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Characterization of polyethylene branching by thermal analysis-photoionization mass spectrometry.
J. Am. Soc. Mass Spectrom. 31, 2362-2369 (2020)
DOI Verlagsversion bestellen
The rising demand for more and more specialized polyethylene represents a challenge for synthesis and analysis. The desired properties are dependent on the structure, but its elucidation is still intricate. For this purpose, we applied thermal analysis hyphenated to single photon ionization mass spectrometry (STA-SPI-MS). The melting and pyrolysis behavior of different types of polyethylene were tracked by DSC and mass loss. Crystallinity and melting point give hints about the branching but are also influenced by the molecular weight distribution. The evolving gas analysis patterns obtained by SPI-MS however, contain specific molecular information about the samples. Shifts in the summed spectra, which can be clearly observed with our technique, result from differently favored degradation reactions due to the respective structure. Pyrolysis gas chromatography mass spectrometry (Py-GC-EI-MS) was used to support the assignment of pyrolysis products. Principal component analysis was successfully applied to reduce the complexity of data and find suitable markers. The obtained grouping is based on the molecular fingerprint of the samples and is strongly influenced by short-chain branching. Short and medium alkenes and dienes have the strongest impact on the first four principal components. Thus, two marker ratios could be defined, which also give a comprehensible and robust grouping. Butene and pentene were the most abundant signals in our set of samples. With STA-PI-MS, a broad range of pyrolysis products can be measured at the same time, possibly extending the range for quantifiable short-chain branches to more than six carbon atoms for PE. Unfortunately, no clear trend between long-chain branching and any grouping was observed. The quite universal and soft single photon ionization enables access to many different compound classes and hence other polymers can be studied.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
Schlagwörter Single-photon Ionization; Enhanced Multiphoton Ionization; Electron-ionization; Molecular-weight; Pyrolysis; Chromatography; Resonance; Decomposition; Degradation; Polypropylene
Quellenangaben Band: 31, Heft: 11, Seiten: 2362-2369
Verlagsort 1155 16th St, Nw, Washington, Dc 20036 Usa
Begutachtungsstatus Peer reviewed