Journal of Oil Palm Research Vol.  August 2012 p.  1361-1367

Characterisation of palm-based polyols by gel permeation chromatography with combined detectors


Gel permeation chromatography (GPC) with combined detectors, i.e. differential refractive index (DRI) and viscometer, was used to analyse molecular weight averages of palm-based polyol samples (POP Pioneer 100 and POP Pioneer derivatives, three types of POP Primer and a POP Premier). Elution was carried out using tetrahydrofuran as the mobile phase at 30°C at a flow rate of 1 ml min-1 on a PLgel Mixed D column. Narrow molecular weight distribution (MWD) polystyrene was used as the calibration standard to generate a universal calibration for quantification of the absolute molecular weight (MW) averages and MWD.

POP Pioneer 100 was found to have a number average molecular weight (Mn) ranging from 1861 to 2800 Daltons, a weight-average molecular weight (Mω) of 10 600 to 18 000 Daltons and polydispersity index (PDI) of 5.5 to 6.5 with a broad bimodal MWD. POP Pioneer derivatives had Mn ranging from 2500-2700 Daltons, Mw from 27 110-30 500 Daltons, PDI from 10.2-11.6 and a broad bimodal MWD. POP Premier had Mn from 1290-2215 Daltons, Mw from 17 700-21 500 Daltons and PDI from 7.8-16.7 with broad bimodal MWD. All three types of POP Primer showed close values of MW average with Mn between 1800 and 1900 Daltons, Mw from 7700-7900 Daltons, PDI from 3.8-4.2 and with a skewed bimodal MWD. The Mark-Houwink plots of palm-based polyols showed that the changes in their structures were insignificant over the range of MWD, except for POP Primer Types 2 and 3 where branching was more obvious at the higher end of the molecular weight.

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Author Information
* Malaysian Palm Oil Board, P. O. Box 10620, 50720 Kuala Lumpur, Malaysia.

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