Determination of short‐chain branching content in polyethylene by pyrolysis comprehensive multidimensional gas chromatography using low thermal mass column technology

Abstract

A research effort was undertaken to utilize the pyrolysis process to create fragments of polyethylene that could be indicative of branching, and allow quantitiation of said short-chain branches by pyrolysis comprehensive 2-D GC (Py-GC x GC). Several strategies for sample introduction and pyrolysis such as the in-column pyrolysis device and the programmed temperature vaporizer (PTV) were studied. The chromatographic separations were executed using low-thermal mass (LTM) comprehensive 2-D GC (GC x GC). A series of polyethylene-co-hexene samples were analyzed and a linear correlation of 1-hexene content with branching peak ratio was found. Correlation coefficients were determined as 0.97 for the measurements performed.

Rapid analysis of polyester and polyethylene blends by ion mobility-mass spectrometry

“…Therefore, like PLA the classical way reported to study poly-olen involves a step of pyrolysis before MS analysis. [8][9][10][11] In particular, Lattimer described the pyrolysis residue of PE and its formation mechanisms. He reported three fragment distributions, corresponding to alkenes with an m/z of 14n (referred to as A), alkanes with an m/z of 14n + 2 (referred to as B) and dialkenes with an m/z of 14n À 2 (referred to as C).…”

Comprehensive two dimensional gas chromatography review

“…Eckerle et al [55] applied the Py process for the generation of fragments of polyethylene that could be indicative of branching, and allowed quantification of said short-chain branches by Py-GC6GC. Several strategies for sample introduction and Py, such as the in-column Py device and the programmed temperature vaporizer were reported.…”

“…3-D representation of Py-GC6GC fragment pattern of PE-cohexene. The arrow indicates tentative Me-C13 alkene, which was used for establishing correlation plots [55].…”

Characterization of Polyethylene Branching by Thermal Analysis-Photoionization Mass Spectrometry

“…Another useful technique is nuclear magnetic resonance (NMR). It can be used to determine short-chain branching (SCB) or long-chain branching (LCB), but it is limited by sensitivity (≥1/1000 branched C atoms) and by its inability to differentiate side chains with more than six carbon atoms. , …”

“…Pyrolysis gas chromatography (Py-GC) is another common polymer science technique, which is typically used to qualitatively characterize polymers or analyze additives. , Quantification of branching was also attempted, , but reliable quantitative determination of branching of polyethylene is not accessible yet. Nevertheless, the pyrolysis process offers access to structural information and circumvents nonvolatility by breaking molecules down into smaller and more volatile products.…”