RESEARCH ARTICLE

Journal of Oil Palm Research Vol. 24 (2) August 2012, p. 1361-1367

CHARACTERISATION OF PALM-BASED POLYOLS BY GEL PERMEATION CHROMATOGRAPHY WITH COMBINED DETECTORS

BONNIE TAY YEN PING*; NURUL’ AIN HANZAH* and HOONG SENG SOI*

ABSTRACT

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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* Malaysian Palm Oil Board,
P. O. Box 10620, 50720 Kuala Lumpur,
Malaysia.
E-mail: bonnie@mpob.gov.my