NMR Imaging Studies of Vulcanized Butyl Rubber

1991 ◽  
Vol 64 (4) ◽  
pp. 635-640 ◽  
Author(s):  
M. R. Krejsa ◽  
J. L. Koenig
Keyword(s):  
Crosslink Density ◽  
Relaxation Times ◽  
Nmr Imaging ◽  
Thermal Gradients ◽  
Chemical Probes ◽  
Imaging Studies ◽  
Spin Lattice ◽  
T1 Relaxation ◽  
Entrapped Air ◽  
Effects Of Aging

Abstract NMR imaging is a useful technique for studying the physical and spatial microstructure of cured elastomers. Different swelling agents can be used as chemical probes to detect varying amounts of microstructural differences. Imaging can be used to detect highly cured regions due to aging, poor mixing, and thermal gradients. NMRI is thus useful to study spatial distribution of crosslinks and is sensitive to changes in this distribution of crosslinks due to thermal gradients and the effects of aging and reversion processes. It can also be used to observed entrapped air in air-aged samples. Spin-lattice T1, relaxation times for solvent in cured elastomers have been shown to be shorter than the bulk solvent T1 values, providing a new method for determining the crosslink density. NMRI results have suggested that cure reversion and postcuring processes produce similar spatial results.

Characterization of Biomaterials with NMR

1990 ◽  
Vol 217 ◽  
Author(s):  
Leoncio Garrido ◽  
Bettina Pfleiderer ◽  
Jerome L. Ackerman ◽  
John Moore
Keyword(s):  
Chemical Shift ◽  
Mechanical Stress ◽  
Imaging Techniques ◽  
Relaxation Times ◽  
Nmr Imaging ◽  
Spin Lattice ◽  
Model Networks ◽  
Crosslink Densities

ABSTRACTSilicone based biomaterials are characterized with NMR. Bulk spin-lattice (T1) and spin-spin (T2) relaxation times are measured in polydimethylsiloxane (PDMS) model networks and various types of implants. The T2 results seem to indicate that crosslink densities of these biomaterials are lower than those of the PDMS model networks studied. 1H chemical shift NMR imaging techniques are developed to investigate the aging (e.g., migration of free polymer, rupture due to mechanical stress, etc.) of biomaterials in vivo.

Spin Labeled Chelating Agents and their Gadolinium Complexes as Contrast Enhancing Agents for NMR Imaging

1985 ◽  
Vol 40 (11) ◽  
pp. 1558-1562 ◽  
Author(s):  
George Sosnovsky ◽  
Shu Wen Li ◽  
N. Uma Maheswara Rao ◽  
Robert C. Brasch
Keyword(s):  
Chelating Agents ◽  
Relaxation Times ◽  
Proton Relaxation ◽  
Nmr Imaging ◽  
Relaxation Properties ◽  
Spin Lattice ◽  
Gadolinium Complexes ◽  
High Proton

Spin labeled EDTA, CDTA and DTPA chelating agents and their gadolinium complexes were synthesized and evaluated for their effects on the spin-lattice (T1) and spin-spin (T2) relaxation times of water, plasma, and blood. It was found that the spin labeled chelating agents are effective proton relaxation agents. Although, the gadolinium complexes of these agents have superior relaxation properties, the differences in relaxivitv between the spin labeled complexes and the non-spin labeled gadolinium complexes are marginal. The spin labeled agents and their gadolinium complexes are expected to be very useful in designing paramagnetic conjugates with biomolecules. In particular, the latter type possesses high proton relaxivity combined with a nitroxvl marker which can be followed pharmacokinetically by EPR.

scholarly journals Micro DSC and NMR MOUSE studies of collagen–vegetable tannin interaction mechanism during leather making

2020 ◽  
Author(s):  
Claudiu Sendrea ◽  
Maria-Cristina Micu ◽  
Emanuel Hadimbu ◽  
Simona Maria Paunescu ◽  
Iulia Maria Caniola ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Water Environment ◽  
Interaction Mechanism ◽  
High Sensitivity ◽  
Collagen Matrix ◽  
Spin Lattice ◽  
Dsc Measurements ◽  
T1 Relaxation ◽  
Micro Dsc ◽  
Portable Nmr

