Presented at the 4th International Conference on Polyolefin Characterization (ICPC), 2012. The Woodlands, TX, USA.
Carolina Ruiz-Orta, M. Belén Mula Andrés. Repsol, Madrid, Spain.
Alberto Ortín, Benjamín Monrabal. Polymer Char, Valencia, Spain.
Short-chain Branching (SCB) along the Molar Mass Distribution (MMD) of polyolefins is determined by coupling a High Temperature Gel Permeation Chromatograph (HT-GPC) to FTIR or filter-based IR detectors.
Modern filter-based IR detectors prove to have similar sensitivity towards SCB frequency to that of FTIR detectors while also having some practical advantages, which are here reviewed. The good chromatographic behaviour of filter-based IR detectors allows using one of the detector channels as primary mass detector for acquiring the molar mass distribution, resulting in a more accurate and precise compositional – molar mass interdepence description. The operational principles of both techniques are outlined, as well as the calibration procedures typically followed in each case.
A set of selected polyethylene test samples have been analysed by FTIR and by an IR5 MCT filter-based detector coupled to a high-temperature gel permeation chromatograph. Raw and processed data is compared, as well as analytical conditions, and measured data quality and uncertainty.