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Mark–Houwink Equation
The Mark–Houwink equation, also known as the Mark–Houwink–Sakurada equation or the Kuhn–Mark–Houwink–Sakurada equation or the Landau–Kuhn–Mark–Houwink–Sakurada equation or the Mark-Chrystian equation gives a relation between intrinsic viscosity eta/math> and molecular weight M: :etaKM^a From this equation the molecular weight of a polymer can be determined from data on the intrinsic viscosity and vice versa. The values of the Mark–Houwink parameters, a and K, depend on the particular polymer-solvent system. For solvents, a value of a=0.5 is indicative of a theta solvent. A value of a=0.8 is typical for good solvents. For most flexible polymers, 0.5\leq a\leq 0.8. For semi-flexible polymers, a\ge 0.8. For polymers with an absolute rigid rod, such as Tobacco mosaic virus, a=2.0. It is named after Herman F. Mark and Roelof Houwink. Applications In size-exclusion chromatography, such as gel permeation chromatography, the intrinsic viscosity of a polymer is direct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrinsic Viscosity
Intrinsic viscosity \left \eta \right/math> is a measure of a solute's contribution to the viscosity \eta of a solution. It should not be confused with inherent viscosity, which is the ratio of the natural logarithm of the relative viscosity to the mass concentration of the polymer. Intrinsic viscosity is defined as : \left \eta \right= \lim_ \frac where \eta_0 is the viscosity in the absence of the solute, \eta is (dynamic or kinematic) viscosity of the solution and \phi is the volume fraction of the solute in the solution. As defined here, the intrinsic viscosity \left \eta \right/math> is a dimensionless number. When the solute particles are rigid spheres at infinite dilution, the intrinsic viscosity equals \frac, as shown first by Albert Einstein. In practical settings, \phi is usually solute mass concentration (c, g/dL), and the units of intrinsic viscosity \left \eta \right/math> are deciliters per gram (dL/g), otherwise known as inverse concentration. Formulae for ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gel Permeation Chromatography
Gel permeation chromatography (GPC) is a type of size-exclusion chromatography (SEC), that separates analytes on the basis of size, typically in organic solvents. The technique is often used for the analysis of polymers. As a technique, SEC was first developed in 1955 by Lathe and Ruthven.Lathe, G.H.; Ruthven, C.R.J. The Separation of Substance and '1956', ''62'', 665–674. The term ''gel permeation chromatography'' can be traced back to J.C. Moore of the Dow Chemical Company who investigated the technique in 1964. The proprietary column technology was licensed to Waters Corporation, who subsequently commercialized this technology in 1964.Moore, J.C. Gel permeation chromatography. I. A new method for molecular weight distribution of high polymers. ''J. Polym. Sci.'', 1964, ''2'', 835-84 GPC systems and consumables are now also available from a number of manufacturers. It is often necessary to separate polymers, both to analyze them as well as to purify the desired product. When cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toluene
Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) attached to a phenyl group. As such, its systematic IUPAC name is methylbenzene. Toluene is predominantly used as an industrial feedstock and a solvent. As the solvent in some types of paint thinner, permanent markers, contact cement and certain types of glue, toluene is sometimes used as a recreational inhalant and has the potential of causing severe neurological harm. History The compound was first isolated in 1837 through a distillation of pine oil by the Polish chemist Filip Walter, who named it ''rétinnaphte''. In 1841, French chemist Henri Étienne Sainte-Claire Deville isolated a hydrocarbon from balsam of Tolu (an aromatic extract from the tropical Colombian tree ''Myroxylon balsamum''), which Deville recognized as similar to Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polystyrene
Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It is a poor barrier to oxygen and water vapour and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several million tonnes per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and in the jewel cases used for storage of optical discs such as CDs and occasionally DVDs), containers, lids, bottles, trays, tumblers, disposable cutlery, in the making of models, and as an alternative material for phonograph records. As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calibration Curve
In analytical chemistry, a calibration curve, also known as a standard curve, is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration. A calibration curve is one approach to the problem of instrument calibration; other standard approaches may mix the standard into the unknown, giving an internal standard. The calibration curve is a plot of how the instrumental response, the so-called analytical signal, changes with the concentration of the analyte (the substance to be measured). General use In more general use, a calibration curve is a curve or table for a measuring instrument which measures some parameter indirectly, giving values for the desired quantity as a function of values of sensor output. For example, a calibration curve can be made for a particular pressure transducer to determine applied pressure from transducer output (a voltage). Such a curve is typically us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Of Best Fit
