The intrinsic viscosity is used to classify polymers and helps to identify the applications that specific polymers can be used for. Depending on the type of monomer, the size and molecular structure of the polymer molecule, polymers show unique properties.
Viscosity of Polymer Solutions Part I: Intrinsic Viscosity of Dilute Solutions High molecular weight polymers greatly increase the viscosity of liquids in which they are dissolved. The increase in viscosity is caused by strong internal friction between the randomly coiled and swollen macromolecules and the surrounding solvent molecules.
How much a polymer increases the viscosity of a solvent will depend on both the nature of the polymer and solvent. Three important quantities frequently encountered in the field of polymer solution rheology are the relative viscosity, the specific and reduced specific viscosity.
These quantities are defined as follows: Assuming the polymers are spherical impenetrable particles, the increase in viscosity can be calculated with Einstein's viscosity relationship: It has been shown that the equation is still applicable to dissolved polymers if the hard sphere radius is replaced by the hydrodynamic radius of the polymer coil.
The equation is known as the Flory-Fox equation. Mark-Houwink parameters have been tabulated for a large number of polymer-solvent systems in standard references.
To estimate the molecular weight, the viscosity of both the solvent and the solution have to be measured. A measurement with an Ubbelohde capillary viscometer yields following results: Grulke, Polymer Handbook, 4th ed.
Thus, this quantity describes the effect of completely separated polymer chains on the solution viscosity. Mark-Houwink Relation The viscosity of very dilute polymer solutions can be described with a simple power law, known as the Mark-Houwink relation.
The Mark-Houwink parameters can be determined from a double logaritmic plot of intrinsic viscosity versus molecular weight which yields straight lines. Gel permeation chromatography GPC is frequently used to measure the molecular weight distribution of a polymer sample. The retention time of a polymer in a GC column is directly proportional to its size.
Thus a GPC seperates dissolved polymers by their hydrodynamic volume. A GPC chromatogram provides the molecular weight distribution of a polymer sample because the hydrodynamic volume of a polymer particle is directly related to the molecular weight.Sadao Hirota, in Methods in Enzymology, Determination of Nondimensional Intrinsic Viscosity.
η] is determined blog-mmorpg.com there is little inner aqueous phase in lipoplex, φ can be regarded to be φ blog-mmorpg.comd viscosity, η red = η sp ⧸φ net, is then plotted against φ net. φ net is calculated by from the amount of DNA and lipids in the sample. Although ρ of .
The intrinsic viscosity number is defined as the limiting value of the specific viscosity/concentration ratio at zero concentration.
Intrinsic viscosity is determined by. Oct 01, · An equation derived by Han relating intrinsic visocity to molecular weight of a polymer has been fitted to experimental data over a large range of molecular weight.
This procedure is used to determine the intrinsic viscosity (IV) of the material. IV is a measure of the Molecular Weight (MW) of PET. The properties of PET are better at higher MW (higher IV) and worse at lower MW (lower IV). Summary Intrinsic Viscosity. is a measure for the internal friction in polymer solutions at the limit of zero polymer concentration.
Thus, this quantity describes the effect of completely separated polymer chains on the solution viscosity. Intrinsic Viscosity (IV) is a measure of the molecular weight of the polymer and reflects the melting point, crystallinity and tensile strength of the material.
The value of IV as part of the specification to determine the grade of PET to be used.