Polymer Relaxation Times from Birefringence Relaxation Measurements

1967 ◽  
Vol 47 (12) ◽  
pp. 5008-5017 ◽  
Author(s):  
Douglas S. Thompson ◽  
Stanley J. Gill
Keyword(s):  
Relaxation Times ◽  
Polymer Relaxation ◽  
Relaxation Measurements ◽  
Birefringence Relaxation

Messung kernmagnetischer Relaxationszeiten in Hochauflösung mittels schneller adiabatischer Passagen

1970 ◽  
Vol 25 (11) ◽  
pp. 1674-1680
Author(s):  
Hans Lütje
Keyword(s):  
High Resolution ◽  
Polyethylene Oxide ◽  
Magnetic Relaxation ◽  
Chemical Shifts ◽  
Signal To Noise Ratio ◽  
Relaxation Times ◽  
Resonance Signal ◽  
Additional Equipment ◽  
Relaxation Measurements ◽  
Fast Passage

Abstract The nuclear magnetic relaxation times T1 and T2 may be determined by observing the relaxation that follows after a stop of an adiabatic fast passage at different points of the resonance signal. High resolution measurements are possible with external proton stabilization during the relaxation process if the chemical shifts are larger than 1 ppm and the relaxation times are longer than 1 sec. If no high resolution is required the lower limit is 0.2 seconds. Relaxation measurements are possible using conventional NMR-spectrometers without additional equipment. Since the signal to noise ratio is favourable, rather dilute solutions may be investigated. Relaxation measurements on benzene, on 4 different protons of 4-dimethylamino-benzaldehyde and on polyethylene oxide in solution are reported.

Dielectric Studies of Smectogenic Members of the 4’-alkyl-4-cyanobiphenyl (nCB) Homologous Series

2004 ◽  
Vol 59 (6) ◽  
pp. 316-324 ◽  
Author(s):  
Joanna Czub ◽  
Urszula Gubernat ◽  
Bo Gestblom ◽  
Roman Da̡browski ◽  
Stanisław Urban
Keyword(s):  
Homologous Series ◽  
High Frequency ◽  
Relaxation Times ◽  
Low Frequency ◽  
Activation Entropy ◽  
Viscosity Data ◽  
Dielectric Studies ◽  
Smectic A ◽  
Relaxation Measurements ◽  
Molecular Rotations

Results of dielectric studies of smectogenic members of the nCB (4’-alkyl-4-cyanobiphenyl, n = 9÷12) homologous series are presented. The dielectric relaxation measurements were performed in the isotropic (Is) and smectic A (SA) phases. The relaxation times characterizing the molecular rotations around the short axes (the low frequency, l. f., process) were established for both phases. In the Is phase the high frequency process connected with the molecular rotations around the long axes was also determined. The l. f. relaxation times were analysed using the Arrhenius and Bauer activation equations, which yielded the activation enthalpy ΔH and activation entropy ΔS. All results were analysed together with the literature data on the shorter members of the homologous series as well as on 14CB recently published. The ΔH and ΔS values show typical odd-even alternation that is especially well seen for the shorter members. In the Is phase the l. f. relaxation times are related to the viscosity data measured recently by Jadzyn et al.

Structure of Thermally Modified Wood Studied by Liquid State NMR Measurements

Holzforschung ◽  
2002 ◽  
Vol 56 (5) ◽  
pp. 522-528 ◽  
Author(s):  
S. Hietala ◽  
S. L. Maunu ◽  
F. Sundholm ◽  
S. Jämsä ◽  
P. Viitaniemi
Keyword(s):  
Relaxation Times ◽  
Nmr Relaxation ◽  
Spectroscopic Techniques ◽  
H Nmr ◽  
Yield Information ◽  
Cell Dimensions ◽  
Relaxation Measurements ◽  
Nmr Methods ◽  
Thermally Modified Wood ◽  
Pfg Nmr

Summary Thermal modification is a technique to produce wood with increased dimensional stability and lower equilibrium moisture content. 2H NMR relaxation measurements and pulsed field gradient (PFG-NMR) methods are non-invasive spectroscopic techniques that can be used to measure the response of liquid confined in porous materials and yield information on the size and distribution of the pores. These methods were used to study the structure and changes in structure of thermally modified Scots pine wood. The 2H longitudinal relaxation measurements of wood samples at different moisture contents showed different relaxation times and relaxation time distribution in the thermally treated samples. The effect of the thermal treatments on the cell size in wood samples was studied by PFG-NMR measurements with different dwell times. The PFG-NMR measurements showed no clear change in the cell dimensions of the thermally modified samples compared with control samples taken from the same log.

scholarly journals NMR Relaxation Measurements on Complex Samples Based on Real-Time Pure Shift Techniques

