Presented at the 4th International Conference on Polyolefin Characterization (ICPC), 2012. The Woodlands, TX, USA.
Esther López, Alberto Ortín, Jesús Montesinos. Polymer Char, Valencia, Spain.
The solvent choices for use in High Temperature GPC/SEC of polyolefins are limited. The most common solvents used are 1,2,4-trichlorobenzene (TCB) and 1,2-dichlorobenzene (o-DCB), although the first one is the more popular in the industry.
The chlorinated solvents have a large environmental impact and the supply and disposal of this kind of solvents is turning difficult in some countries. In Europe and USA, TCB is more used while in other countries, like in Japan, o-DCB has been the solvent of choice for a long time. Reasons to move from TCB to o-DCB are here discussed: lower boiling and freezing point, higher TLV values, lower price… Laboratories using crystallization techniques (CRYSTAF, TREF, …) to sub-ambient temperatures are already required to use o-DCB, so moving the GPC instruments to o-DCB can simplify the overall laboratory solvent management tasks.
A comparison of the behavior of the two solvents as GPC mobile phase is here presented, with special emphasis on the chemical composition detection by Infrared (IR). Detector calibration for Short Chain Branching (SCB) determination, sensibility and detection limits are compared in each case. The response factors of the IR detector as concentration detector for different types of polyolefins are also determined for both solvents, as well as the detector Signal to Noise Ratio (SNR) obtained.