Aqueous hydroxypropyl cellulose solutions

Aqueous hydroxypropyl cellulose solutions amplification vs. wave number, 275,277/ apparent diffusivity vs. temperature, 275,277/ calculation of maximum scattered intensity, 278... 

Aqueous hydroxypropyl cellulose solutions have optimum stability when the pH is maintained at 6.0-8.0, and also when the solution is protected from light, heat, and the action of microorganisms. 

Werbowyj, R.S. Gray, D.G. Liquid crystalline structure in aqueous hydroxypropyl cellulose solutions. Molec. Crystals Liquid Crystals 1976, 34 (4), 97-103. 

Nishio, Y. Chiba, R. Miyashita, Y. Oshima, K. Miyajima, T. Kimura, N. Suzuki, H. Salt addition effects on mesophase structure and optical properties of aqueous hydroxypropyl cellulose solutions. Polym. J. 2002, 34 (3), 149-157. 

Watanabe J, Nagase T (1988) ThermoLopic polypeptides. 5. Temperature dependence of cholesteric pitches exhibiting a cholesteric sense inversion. Macromolecules 21(1) 171-175 Wenzel RN (1936) Resistance of solid surfaces to wetting by water. Ltd Eng Chem 28(8) 988-994 Werbowyj RS, Gray DG (1976) Liquid crystalline structure in aqueous hydroxypropyl cellulose solutions. Mol Cryst Liq Cryst 34(4) 97-103... 

SCH Schmidt, J., Burchard, W., and Richtering, W., Shear-induced mixing and demixing in aqueous methyl hydroxypropyl cellulose solutions. Biomacromolecules, 4, 453, 2003. 

A typical polymerization run was conducted in a stirred one-gallon (3.7 liters) stainless steel reactor equipped with baffles and a cooling coil, rated at 69 MPa. The vessel was charged with 2,470 ml of water, 908 g of vinylidene fluoride, 30 g of an aqueous methyl hydroxypropyl cellulose solution, and 5 g of tert-butyl peroxypivalate. Water pressure was raised to 5.5 MPa at 25°C under which the liquid monomer density is 0.69 g/ml. The reactor was heated to 55°C, increasing the pressure to 13.8 MPa. The reaction was continued for four hours during which 800 ml of water was pumped into the vessel to keep the pressure constant. 

Hydroxy propyl methyl cellulose (HPMC).35 HPMC is a partly O-methylated and 0-(2-hydroxypropylated) cellulose available in several grades that vary in viscosity and extent of substitution. It is used widely in pharmaceutical formulations, especially in oral products, as a tablet binder, in film coating, and as controlled release matrix. Soluble in cold water, it forms a viscous colloidal solution. For a 2% aqueous solution (20°C), viscosity can range from 2.4 to 120,000 mPa-s. High-viscosity grades can be used to retard the release of water-soluble drugs from a matrix. 

Liquid-crystalline solutions and melts of cellulosic polymers are often colored due to the selective reflection of visible fight, originating from the cholesteric helical periodicity. As a typical example, hydroxypropyl cellulose (HPC) is known to exhibit this optical property in aqueous solutions at polymer concentrations of 50-70 wt%. The aqueous solution system is also known to show an LCST-type of phase diagram and therefore becomes turbid at an elevated temperature [184]. 

Aqueous solutions of hydroxypropyl cellulose are stable at pH 6.0-8.0, with the viscosity of solutions being relatively unaffected. However, at low pH aqueous solutions may undergo acid hydrolysis, resulting in chain scission and hence... 

Increasing temperature causes the viscosity of aqueous solutions to decrease gradually until the viscosity drops suddenly at about 45°C owing to the limited solubility of hydroxypropyl cellulose. However, this process is reversible and on cooling the original viscosity is restored. 

Ultraviolet light will also degrade hydroxypropyl cellulose and aqueous solutions may therefore decrease slightly in viscosity if exposed to light for several months. 

Table VI Compatibility of hydroxypropyl cellulose (N/sso HPQ with inorganic salts in aqueous solutions.

