17.3.3.5 Computer The computer automatically calculates, records, and report numerical values for Mn, Mw, Mv, Mz, Mz+1, and the MWD. It can also provide complete control of GPC systems so that large numbers of samples can be run unattended and raw data can be automatically processed. Nowadays, the software used in GPC should be capable of providing special calculations for multidetection processing, special calibration routines, polymer branching, and intrinsic viscosity determination, etc. SEC can be used as a measure of both the size and the MW dispersity of a polymer; that is, it has the capability of finding the distribution of the sizes of polymer molecules. If standards of a known size are run previously, then a calibration curve can be created to determine the sizes of polymer molecules of interest in the solvent chosen for analysis often tetrahydrofuran (THF). Alternatively, techniques such as light scattering and/or viscometry, which do not rely on the calibration using standards of known MW, can be used online with SEC to yield absolute MWs. Because of the difference in size of two different polymers
with identical MWs, the absolute determination methods are, in general, more desirable.
17.3.3.5 Computer The computer automatically calculates, records, and report numerical values for Mn, Mw, Mv, Mz, Mz+1, and the MWD. It can also provide complete control of GPC systems so that large numbers of samples can be run unattended and raw data can be automatically processed. Nowadays, the software used in GPC should be capable of providing special calculations for multidetection processing, special calibration routines, polymer branching, and intrinsic viscosity determination, etc. SEC can be used as a measure of both the size and the MW dispersity of a polymer; that is, it has the capability of finding the distribution of the sizes of polymer molecules. If standards of a known size are run previously, then a calibration curve can be created to determine the sizes of polymer molecules of interest in the solvent chosen for analysis often tetrahydrofuran (THF). Alternatively, techniques such as light scattering and/or viscometry, which do not rely on the calibration using standards of known MW, can be used online with SEC to yield absolute MWs. Because of the difference in size of two different polymerswith identical MWs, the absolute determination methods are, in general, more desirable.
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