A new procedure for calibrating ThFFF systems by using broad molecular weight standards based on a non-linear least squares fitting of the fractogram to the Molecular Weight Distribution to derive the system calibration parameters is presented and explored by simulation. This procedure proved robust with respect to noise and it is able to account for detector nonlinearity. The effect of band broadening was evaluated and it was found that significant bias is observed only for polydispersities lower than 1.3. The method was experimentally validated by using polystyrene in decalin and was then applied to polypropylene under conditions of high temperature ThFFF (Tc = 394 K). It appears that the presented method can be useful in characterising polyolefins polymers for which monodisperse standards are not available.
Calibration in Thermal Field Flow Fractionation with Polydisperse Standards: Application to Polyolefin characterization
PASTI, Luisa;CONTADO, Catia;DONDI, Francesco;
2002
Abstract
A new procedure for calibrating ThFFF systems by using broad molecular weight standards based on a non-linear least squares fitting of the fractogram to the Molecular Weight Distribution to derive the system calibration parameters is presented and explored by simulation. This procedure proved robust with respect to noise and it is able to account for detector nonlinearity. The effect of band broadening was evaluated and it was found that significant bias is observed only for polydispersities lower than 1.3. The method was experimentally validated by using polystyrene in decalin and was then applied to polypropylene under conditions of high temperature ThFFF (Tc = 394 K). It appears that the presented method can be useful in characterising polyolefins polymers for which monodisperse standards are not available.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