In this study NMR MOUSE and micro DSC techniques were used to investigate the interaction between collagen and various vegetable tannins during leather making process with the aim of gaining a deeper understanding of different water environment in relation to tannin type. We have previously showed that relaxation times may provide useful information on collagen matrix properties. The vegetable tanned leathers were obtained by patented techniques inspired from ancient recipes at the National R&D Institute for Textile and Leather, ICPI Division, Bucharest using various vegetable extracts such as myrobalan, gambier and chestnut. Longitudinal and transversal relaxation times T1 and T2eff were measured using a PM2 portable NMR-MOUSE with 20.05 MHz frequency. Micro DSC measurements were carried out with a high-sensitivity SETARAM Micro-DSC III in the temperature range (5 to 95) °C at 0.5 K min-1 heating rate. The investigated leathers showed significant differences in the values of spin-spin (T2eff) and spin-lattice (T1) relaxation times depending on tannin type that well corelates with the variation of the calorimetric parameters (denaturation temperature and enthalpy, peak shape). These results highlight the complementarity of the information obtained by the two techniques and open new ways for both designing new leather assortments and analyses of historical and archaeological leather.

scholarly journals The Water Polymorphism and the Liquid–Liquid Transition from Transport Data

Physchem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 202-214
Author(s):  
Francesco Mallamace ◽  
Domenico Mallamace ◽  
Giuseppe Mensitieri ◽  
Sow-Hsin Chen ◽  
Paola Lanzafame ◽  
...  
Keyword(s):  
Specific Heat ◽  
Relaxation Times ◽  
Configurational Entropy ◽  
Self Diffusion ◽  
Spin Lattice ◽  
Glass Forming ◽  
T1 Relaxation ◽  
Liquid Transition ◽  
Measured Water ◽  
Supercooled Region

NMR spectroscopic literature data are used, in a wide temperature-pressure range (180–350 K and 0.1–400 MPa), to study the water polymorphism and the validity of the liquid–liquid transition (LLT) hypothesis. We have considered the self-diffusion coefficient DS and the reorientational correlation time τθ (obtained from spin-lattice T1 relaxation times), measured, respectively, in bulk and emulsion liquid water from the stable to well inside the metastable supercooled region. As an effect of the hydrogen bond (HB) networking, the isobars of both these transport functions evolve with T by changing by several orders of magnitude, whereas their pressure dependence become more and more pronounced at lower temperatures. Both these transport functions were then studied according to the Adam–Gibbs model, typical of glass forming liquids, obtaining the water configurational entropy and the corresponding specific heat contribution. The comparison of the evaluated CP,conf isobars with the experimentally measured water specific heat reveals the full consistency of this analysis. In particular, the observed CP,conf maxima and its diverging behaviors clearly reveals the presence of the LLT and with a reasonable approximation the liquid–liquid critical point (LLCP) locus in the phase diagram.

scholarly journals Reproducibility of T1 relaxation times in diagnostic MRI: A phantom study

2021 ◽  
pp. 100038
Author(s):  
Derick Yongabi ◽  
Nathalie Mertens ◽  
Ronald Peeters
Keyword(s):  
Relaxation Times ◽  
Phantom Study ◽  
T1 Relaxation

scholarly journals QTC DISPERSION ON 12-LEAD ELECTROCARDIOGRAM IS INVERSELY CORRELATED WITH T1 RELAXATION TIMES IN PATIENTS WITH HYPERTROPHIC CARDIOMYOPATHY

2014 ◽  
Vol 63 (12) ◽  
pp. A1197
Author(s):  
David Hurtado de Mendoza ◽  
Celia P. Corona-Villalobos ◽  
Styliani Vakrou ◽  
Stefan L. Zimmerman ◽  
Yalda Soleimanifard ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Relaxation Times ◽  
Qtc Dispersion ◽  
T1 Relaxation
Sign in / Sign up

Export Citation Format

Share Document