Essay Example on The solution of methylcellulose is having a special gelation phenomenon


Medicine , Drugs








The solution of methylcellulose is having a special gelation phenomenon that commonly occurs by heating it so that it can change to gel and by cooking in order to form a clear solution Hirrien et al 1996. An increase in the viscosity of solution the gelation temperature of a given degree of substitution gets decreases with the addition of electrolytes lowers the gelation temperature Brandt 1986. The quantities of salts added also affected it. A few of these salts played a lead role in the prevention of dissolution of methylcellulose at ambient temperature Levy and Schwarz 1958. The addition of electrolytes and the procedure of heating destroy the hydrated structure. During this hydrogen bond between water and the polymer gets broken. When polar water mixed with organic solvents for instance alcohol or glycols are added then the solution of Methylcellulose gets stabilized Kundu et al 2003. Methylcellulose and the polar additives form strong hydrogen bonds which increase gelation temperatures and able to create more stable soluble complexes in the solution Brandt 1986 Kundu et al 2003.

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Methylcellulose takes the characteristics of solubility when the degree of substitution was different from 0 3 Nasatto et al 2014. The degree of substitution of methylcellulose is defined as the common numeral of replacing with hydroxyl faction for each unit of glucose. Preparation of diverse categories of methylcellulose can be done on the basis of a number of hydroxyl factions substituted Donges 1990. Commercial methylcellulose can be primed in accordance with the standard of Williamson ether production by heterogeneous etherification with methyl chloride. Therefore, it contains the allocation of heterogeneous substituents along the polymeric chains Timell and Purves 1951. The production of methylcellulose can be done by the development of conversion of cellulose into ether i.e the reaction between cellulose alkali and chloromethane or iodomethane. It becomes soluble in the aqueous system as the hydroxide group easily mixed with water. The methyl substituent prevents the chain packing in the cellulose crystalline phase. Methylcellulose depends on the degree of substitution and the distribution of methoxyl groups Hirrien et al 1996. Many factors like the degree of polymerization molecular mass and degree of substitution affect the rheological properties. The conditions of methylcellulose synthesis are imposed on these characteristics Mansour et al 1994.

Both methylcelluloses with a homogeneous and a heterogeneous block-wise distribution of substituent are known Hirrien et al 1996 Takahashi et al 1987. Two alternating methods through a heterogeneous path can be used to synthesize commercial methylcellulose. An alkaline medium Sodium hydroxide is useful for obtaining the alkali cellulose and for swelling of cellulosic fibers instead of water because cellulose is not soluble in water and in an organic solvent. It can be only reacted with the etherifying driving force for example iodomethane chloromethane or dimethyl sulfate. The studies about the surface activity of methylcellulose have been finished recently and also the influence of the methylcellulose molecular weight on the air and water Nasatto et al 2014. These leads to the effect of molecular weight on the interfacial properties to be established. The plane action of methylcellulose at equilibrium is not persuaded by molecular weight. The chemical change of cellulose and the division of hydrophobic groups by the side of the compound with repeating small molecules was a large pressure on the surface action Sarkar 1984. Characterization of cellulose and its derivatives methylcellulose by different techniques such as Fourier Transformation Infrared Spectroscopy. FTIR X Ray Diffraction XRD Scanning Electron Microscopy SEM Differential Scanning Calorimeter DSC Thermo Gravimetric. Analysis TGA and Intrinsic Viscosity that the degree of crystallinity surface morphology patterns enthalpy change of fusion temperature loss of mass percentage and average molecular weight degree of polymerization of cellulose and its derivatives methylcellulose can be measured by different techniques respectively.

FTIR techniques of cellulose and cellulose derivatives methylcellulose can be used as it provides a simple method of obtaining direct information on chemical changes that occur during various chemical treatments Ristolainen Alen and Pere 2002. The FTIR technique was used to determine functional groups of the cellulose and cellulose derivative methylcellulose synthesized by chemical methods. The onset of peak-end temperatures and the enthalpy changes of the phase transitions were characterized by evaluating the DSC thermogram. Several parameters used to characterize the ordered structure of cellulose including crystallinity. The determination of the crystallinity index is highly dependent on the characterization method. Park et al 2007 and calculating the highest crystallinity index by the XRD peak height method. The morphology of cellulose and cellulose derivatives can be investigated by SEM. The thermal stability of materials through the measure of weight change with temperature can be determined by TGA. The initial degradation temperature of sugarcane bagasse cellulose was lower than 100 ºC attributes for the loss of moisture due to evaporation Mandal and Chakrabarty 2011. Viscosity is defined as the resistance against the fluid flow which is affected by the binding between molecules that make up the solution or the solvent-solute relationship. Yasar Togrul and Arslan 2007 It calculates the degree of polymerization and average of molecular weight Evans 1973.

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