Development of Comprehensive Two-Dimensional High Temperature Liquid Chromatography × Gel Permeation Chromatography for Characterization of Polyolefins.

Abstract

This work documents the development of the title system wherein the first dimension is a separation of polyolefins, according to composition, via an adsorption mechanism on a HYPERCARB stationary phase, and the second dimension is a separation of polyolefins on a gel permeation chromatography (GPC) column. Proper optimization of the experimental parameters including high temperature liquid chromatography (HTLC) flow rate, GPC flow rate, GPC column type, and solvent gradient program enabled successful operation of the two-dimensional (2D) system. Two angle light scattering at 90°and 15°and solution infrared absorbance detectors were used for qualitative and quantitative analysis of the 2D data. Apparent composition distribution, apparent molecular weight distribution, and the complete twodimensional (composition  molecular weight) distribution were obtained for a given polymer. This system is an improvement over a prior two-dimensional system based on temperature rising elution fractionation (TREF)/GPC in that TREF has difficulty separating polyolefins by composition if the polyolefins contain more than approximately 8 mol percent comonomer. Polyolefins synthesized from different catalysts (Metallocene and Ziegler-Natta) showed differences in the molecular weight, composition and number of resolved species in their respective 2D HTLC-GPC chromatograms as a function of catalyst type. Although the polymers studied here were all polyolefins, this approach can also be extended to other polymers.

Separation of polyolefins based on comonomer content using high‐temperature gradient adsorption liquid chromatography with a graphitic carbon column

“…Notably, this technique has also been leveraged to a 2D HT-LC/SEC technique by some of the same authors of this report. 21 To highlight this new advance, results using the silica column system designed by Heinz et al are compared against new data generated using the graphitic carbon column. 18 Previous results with a graphitic carbon column from Macko et al are also compared to the current work.…”

Recent Advances in High-Temperature Fractionation of Polyolefins

“…The first results on 2D-LC for polyolefins were published by Ginsburg et al [167,177] and Roy et al [178]. Roy et al [178] applied a separation system that was previously described by Macko et al [158,159,162].…”

“…Roy et al [178] applied a separation system that was previously described by Macko et al [158,159,162]. This system was applied to the separation of ethylene/1-octene copolymers regarding chemical composition and molar mass.…”

A review on the development of liquid chromatography systems for polyolefins

“…Realization of 2-D LC for polyolefins was announced as late as in 2010 by groups working in Freeport [104] and in Darmstadt [105]. Roy et al [104] applied the same separation system, as described by Macko et al [77,79,83] to characterize ethylene/1-octene copolymers, whereas Ginzburg et al [105] realized HPLC Â SEC on-line to separate blends of PP stereoisomers, ethylene/propylene rubbers, ethylene/norbornene copolymers and ethylene/1-hexene copolymers with homopolymers, all at 1601C, using Hypercarb/1-decanol-TCB. The 2-D (composition versus molecular weight) distributions were obtained for the blends of polymers.…”