Line fitting is the process of constructing a straight line that has the best fit to a series of data points. Several methods exist, considering: *Vertical distance: Simple linear regression In statistics, simple linear regression is a linear regression model with a single explanatory variable. That is, it concerns two-dimensional sample points with one independent variable and one dependent variable (conventionally, the ''x'' and ... **Resistance to outliers: Robust simple linear regression * Perpendicular distance: Orthogonal regression **Weighted geometric distance: Deming regression * Scale invariance: Major axis regression See also * Linear least squares * Linear segmented regression * Linear trend estimation * Polynomial regression * Regression dilution Further reading *"Fitting lines", chap.1 in LN. Chernov (2010), ''Circular and linear regression: Fitting circles and lines by least squares'', Chapman & Hall/CRC, Monographs on Statistics and Applied Probabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elution
In analytical and organic chemistry, elution is the process of extracting one material from another by washing with a solvent; as in washing of loaded ion-exchange resins to remove captured ions. In a liquid chromatography experiment, for example, an analyte is generally adsorbed, or "bound to", an adsorbent in a liquid chromatography column. The adsorbent, a solid phase (stationary phase), is a powder which is coated onto a solid support. Based on an adsorbent's composition, it can have varying affinities to "hold" onto other molecules—forming a thin film on the surface of its particles. Elution then is the process of removing analytes from the adsorbent by running a solvent, called an "eluent", past the adsorbent/analyte complex. As the solvent molecules "elute", or travel down through the chromatography column, they can either pass by the adsorbent/analyte complex or they can displace the analyte by binding to the adsorbent in its place. After the solvent molecules displa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Size-exclusion Chromatography
Size-exclusion chromatography (SEC), also known as molecular sieve chromatography, is a chromatographic method in which molecules in solution are separated by their size, and in some cases molecular weight. It is usually applied to large molecules or macromolecular complexes such as proteins and industrial polymers. Typically, when an aqueous solution is used to transport the sample through the column, the technique is known as gel-filtration chromatography, versus the name gel permeation chromatography, which is used when an organic solvent is used as a mobile phase. The chromatography column is packed with fine, porous beads which are commonly composed of dextran, agarose, or polyacrylamide polymers. The pore sizes of these beads are used to estimate the dimensions of macromolecules. SEC is a widely used polymer characterization method because of its ability to provide good molar mass distribution (Mw) results for polymers. Applications The main application of gel-filtration chr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Weight
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and biochemistry, the distinction from ions is dropped and ''molecule'' is often used when referring to polyatomic ions. A molecule may be homonuclear, that is, it consists of atoms of one chemical element, e.g. two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, e.g. water (two hydrogen atoms and one oxygen atom; H2O). In the kinetic theory of gases, the term ''molecule'' is often used for any gaseous particle regardless of its composition. This relaxes the requirement that a molecule contains two or more atoms, since the noble gases are individual atoms. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are typically not consi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roelof Houwink
Roelof Houwink (1897–1988) was a Dutch polymer scientist, educated at the University of Delft. He worked at Phillips since 1925. From 1939 to 1956 he was director-general of the TNOs ''Rubberinstituut'' in Delft.Gary Patterson, "Polymer Science from 1935 to 1953: Consolidating the Paradigm", Springer 2014, S. 64f The Mark-Houwink equation is named after him together with Herman F. Mark. Publications *''Elasticity, Plasticity and Structure of Matter'', 1937, Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambridge University Pre ..., London References Polymer scientists and engineers 20th-century Dutch chemists Delft University of Technology alumni 1897 births 1988 deaths {{Netherlands-scientist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Herman F
Herman may refer to: People * Herman (name), list of people with this name * Saint Herman (other) * Peter Noone (born 1947), known by the mononym Herman Places in the United States * Herman, Arkansas * Herman, Michigan * Herman, Minnesota * Herman, Nebraska * Herman, Pennsylvania * Herman, Dodge County, Wisconsin * Herman, Shawano County, Wisconsin * Herman, Sheboygan County, Wisconsin Place in India * Herman (Village) Other uses * ''Herman'' (comic strip) * ''Herman'' (film), a 1990 Norwegian film * Herman the Bull, a bull used for genetic experiments in the controversial lactoferrin project of GenePharming, Netherlands * Herman the Clown ( fi, Pelle Hermanni), a Finnish TV clown from children's TV show performed by Veijo Pasanen * Herman's Hermits, a British pop combo * Herman cake (also called Hermann), a type of sourdough bread starter or Amish Friendship Bread starter * ''Herman'' (album) by 't Hof Van Commerce See also * Hermann (other) * Arman ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
