Polymers
NMR water self-diffusion and relaxation studies on sodium polyacrylate solutions and gels in physiologic ionic solutions
Water self‐diffusion coefficients and longitudinal relaxation rates in sodium polyacrylate solutions and gels were measured by NMR, as a function of polymer content and structure in a physiological concentration range of monovalent and divalent cations, Ca2+ and Na+. Several physical models describing the self‐diffusion of the solvent were applied and compared. A free‐volume model was found …
Nuclear magnetic resonance profiling of chemical warfare agent simulant mass-transport through a multilayered polymeric coating
Temporary peelable coatings (TPCs) protect military equipment surfaces against chemical warfare agents (CWAs) by absorbing liquid contamination, thereby reducing the contact and vapor hazards to personnel. An understanding of the liquid CWA mass-transport mechanisms governing sorption is critical toward optimizing coating properties for reducing these hazards. We applied Nuclear Magnetic Resonance profiling to resolve mass-transport …
Estimation of Self-Diffusion Coefficients of Small Penetrants in Semicrystalline Polymers Using Single-Sided NMR
A simple and fast way to measure proton self‐diffusion coefficients of small penetrant molecules in semicrystalline polymers is introduced. The approach takes advantage of the strong static gradient of a mobile single‐sided NMR sensor and it is demonstrated on PE samples with varying degrees of crystallinity fully saturated in either toluene or n‐hexane. The self‐diffusion …
Investigation of deformation mechanisms during latex film formation by combination of unilateral NMR and near infrared measurements
Unilateral solid state NMR and near infrared measurements are combined to study latex film formation at different temperatures and humidities in order to cover a broad parameter-space of film formation conditions. From analysis of nuclear magnetic resonance (NMR) data the time evolution of water and polymer fraction at different (vertical) positions in the film were estimated. The …
Optimierung der Umhüllung von Stahlrohren
Das Verständnis der Korrosions- bzw. Alterungsvorgänge in teilkristallinen Polymeren wie beispielsweise Polyethylen oder Polypropylen und deren Einfluss auf das Bruchverhalten ist eine wesentliche Voraussetzung zur Optimierung von Umhüllungssystemen für Stahlrohre. Die in der Praxis beobachteten Effekte und Ursachen der Spannungsrissbildung werden derzeit anhand von Erkenntnissen aus Zugversuchen diskutiert. Für die Beantwortung der damit verbundenen Fragestellung, …
Aging of polyethylene: Non-destructive testing with mobile magnetic resonance
Magnetic Resonance (NMR: Nuclear Magnetic Resonance) is known in medical imaging as a diagnostic tool and in chemistry as a spectroscopic method for molecular structural analysis. In both cases, the object of interest is investigated with radio-frequency waves in the center of strong super-conducting magnets. High and homogeneous magnetic fields simplify the measurement process, but …
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Investigation of silicone breast implants with the NMR-MOUSE
Silicone breast implants are used for breast augmentation and breast reconstruction. The issues of concern associated with such implants are: (a) the quality control of each implant before implantation, and (b) the detection of implant bleeding after implantation. We have studied the use of the Nuclear Magnetic Resonance–MObile Universal Surface Explorer (NMR-MOUSE) for the nondestructive …
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NMR mobil: Wie altert Polyethylen?
Die NMR‐Mouse für die zerstörungsfreie NMR‐Analytik läuft mit einem Spektrometer von der Größe eines Notebooks. Sie untersucht Rohre und Benzintanks aus Kunststoff, Autoreifen und Schläuche, Gemälde alter Meister, lebende Haut und Mumien. Auch Tomogramme und NMR‐Spektren von Flüssigkeiten lassen sich in Auflagetechnik messen. Blümich, NMR mobil: Wie altert Polyethylen? Nachrichten aus der Chemie 55 (2007) …