Presented at the 8th International Conference on Polyolefin Characterization (ICPC), 2023, Valencia, Spain.
By Esther López, Alberto Ortín, Benjamín Monrabal. Polymer Char, Valencia, Spain.
Infrared absorption (IR) is well stablished as concentration and chemical composition detector (methyl groups of short chain branches) in high temperature gel permeation chromatography (HT-GPC) to obtain the molar mass distribution and short chain branching of polyolefins [1- 2]. Recently, a high-performance filter-based IR detector with broad spectral range has been developed which can detect the typical C=O absorption in the 1740 cm-1 band with high sensitivity and simultaneously to the measurement of concentration and methyl groups. Thus, new applications for HT-GPC-IR become now accessible.
The present work is focused on assessing the response of the carbonyl band detection by analyzing the fourth largest produced polymer and the largest produced polyester, polyethylene terephthalate (PET), a polymer with different carbonyl groups from the well-known of ethylene vinyl acetate resins. The study checks the solubility in a specific combination of solvents mixture to obtain response in the band of 1740 cm-1 and proposes the use of the IR absorption chromatogram in that band to quantify the molar mass distribution (MMD).
Similar analysis of PET and PE blends is also presented. The purpose is to characterize the weight fraction and the molecular weight of the two components in the blends. This method will be of application, for instance to the analysis of different materials present in a multilayer film, using the same analytical method. The specific bands of absorption of PE and PET in the IR make possible the discrimination of the two components even if coeluting in the GPC analysis