Low-field RheoNMR: Newly developed combination of rheology and time domain (TD)-NMR to correlate mechanical properties with molecular dynamics in polymer melts

Räntzsch, Volker; Özen, Mürüvvet Begüm; Ratzsch, Karl‐Friedrich; Guthausen, Gisela; Wilhelm, Manfred

doi:10.1063/1.5016756

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…Compared to DSC, 1 H NMR relaxometry is better suited to the study of slow crystallizations as it does not require peak integration. Furthermore, the non destructive nature of 1 H NMR relaxometry allows for the performance of in situ experi ments in combination with applied flow or pressure to achieve better insight into how these parameters affect polymer crystalli zation [28,29]. Fig.…”

Section: Discussionmentioning

confidence: 99%

Polymer crystallinity and crystallization kinetics via benchtop 1H NMR relaxometry: Revisited method, data analysis, and experiments on common polymers

Räntzsch

Haas

Özen

et al. 2018

Polymer

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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 crystal linity 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 ¼ T g þ 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 crystal linity. 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.

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Section: Discussionmentioning

confidence: 99%

Polymer crystallinity and crystallization kinetics via benchtop 1H NMR relaxometry: Revisited method, data analysis, and experiments on common polymers

Räntzsch

Haas

Özen

et al. 2018

Polymer

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Linear and nonlinear shear studies reveal supramolecular responses in supercooled monohydroxy alcohols with faint dielectric signatures

Bierwirth

Honorio

Gainaru

et al. 2019

The Journal of Chemical Physics

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Monohydroxy alcohols (MAs) with methyl and hydroxyl side groups attached to the same carbon atom in the alkyl backbone can display very weak structural and supramolecular dielectric relaxation processes when probed in the regime of small electrical fields. This can render their separation and assignment difficult in the pure liquids. When mixing with bromoalkanes, a faint Debye-like process can be resolved dielectrically for 4-methyl-4-heptanol. To achieve a separation of structural and supramolecular processes in pure 4-methyl-4-heptanol and 3-methyl-3-heptanol, mechanical experiments are carried out in the linear-response regime as well as using medium-angle oscillatory shear amplitudes. It is demonstrated that first-order and third-order nonlinear mechanical effects allow for a clear identification of supramolecular viscoelastic modes even for alcohols in which they leave only a weak signature in the linear-response shear modulus. Additionally, the nonlinear rheological behavior of 2-ethyl-1-hexanol is studied, revealing that its linearly detected terminal mode does not coincide with that revealed beyond the linear-response regime. This finding contrasts with those for the other MAs studied in this work.

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Low-field RheoNMR: Newly developed combination of rheology and time domain (TD)-NMR to correlate mechanical properties with molecular dynamics in polymer melts

Cited by 2 publications

References 11 publications

Polymer crystallinity and crystallization kinetics via benchtop 1H NMR relaxometry: Revisited method, data analysis, and experiments on common polymers

Polymer crystallinity and crystallization kinetics via benchtop 1H NMR relaxometry: Revisited method, data analysis, and experiments on common polymers

Linear and nonlinear shear studies reveal supramolecular responses in supercooled monohydroxy alcohols with faint dielectric signatures

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