Presented at the 4th International Conference on Polyolefin Characterization (ICPC), 2012. The Woodlands, TX, USA.
Pilar del Hierro, Jesús Montesinos, Rubén Tarín, Benjamín Monrabal. Polymer Char, Valencia, Spain.
Significant engineering efforts have been made in recent years to bring high-temperature GPC analysis to a modern, reliable, and automated task, and with enough sensitivity for accurate analysis of the Molar Mass Distribution (MMD) through the use of Infrared (IR) detectors, which provide a stable baseline in concentration and have the capability to perform simultaneous composition – molar mass interdependence analysis.
Developments in Infrared detection have allowed the design of an integrated IR detector – IR5 – with 10 times improvement in sensitivity over the existing IR4 detector of the GPC-IR instrument. This development allows for the use of lower sample concentrations (required very often to prevent viscous fingering effects in the analysis of high molar mass resins) and provides better sensitivity to measure low levels of branch content simultaneously (pipe resins).
The new detector, using a Mercury Cadmium Telluride detector (a modified integrated version of the well known IR5 MCT detector), is thermoelectrically cooled and it has been integrated into the existing GPC-IR instrument without demanding external blocks or heating interfaces.
The IR5 MCT allows the analysis of high Molecular Weight resins without overloading the GPC/SEC columns, and achieves excellent composition sensitivity for branching measurement in pipe resins.
Together with the IR5 MCT, the IR4 detector is presented showing the performance in composition analysis in Ethylene-Propylene copolymers. The IR4 can be used with a carbonyl sensor for composition-molar mass interdependence in carbonyl/ester/acid ethylene copolymers.
Applications of GPC-IR with IR4 and IR5 MCT are presented.