Polymer crystallinity and crystallization kinetics via benchtop 1H NMR relaxometry: Revisited method, data analysis, and experiments on common polymers. (6th June 2018)

• Record Type: Journal Article
• Authors: Räntzsch, Volker; Haas, Manuel; Özen, Mürüvvet B.; Ratzsch, Karl-Friedrich; Riazi, Kamran; Kauffmann-Weiss, Sandra; Palacios, Jordana K.; Müller, Alejandro J.; Vittorias, Iakovos; Gisela Guthausen, ; Wilhelm, Manfred
• Is Part Of: Polymer. Volume 145(2018)
• Page Start: 162
• Page End: 173
• Publication Date: 2018-06-06
• Subjects: Polymer crystallinity -- Crystallization kinetics -- Semi-crystalline polymers -- Low-field NMR -- TD-NMR -- NMR relaxometry -- Molecular dynamics; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.04.066
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Semi-crystalline polymers play an enormously important role in materials science, engineering, and nature. Two thirds of all synthetic polymers have the ability to crystallize which allows for the extensive use of these materials in a variety of applications as molded parts, films, or fibers. Here, we present a study on the applicability of benchtop 1 H NMR relaxometry to obtain information on the bulk crystallinity and crystallization kinetics of the most relevant synthetic semi-crystalline polymers. In the first part, we investigated the temperature-dependent relaxation behavior and identified T = T g + 100 K as the minimum relative temperature difference with respect to T g for which the mobility contrast between crystalline and amorphous protons is sufficient for an unambiguous determination of polymer crystallinity. The obtained bulk crystallinities from 1 H NMR were compared to results from DSC and XRD, and all three methods showed relatively good agreement for all polymers. In the second part, we focused on the determination of the crystallization kinetics, i.e., monitoring of isothermal crystallization, which required a robust design of the pulse sequence, precise temperature calibration, and careful data analysis. We found the combination of a magic sandwich echo (MSE) with a short acquisition time followed by a Carr-Purcell-Meiboom-Gill (CPMG) echo train with short pulse timings to be the most suitable for monitoring crystallization. This study demonstrates the application of benchtop 1 H NMR relaxometry to investigate the bulk crystallinity and crystallization kinetics of polymers, which can lead to its optimal use as an in-situ technique in research, quality control, and processing labs. Graphical abstract: Image 1 Highlights: Study of the temperature-dependent NMR relaxation behavior of semi-crystalline polymers. Application of benchtop 1 H NMR relaxometry to investigate the bulk crystallinity and crystallization kinetics of polymers. Comparison to results from differential scanning calorimetry and X-ray diffraction.