Quantification of identical and unique segments in ethylene-propylene copolymers using two dimensional liquid chromatography with infra-red detection

Abstract

Hyphenating high temperature high performance liquid chromatography (HT-HPLC) with high temperature size exclusion chromatography (HT-SEC) (high temperature two dimensional liquid chromatography (HTHPLC x HT-SEC or HT 2D-LC)) leads to an isocratic elution in the second dimension, which in turn enables to use IR detector (quantitative detection) for monitoring the eluting polymers. Experimental data obtained from HT 2D-LC with IR detector are usually presented as contour plots, which can be mathematically described in matrices. Quantitative data about chemical composition, molar mass and concentration of all the segments, which are present in a polymer, can be obtained, after calibrating the HPLC separation (HPLC elution volume vs chemical composition), SEC separation (SEC separation vs molar mass) and response of the IR detector (IR response vs mass of the polymer). A new procedure based on subtraction and addition of matrices is described, which enables quantitative comparison of different polymer materials. This procedure enables to determine, which components are present in both materials (i.e., identical components or segments) and which are present only in one from both the materials (i.e., unique segments). Moreover, molar mass distribution, as well as chemical composition distribution of both identical and unique segments is evaluated from experimental data. The procedure was applied on two different ethylene-propylene copolymer samples. Polyolefins J (2016) 3: 119-133