Polymer Analysis by Compact NMR

• Polymeranalyse mittels Kompakt-NMR

Teymouri, Yadollah; Blümich, Bernhard (Thesis advisor); Herres-Pawlis, Sonja (Thesis advisor)

Aachen (2017)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2017

Abstract

Magnetic resonance is well known in the fields of chemical analysis and medical imaging, where typical instruments use superconducting magnets that generate high magnetic fields. However, the development of high-field NMR is limited by the cost and complexity of the equipment. During the last years considerable progress has been achieved with compact NMR machines employing permanent magnets, which provide sufficient sensitivity and robustness for nondestructive characterization in applications outdoors and on the factory floor. The aim of this work is to understand the polymer morphology and its chain dynamics upon conditions relevant to industry. This is followed by creating new NMR methodologies with compact low-field NMR. First, compact NMR is used to investigate the thermal aging and degradation of polyethylene in combination with standard test methods. The interaction of polyethylene with different solvents is analyzed at various swelling conditions by compact NMR to study solvent-induced crystallization in semi-crystalline polymers. Employing compact NMR spectroscopy coupled with the standard addition method, the wax content in polyethylene grades is differentiated with impressed accuracy. Furthermore, for a PET/PBT gradient polymer, the NMR crystallinity and the PET/PBT ratio are estimated in different depths using the profile NMR-MOUSE and 13C CPMAS spectroscopy. Lastly, by making use of stray-field NMR for non-destructive testing, the rubber fraction in rubber-modified asphalts is determined in both laboratory and field tests.