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 473
Author(s):  
Xiaoqing Lin ◽  
Haolin Zhan ◽  
Hong Li ◽  
Yuqing Huang ◽  
Zhong Chen
Keyword(s):  
Magnetic Field ◽  
Real Time ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Relaxation Method ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Transverse Spin ◽  
Complex Samples ◽  
Relaxation Measurements

Longitudinal spin-lattice relaxation (T1) and transverse spin-spin relaxation (T2) reveal valuable information for studying molecular dynamics in NMR applications. Accurate relaxation measurements from conventional 1D proton spectra are generally subject to challenges of spectral congestion caused by J coupling splittings and spectral line broadenings due to magnetic field inhomogeneity. Here, we present an NMR relaxation method based on real-time pure shift techniques to overcome these two challenges and achieve accurate measurements of T1 and T2 relaxation times from complex samples that contain crowded NMR resonances even under inhomogeneous magnetic fields. Both theoretical analyses and detailed experiments are performed to demonstrate the effectiveness and ability of the proposed method for accurate relaxation measurements on complex samples and its practicability to non-ideal magnetic field conditions.

Compressive Viscoelastic Properties of Human Dentin : I. Stress-Relaxation Behavior

1975 ◽  
Vol 54 (6) ◽  
pp. 1207-1212 ◽  
Author(s):  
Manville G. Duncanson ◽  
Edward Korostoff
Keyword(s):  
Distribution Function ◽  
Stress Relaxation ◽  
Linear Dependence ◽  
Viscoelastic Properties ◽  
Relaxation Times ◽  
Relaxation Modulus ◽  
Stress Relaxation Behavior ◽  
Relaxation Measurements ◽  
Human Dentin ◽  
Logarithmic Distribution

Stress-relaxation measurements were performed on specimens of radicular human dentin. The relaxation modulus showed a linear dependence on the logarithm of time and the approximation to the logarithmic distribution function of relaxation times was used to predict the behavior of other viscoelastic properties. This experimental technique provides significant criteria for the design of polymeric restorative and prosthetic materials.

Diffusivity and Nuclear Spin Relaxation Measurements at High Pressure in Methanol

1997 ◽  
Vol 499 ◽  
Author(s):  
R. F. Marzke ◽  
D. P. Raffaelle ◽  
G. H. Wolf ◽  
J. L. Yarger
Keyword(s):  
Spin Relaxation ◽  
Nuclear Spin ◽  
Hydrodynamic Radius ◽  
Relaxation Times ◽  
Einstein Relation ◽  
Nuclear Spin Relaxation ◽  
Simple Modification ◽  
Molecular Correlation ◽  
Relaxation Measurements ◽  
Diamond Anvil

ABSTRACTDiffusivity D and nuclear spin relaxation times T1 and T2 have been measured by NMR to 4.0 GPa in methanol, using a diamond anvil cell probe. In pure MeOH, D−1 and T2 show essentially identical activation volumes. However, these are ∼18% larger than the activation volume of viscosity. By relating these observations to an average molecular correlation time a pressure-dependent infinite-frequency shear modulus G∞ can be inferred, using two independent approaches. The relation between diffusivity and viscosity shows increasing departure from Stokes-Einstein behavior with increasing pressure, if a constant hydrodynamic radius is assumed. This departure is attributed to the pressure dependence of G∞, and can be described empirically by a simple modification of the Stokes-Einstein relation.

1H-Detected quadrupolar spin–lattice relaxation measurements under magic-angle spinning solid-state NMR

2019 ◽  
Vol 55 (39) ◽  
pp. 5643-5646 ◽  
Author(s):  
Maria Makrinich ◽  
Amir Goldbourt
Keyword(s):  
Solid State Nmr ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Proton Detection ◽  
Spin Lattice ◽  
Relaxation Measurements ◽  
Angle Spinning

Proton detection and phase-modulated pulse saturation enable the measurement of spin–lattice relaxation times of “invisible” quadrupolar nuclei with extensively large quadrupolar couplings.

Research of Calibration Curves NMR Relaxation Times of Nanoparticles Gadolinium Oxide

2014 ◽  
Vol 487 ◽  
pp. 94-97
Author(s):  
Chun Lin Yang ◽  
Mei Gui Ou ◽  
Jia Zeng ◽  
Xiu Qun Yang
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Gadolinium Oxide ◽  
Free Ions ◽  
Calibration Curves ◽  
Relaxation Measurements ◽  
Nmr Relaxation Times

In this paper, a method of assay based on NMR (Nuclear Magnetic Resonance) measurements was developed. A protocol for the dissolution of gadolinium oxide cores and calibration curves were established for Nanoparticles gadolinium oxide. After optimization this method was used for several applications such as checking the concentration in colloids after dialysis or controlling the concentration and the form (oxides or free ions) of lanthanides after in vivo injection. The Experiments showed the samples did not present any suspension or deposit after the dissolution treatment, The concentrations calculated from relaxation measurements are very close to the concentrations measured . According to measure relaxation times T1 and T2, we can approximately determinate the gadolinium concentration. .

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