Page 125 - Carrahers_Polymer_Chemistry,_Eighth_Edition

88 Carraher’s Polymer Chemistry

High-performance liquid chromatography (HPLC): Chromatography in which pressure is
applied that causes the solution to pass more rapidly through the column.
Hildebrand (H): Unit used for solubility parameter values.
Ion-exchange chromatography: Chromatography that separates molecules on the basis of their
electrical charge employing polyanionic or polycationic resins.
Kauri-Butanol values: Measure of the aromaticity of a solvent.
Low-angle laser light-scattering photometry (LALLS): Light scattering that employs low-
angle measurements minimizing the effect of polymer shape on the scattering.
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Mark–Houwink equation: Relates limiting viscosity number to molecular weight; LVN = KM .
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS): Mass spec-
trometry in which the sample is placed in a matrix that contains a strong UV absorber
chosen to match the UV absorption of the laser, which allows the molecules to become
volatilized with minimal fragmentation.
Melt index: Measure of the flow related inversely to melt viscosity.

Monodisperse: System containing molecules of only one chain length.
Multiangle low-angle laser light-scattering photometry (MALS): Similar to LALLS except
where the necessary angle ratios are made together; employs low-angle measurements
minimizing the effect of polymer shape on the scattered light.
Number-average molecular weight: Arithmetical mean value obtained by dividing the sum of
the molecular weights by the number of molecules.
Oligomer: Polymers with 2–10 repeat units. Oligos means “few.”
Osmometry: Gives number-average molecular weight from osmotic pressure measurements.
Polydisperse: Mixture of polymer chains of different lengths.
Raoult’s law: States that the vapor pressure of a solvent in equilibrium with a solution is equal
to the product of the mole fraction of the solvent and the vapor pressure of the pure solvent.
This relationship is used in obtaining number-average molecular weights.
SEC-MALS and SEC-LALLS: Coupled chromatography and light-scattering photometry
that allows the determination of a number of important values along with chain length
distribution.
Sedimentation equilibrium experiment: Ultracentrifugation technique that allows chain
length information to be determined.
Semipermeable membrane: Membrane that permits the diffusion of solvent molecules but not
large molecules.
Size exclusion chromatography (SEC): Chromatography in which separation is by molecular
size or differences in hydrodynamic volume: also called gel permeation chromatography
(GPC); can use the universal calibration approach to obtain molecular weight.
Solubility parameter: A numerical value equal to the square root of the CED, which is used
to predict polymer solubility.
Theta solvent: Solvent in which the polymer chain exists as a statistical coil.
Theta temperature: Temperature at which a polymer of infinite molecular weight begins to

precipitate.
Ultracentrifuge: Centrifuge that increases the force of gravity by as much as 100,000 times
causing a distribution of materials in a solution to separate in accordance with chain
length.
Vapor pressure osmometry: Technique for determining number-average molecular weight by
measuring the relative heats of evaporation of a solvent form a solution and pure solvent.
Viscosity: Resistance to fl ow.
Intrinsic viscosity: The limiting viscosity number obtained by extrapolation of the reduced
viscosity to zero concentration.

Reduced viscosity: Specific viscosity divided by the polymer concentration.
Relative viscosity: Ratio of the viscosities of a solution and its solvent.

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