Free volume effects on dissolution of poly (methyl methacrylate)

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National Library of Canada , Ottawa
SeriesCanadian theses = Thèses canadiennes
The Physical Object
FormatMicroform
Pagination1 microfiche.
ID Numbers
Open LibraryOL19310003M
ISBN 100315566914
OCLC/WorldCa25553076

Nomenclature M N number average molecular weight M W weight average molecular weight x AB Flory–Huggins interaction parameter V ref reference volume d i solubility parameter of species i R gas constant T absolute temperature DG m Gibbs free energy change on mixing DH m enthalpy change on mixing DS m entropy change on mixing V mix volume of the mixture DEV i energy of vaporization of.

The is a factor which is necessary to preserve the Flory form of the chemical potential expression. The most likely origin of this correction term lies in so-called free volume effects that are neglected in the Flory–Huggins treatment.

In the liquid state, the motion and vibrations of the molecules lead Free volume effects on dissolution of poly book density fluctuations, or free Cited by:   Effect of Temperature on the Free Volume in Glassy Poly(ethylene terephthalate) B. Wang, Z. Wang, M. Zhang, W.

Liu, and S. Wang Macromolecules 35 (10), Cited by: Abstract Polymer dissolution in solvents is an important area of interest in polymer science and engineering because of its many applications in industry such as microlithography, membrane science, plastics recycling, and drug delivery.

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Unlike non-polymeric materials, polymers do not dissolve instantaneously, and the dissolution is controlled by either the disentanglement of the polymer chains. Further investigation was focused on the effect of sample history through successive recycling cycles.

This recycling option is currently the most effective way to reduce the volume of organic material which, due to a lack of other recycling possibilities, may then be ended in landfilling disposal. In the literature results are referred Cited by: The dissolution rate is not only affected by nature of the diluent but also affected by excipient dilution (drug/excipient ratio).

E.g. in quinazoline comp. dissolution rate increases as t he excipient /drug ratio increases from to to The only limitation for the volume of dissolution medium is that the expected amount of test drug must be freely soluble in the volume at 37 ºC.

It is possible that the drug may not be soluble at room temperature, but at 37 ºC it may be freely soluble.

Details Free volume effects on dissolution of poly (methyl methacrylate) EPUB

In such situations, for dissolution testing purposes, the drug will be considered as freely. Volume of dissolution medium. If the volume of the dissolution medium is small, C can rapidly increase during dissolution and approach C S. If the volume is large, then C may be negligible with respect to C S and thus ‘sink’ conditions will operate.

This can be controlled in vitro but must be taken into account in vivo as the volume of the. Mechanism of recrystallization that effects on dissolution rate. bit eye model using biodegradable poly beta 29 Hydrophobicity of the drug is increased when "G-1" is in its free acid form.

tion can be used to represent the three steps of dissolution described above, keep ­ ing the system isothermal. Using Figurestep one of the dissolution scheme, breaking of the solute lattice to free a solute particle, can be represented with ∆ H.

and ∆ S. This action increases enthalpy but decreases entropy (∆ H ↑, ∆ S ↓). Furthermore, the effect of compositions of the solvent mixtures on the dissolution rates is a result of two opposite effects: (i) the ability of the polymer to be swelled (CCl4 fraction) and (ii.

different physical concepts such as obstruction effects, free volume effects and hydrodynamic interactions. With the availability of pulsed field gradient NMR techniques and other modern experimental methods, the study of diffusion has become much easier and data on diffusion in polymers have become more available.

Okubo and T. Kusano, Production of polymer microparticles by?dissolution. of submicron-sized water-insoluble ionized carboxylated polymer particles in the presence of various nonionic emulsifiers, Colloid & Polymer Science, /BF,12, (), ().

When does it make sense to perform a volume correction for the decrease in dissolution medium of multiple point dissolutions.

I checked the it mentioned " where it can be shown that replacement of the medium is not necessary, correct for the volume change in the calculation." Should you be correcting if the total volume changed by 1% or if the change in % potency from theory.

When the effect of the particle size distribution was neglected, the theoretical curve underestimated the observed value at the early phase of dissolution process. When the diffusion coefficient of a free drug was used instead of the effective diffusion coefficient, the.

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Mixing Tank for Dissolution of Dry Polymer Patented Hollow-Wing Impeller No Weissenberg Effect Large Impeller, d/D > Uniform Mixing Energy Low RPM, 60 - rpm Low-intensity Mixing Minimize Damage to Polymer Chain Square Tank Design No Wessenberg Effect No Baffles Needed, No Dead Zone Shorter Mixing Time – Due to DD4.

