypropyl methylcellulose acetate succinate, a novel enteric dry coating method has been developed [31]. The unique feature of this method is that the enteric polymer is added in powder form (e.g., mixed with talcum directly to tablets or pellets) whereas a plasticizer diluted with paraffin is sprayed separately. The tablet core temperature is around 40°C, and the film is cured for a short time. To achieve a homogenous film, the rates of powder feeding and plasticizer spray have to be adjusted such that the two processes start and end simultaneously. 

Nelson, K. L., and Fennema, O. R. (1991). Methylcellulose films to prevent lipid migration in confectionery products. J. Food Sd. 56 504-509. 

Methylcellulose occurs as a white, fibrous powder or granules. It is the methyl ether of cellulose. It is soluble in water and in a limited number of organic solvent systems. Aqueous solutions of Methylcellulose are surface active, form films upon drying, and undergo a reversible transformation from sol to gel upon heating and cooling, respectively. 

Generally, the barrier or rate-controlling films are more permeable to water than the carrier films. The materials used for this purpose consisted of a base, film forming water-soluble polymer in combination with at least one hydrophilic component such as hydroxypropyl methylcellulose or polyvinylpyrrolidone. The polymers used were the same as those for the carrier films. Some recent developments are discussed herein. 

Methylcellulose (MC) Cold water, GI fluids, and organic solvents Low-viscosity grades best for aqueous films... 

McLaren, D. D., and Hollenbeck, R. G. (1987), A high performance liquid chromatographic method for the determination of the amount of hydroxypropyl methylcellulose applied to tablets during an aqueous film coating operation, Drug Dev. lnd. Pharm., 13, 2179-2197. 

Hagenmaier, R.D., and Shaw, P.E. (1990). Moisture permeability of edible films made with fatty-acid and (hydroxypropyl)methylcellulose. J. Agricult. Food Chem. 38, 1799-1803. 

Psomiadou, E., Arvanitoyannis, 1., and Yamamoto, N. (1996). Edible films made from natural resources microcrystalline cellulose (MCC), methylcellulose (MC) and com starch and polyols. Part 2. Carbohydrate Polymers. 31, 193-204. 

Rico-Pena, D.C., and Torres, J.A. (1990). Edible methylcellulose-based films as moisture impermeable barriers in sundae ice cream cones. J. Food Sci. 55, 1468-1469. 

Like PVA, the viscosity enhancer hydroxypropyl methyl-cellulose is available in a variety of molecular weights and in formulations with different group substitutions. It has been shown to prolong tear film wetting time and to increase the ability of fluorescein and dexamethasone to penetrate the cornea. Hydroxypropyl methylcellulose 0.5% has been shown to exhibit twice the ocular retention time of 1.4% PVA. 

Substituted Cellulose Ethers. Since their introduction for ophthalmic use, MC and other substituted cellulose ethers such as hydroxyethylcellulose, hydroxypropylcel-lulose, hydroxypropyl methylcellulose (HPMC), and carboxymethylcellulose (CMC) have been used in artificial tear formulations.These colloids dissolve in water to produce colorless solutions of varying viscosity. They have the proper optical clarity, a refractive index similar to the cornea, and are nearly inert chemically. Their relative lack of toxicity, their viscous properties, and their beneficial effects on tear film stability have made cellulose ethers useful components of artificial tear preparations. Historically, the most frequently used representative of this group was MC. 

Cellulose is a fibrous, tough, water-insoluble, and crystalline substance. As a result of these characteristics, it is often converted to its derivatives in order to make it more useful. The most commonly used derivatives of cellulose are carbox-ymethylcellulose, methylcellulose, hydroxyethylceUulose, hydroxypropylcellulose, cellulose acetate, and cellulose xanthate (12). Among these derivatives, cellulose acetate and cellulose xanthate are cellulose esters, which are now widely used in the manufacturing of fibers, films, and in injection molding thermoplastics. 

Suspensions of polypyrrole were prepared by the FeCls oxidation of pyrrole in an aqueous solution of methylcellulose (49). The product was dried and yielded films with conductivities of 0.2 S/cm. Scanning electron microscopy revealed globular polypyrrole embedded in the methylcellulose matrix. After several months, these suspensions remained stable with no detectable precipitation. Similarly, the electropolymerization of 3-methyl-thiophene in solutions of poly(methyl methacrylate) and poly(vinyl chloride) was reported (50, 51). 

A hydroxypropyl methylcellulose film of pigment was exposed in a fadeometer for 3, 6, and 12 h. The rate at which the colorant degraded was noted from tint strength calculations and placed on a scale of 0-10, with the higher numbers indicating an increased tendency to fade. AL-aluminum lake. 

Johnson, K. Hathaway, R. Leung, P. Franz, R. Effect of triacetin and polyethylene glycol 400 on some physical properties of hydroxypropyl methylcellulose free films. Int. J. Pharm. 1991, 73, 197-208. 

Hjartstam, J. Borg, K. Lindstedt, B. The effect of tensile stress on permeability of free films of ethyl cellulose containing hydroxypropyl methylcellulose. Int. J. Pharm. 1990, 61, 101-107. 

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