The addition of sodium chloride to aqueous spray-coating solutions containing hydroxypropyl cellulose or hypromellose suppresses the agglomeration of crystalline cellulose particles. Sodium chloride can also be used to modify drug release from gels and from emulsions.It can be used to control micelle size, and to adjust the viscosity of polymer dispersions by altering the ionic character of a formula-... 

Aqueous sodium chloride solutions are corrosive to iron. They also react to form precipitates with silver, lead, and mercury salts. Strong oxidizing agents liberate chlorine from acidified solutions of sodium chloride. The solubility of the antimicrobial preservative methylparaben is decreased in aqueous sodium chloride solutions and the viscosity of carbomer gels and solutions of hydroxyethyl cellulose or hydroxypropyl cellulose is reduced by the addition of sodium chloride. 

Discovery of the formation of liquid crystalline solutions by cellulosics in the mid-1970s has resulted in attempts to develop new cellulosics products with properties superior to those of conventional cellulosic. Following the first observation of mesophases formed in aqueous solutions of hydroxypropyl cellulose (HPC), a variety of other cellulose derivatives have been reported to form liquid crystals. Liquid crystalline solutions of cellulose and its derivatives provide a potential route to high-modulus and high-tenacity cellulosic fibers, films, and other high-performance products. 

Nishio, Y. Yamane, Y. Takahashi, T. Morphological studies of liquid-crystalline cellulose derivatives. II. Hydroxypropyl cellulose films prepared from liquid-crystalline aqueous solutions. J. Polym. Sci. Polym. Phys. Ed. 1985, 23 (5), 1053-1064. 

Chiba, R. Nishio, Y. Miyashita, Y. Electroopti-cal behavior of liquid-crystalline (hydroxypropyl)-cellulose/inorganic salt aqueous solutions. Macromolecules 2003, 36 (5), 1706-1712. 

The flow through an abrupt contraction " or a step stenosis was demonstrated. The flow of liquid crystalline hydroxypropyl cellulose aqueous solutions, where polymer was flowing through an abrupt contraction, was imaged by pulsed field gradient NMR techniques. Flow velocity was determined in the case of the flow through step stenosis. ... 

Nakai et al. (175) studied the sterically stabilized silica suspension in aqueous hydroxypropyl(methyl)cellulose solution (HPMC). They confirmed, in part, the results of Otsubo (171) that both shear thinning... 

Ma L, Kang HL, Liu RG, Huang Y (2010) Smart assembly behaviors of hydroxypropyl-cellulose-grq/i -poly(4-vinyl pyridine) copolymers in aqueous solution by thermo and pH stimuli. Langmuir 26 18519-18525... 

Guido S. Phase behavior of aqueous solutions of hydroxypropyl cellulose. Macromolecules 1995 28 4530-4539. 

Hypromellose or hydroxypropylmethylcellulose is a partly O-methylated and 0-(2-hydroxypropylated) cellulose [25]. It is used from 10% up to 80% w/w for controlled drug release in solid dosage form and from 2% to 20% w/w as coating solution for tablets and pellets [25,30,31 ]. Hydroxypropylmethylcellulose is a nonionic polymer with pH of a 2% w/w aqueous solution ranging from 5 to 8. It is soluble in water. Being nonionic, it will not form complexes with metallic salts or ionic compounds that can possibly lead to the precipitation of insoluble compounds [32]. Hydroxypropylmethylcellulose matrix hydrates and swells into a gel layer in the direction of matrix surfaces to core when it is contacted with the dissolution medium [14,20,33]. Erosion of gel takes place thereafter and may occur simultaneously with the subsequent phases of matrix hydration and swelling [14]. The swelling and erosion properties of a solid matrix made of... 

Another example of the phase behavior of asymmetric molecules is given in Fig. 3.22 for aqueous solutions of hydroxypropyl cellulose.(97) The phase diagram for this system shows all of the major features expected from the Rory theory for an asymmetric polymer solute. The slight tilting of the narrow biphasic region could possibly be attributed to some molecular flexibility as well as anisotropic interac-tion.(98) The phase diagram for the ternary system, polymer and two solvents, for poly(p-phenylene terephthalamide) also shows the major features expected from theory. (99)... 

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