Volume of dissolution medium; If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Dissolution rate of single crystal of sulphathiazole was found to decrease significantly in presence of FD&C Blue No The inhibiting effect was related to preferential adsorption of dye molecules on primary dissolution sources of crystal surfaces.

They inhibit the micellar solubilization effect of bile salts on drug. Plasticizers increase the free volume by spacing polymer chains and the mobility of the chain segments, resulting in a decrease in the Tg and melt viscosity [ 35 ]. The lignin plasticization will also contribute to improving the dispersion of lignin in polymer matrices [ 26] and the processability and toughness of the thus-obtained composite.

The objective of this study was to investigate the effect of aqueous film coating on MCHC tablets evaluated by comparison with plain MCHC tablets and non-aqueous coated tablets.

The parameters evaluated were the film smoothness, shininess, coating uniformity, percentage weight increase, hardness, disintegration time, dissolution study, moisture.

Description Free volume effects on dissolution of poly (methyl methacrylate) PDF

The Ideal Dissolution Media • Meets sink conditions • Simple preparation • Drug is Stable in media 24 hrs+ • Uses as little extras as possible – Surfactants – Alcohol • Biologically relevant for site of dissolution in vivo – IR typically in acid – DR typically in acid, then neutral –.

Title:Development of Itraconazole Liquisolid Compact: Effect of Polyvinylpyrrolidone on the Dissolution Properties VOLUME: 13 ISSUE: 3 Author(s):Wei Gong, Yuli Wang, Lei Sun, Jiahui Yang, Li Shan, Meiyan Yang and Chunsheng Gao Affiliation:Beijing Institute of Pharmacology and Toxicology, BeijingChina.

Keywords:Dissolution, itraconazole, liquisolid compact, N-methylpyrrolidone, PVP. The effect of alkyl chain length on the cellulose dissolution ability was acknowledged already by Swatloski and has since then been observed by several groups [].

Studies on the imidazolium cation itself, not taking into account its properties as a solvent, recently explained in detail the effect of cation symmetry and found effects.

the dissolution media is a ve r y effe ct i v e way to i n c r ease es of solubility as a func-tion of pH for a free base and a free acid are show n in Fi g u r e defines an int r insic solubility (Ci) as the solubility of the neutral co m po u n pHs a. Effect of chain rigidity on block copolymer micelle formation and dissolution as observed by 1H-NMR spectroscopy.

Microcapsules were made by varying the composition of the polymers in polyblend to study the effect on encapsulation efficiency, surface properties and in vitro dissolution test at pH and pH The microcapsules were all spherical and had a smooth surface as. The partition coefficient (pK a) of NS isand its solubility depends upon the pH of the dissolution l was incorporated into medium A (30% v/v ethanol and 70% v/v hydrochloric acid buffer pH ) to compensate for the low solubility of NS at acidic pH (7,9).Twenty-five milligrams of spray-dried (SD) complex was dissolved in ml of the medium A with constant stirring for 24 h.

The drug dissolution rate is an amount of a solid dosage form that goes into solution in a certain amount of time. In the dissolution test, the drug solubility is the main parameter that affects the rate of dissolution.

The poor dissolution rates of poorly water soluble drugs are still a challenge in the pharmaceutical industry [12, 13].

One-pot free-radical polymerization of N-acryloyl glycinamide in the presence of hyaluronic acid as transfer-termination agent led to new copolymers in high yields without any chemical activation of hyaluronic acid before.

All the copolymers formed thermoresponsive hydrogels of the Upper Critical Solution Temperature-type in aqueous media. Gel properties and the temperature of the reversible.

Title:Development of a Suitable Dissolution Method for the Combined Tablet Formulation of Atorvastatin and Ezetimibe by RP-LC Method VOLUME: 13 ISSUE: 3 Author(s):Kose Ozkan Cansel, Esim Ozgur, Kurbanoglu Sevinc, Savaser Ayhan, Ozkan Sibel A and Ozkan Yalcin Affiliation:Gulhane Military Medical Academy, Department of Pharmaceutical Technology, Etlik, Ankara, Turkey.for permeation rate based on the free volume theory has been proposed.

PVA gel membranes with various mesh sizes were prepared by chemical cross- linking. The effects of solute size, solute hydrophili- city and water volume fraction, H, on the normalized .Poly(vinyl alcohol) (PVA) is a water soluble polymer whose water solubility depends on its degree of hydrolysis, molecular weight, and tendency to hydrogen bond in aqueous solutions.

PVA exhibits both upper and lower critical solubility temperatures and can be readily solubilized in water.