INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
RANDOMLY-BRANCHED POLYMERS BY SIZE EXCLUSION CHROMATOGRAPHY WITH TRIPLE DETECTION: COMPUTER SIMULATION STUDY ON BIASED IN DISTRIBUTION OF MOLAR MASSES AND DEGREE OF BRANCHING
Autor/es:
CLEMENTI, LUIS A.; VEGA, JORGE R.; MEIRA, GREGORIO R.
Lugar:
Porec
Reunión:
Simposio; 19th International Symposium on Separation Sciences. New Achievement in Chromatography; 2013
Institución organizadora:
Croatian Society of Chemical Engineers
Resumen:
This article theoretically evaluates the biases introduced into the distributions of molar masses (MMD) and number of long chain branches per molecule (LCBD), when randomly-branched polymers are analyzed by size exclusion chromatography (SEC) with light scattering and specific viscosity detectors. The MMDs of fractions containing from 0 to up to 75 tetrafunctional branch units per molecule were calculated with the Stockmayer equation (1); and the calibrations of the branched classes were estimated from an imposed calibration for the linear class combined with appropriate contraction factors. An ideal SEC model was simulated that assumes perfect fractionation by hydrodynamic volume, except for a minor mixing in the detector cells. Under these ideal conditions, the MMD exhibits a negligible bias; with a maximum local dispersity of 1.0035 at the high molar masses. These results are in accord with previous investigations (2, 3), but differ quantitatively from the observations in Ref. (4). When introducing band broadening in the column while maintaining perfect noise-free chromatograms, then the MMD still remains essentially unbiased. However, rather poor MMD estimates are obtained when even minor zero-mean random noises are added onto the chromatograms. Only gross estimates of the LCBD are possible due to theoretical uncertainties, to errors in the required physico-chemical parameters, and to a fast propagation of errors caused by the highly nonlinear nature of the problem. The work was carried out under the auspices of the IUPAC project: ?Data Treatment in SEC and Other Techniques of Polymer Characterization. Correction for Band Broadening and Other Sources of Error?, Chair G. Meira, http://www.iupac.org/web/ins/2009-019-2-400.