Absolute molecular weight’s measurements of synthetic polymers using the Viscotek SEC-MALS 20
The molecular weight, molecular weight distribution and size of two common polymers are measured using SEC-MALS 20. Results from SEC-MALS and conventional calibration are compared and discussed.
Absolute molecular weight’s measurements of synthetic polymers using the Viscotek SEC-MALS 20
The molecular weight, molecular weight distribution and size of two common polymers are measured using SEC-MALS 20. Results from SEC-MALS and conventional calibration are compared and discussed.
Introduction
The physical properties and behavior of polymers depends strongly on the properties of the polymer molecules themselves. Molecular weight and molecular weight distribution, molecular size and structure all affect how the material will behave. Gel-permeation chromatography (GPC), also called size-exclusion chromatography (SEC), is the most commonly used tool for assessing these parameters.
The principle of GPC involves separating the sample as it travels through a porous but inert column matrix. While smaller molecules penetrate the pores more deeply, larger molecules are excluded and thus travel through the column faster. The result is a separation based on hydrodynamic volume but the desire is to know the molecular weight of the sample.
The Malvern SEC-MALS 20 system is a 20 angle light scattering detector capable of making measurements of molecular weight and Rg (radius of gyration). It is used as part of a multi-detector GPC system that combines light scattering with other detectors such as refractive index (RI), ultraviolet (UV) and intrinsic viscosity (IV) to generate a large amount of information about a sample simultaneously.
