Proton Spin-lattice Relaxation Research Articles

(1)H NMR Relaxation Study of a Magnetic Ionic Liquid as a Potential Contrast Agent.

A proton nuclear magnetic relaxation dispersion (1)H NMRD study of the molecular dynamics in mixtures of magnetic ionic liquid [P66614][FeCl4] with [P66614][Cl] ionic liquid and mixtures of [P66614][FeCl4] with dimethyl sulfoxide (DMSO) is presented. The proton spin-lattice relaxation rate, R1, was measured in the frequency range of 8 kHz-300 MHz. The viscosity of the binary mixtures was measured as a function of an applied magnetic field, B, in the range of 0-2 T. In the case of DMSO/[P66614][FeCl4] the viscosity was found to be independent from the magnetic field, while in the case of the [P66614][Cl]/[P66614][FeCl4] system viscosity decreased with the increase of the magnetic field strength. The spin-lattice relaxation results were analyzed for all systems taking into account the relaxation mechanisms associated with the molecular motions with correlation times in a range between 10(-11) and 10(-7)s, usually observed by NMRD, and the paramagnetic relaxation contributions associated with the presence of the magnetic ions in the systems. In the case of the DMSO/[P66614][FeCl4] system the R1 dispersion shows the relaxation enhancement due to the presence of the magnetic ions, similar to that reported for contrast agents. For the [P66614][Cl]/[P66614][FeCl4] system, the R1 dispersion presents a much larger paramagnetic relaxation contribution, in comparison with that observed for the DMSO/[P66614][FeCl4] mixtures but different from that reported for other magnetic ionic liquid system. In the [P66614][Cl]/[P66614][FeCl4] system the relaxation enhancement associated with the paramagnetic ions is clearly not proportional to the concentration of magnetic ions, in contrast with what is observed for the DMSO/[P66614][FeCl4] system.

Oxygen Mapping within Healthy and Acutely Infarcted Brain Tissue in Humans Using the NMR Relaxation of Lipids: A Proof-Of-Concept Translational Study.

The clinical applicability of brain oxygenation mapping using the MOBILE (Mapping of Oxygen By Imaging Lipids relaxation Enhancement) magnetic resonance (MR) technique was assessed in the clinical setting of normal brain and of acute cerebral ischemia as a founding proof-of-concept translational study. Changes in the oxygenation level within healthy brain tissue can be detected by analyzing the spin-lattice proton relaxation (‘Global T 1 ’ combining water and lipid protons) because of the paramagnetic properties of molecular oxygen. It was hypothesized that selective measurement of the relaxation of the lipid protons (‘Lipids T 1 ’) would result in enhanced sensitivity of pO2 mapping because of higher solubility of oxygen in lipids than in water, and this was demonstrated in pre-clinical models using the MOBILE technique. In the present study, 12 healthy volunteers and eight patients with acute (48–72 hours) brain infarction were examined with the same clinical 3T MR system. Both Lipids R1 (R1 = 1/T1) and Global R1 were significantly different in the infarcted area and the contralateral unaffected brain tissue, with a higher statistical significance for Lipids R1 (median difference: 0.408 s-1; p<0.0001) than for Global R1 (median difference: 0.154 s-1; p = 0.027). Both Lipids R1 and Global R1 values in the unaffected contralateral brain tissue of stroke patients were not significantly different from the R1 values calculated in the brain tissue of healthy volunteers. The main limitations of the present prototypic version of the MOBILE sequence are the long acquisition time (4 min), hampering robustness of data in uncooperative patients, and a 2 mm slice thickness precluding accurate measurements in small infarcts because of partial volume averaging effects.

NMR relaxometry evaluation of nanostructured starch-PLA blends

Blends formed by starch and poly(lactic acid) (PLA) are very promising from environmental and economic standpoints, because starch is an abundant and cheap natural polymer and PLA is a biodegradable polymer that has good mechanical properties. In this study, starch-PLA blends were prepared by solution casting, employing chloroform and distilled water as a solvent pair. Then, dispersions containing 1, 3 and 5% montmorillonite clay and a dispersion containing 0.1% silica were added to the starch-PLA blends. The new materials obtained were characterized by X-ray diffraction, thermal analysis and, especially, nuclear low-field nuclear magnetic resonance (LF-NMR) relaxometry to measure the proton spin-lattice relaxation. All blends composed of starch and PLA showed significant increase in relaxation time due to the homogenous mixing of both polymers as a consequence of strong intermolecular interaction between them. Addition of clays caused substantial modification of the material and a large unique domain was observed. As a consequence, the domains corresponding to pure polymers were not observed. With the addition of the clay NT25, intermediate degradation temperatures were observed at concentrations of 3 and 5%, compared to the degradation temperatures of pure polymers. The X-ray diffraction results indicated the formation of an intercalated nanocomposite. There was an increase in the organization of the material compared to previous results observed for polymeric material, indicating the formation of an intercalated structure.

Silica and silica organically modified nanoparticles: Water dynamics in complex systems

Four silica-based porous nanosystems were synthesized with different organic substitutes and the molecular dynamics of water in these constrained environment was investigated. The nanosystems were silica and three organic modified silica nanoparticles (NP) with diameters in the range 80–300 nm with different porous dimensions, surface areas, and surface properties (e.g. hydrophilicity/hydrophobicity). Molecular dynamics was studied by pulsed field gradient NMR and by proton spin-lattice relaxation in a broad range of Larmor frequencies. A coherent analysis of the diffusion coefficients and spin-lattice relaxation data is presented taking into account a relaxation model associated to water molecular dynamics in close contact with NP surfaces. From our results it was possible to access the details of the water molecular movements in the nanosystems and to single out two water populations presenting distinct molecular dynamics. Characteristic distances for water rotations mediated by translational diffusion were estimated in consistency with the NP's dimensions and pores sizes obtained by TEM and BET experimental techniques. This knowledge has both fundamental and practical relevance since these NP have applications in nanomedicine, not only in therapy but also in diagnostic procedures and more recently in theranostic.

High-Resolution Solid-State NMR Characterization of Morphology in Annealed Polylactic Acid

Single-pulse 13C NMR spectra and spin-lattice relaxation times T1(1H), detected indirectly via 13C carbons, and T1(13C) were measured at 31°C for virgin pelletized and annealed polylactic acid (PLA) samples using the magic-angle spinning technique. The structural relaxation resulting in more regular crystals with narrower conformation distribution and increase in the lamellae thickness and crystallinity brought about by annealing at 100°C was deduced from the narrowing of the 13C NMR lines and proton spin-lattice relaxation times T1(1H). The spin-lattice relaxation times T1(13C) related to the respective carbons of the α-polymorph of PLA are also discussed in the study.

Dynamic nuclear polarization properties of nitroxyl radical in high viscous liquid using Overhauser-enhanced Magnetic Resonance Imaging (OMRI)

The dynamic nuclear polarization (DNP) studies were carried out for 15N labeled carbamoyl-PROXYL in pure water and pure water/glycerol mixtures of different viscosities (1.8cP, 7cP and 14cP). The dependence of DNP parameters was demonstrated over a range of agent concentration, viscosities, RF power levels and ESR irradiation time. DNP spectra were also recorded for 2mM concentration of 15N labeled carbamoyl-PROXYL in pure water and pure water/glycerol mixtures of different viscosities. The DNP factors were measured as a function of ESR irradiation time, which increases linearly up to 2mM agent concentration in pure water and pure water/glycerol mixtures of different viscosities. The DNP factor started declining in the higher concentration region (∼3mM), which is due to the ESR line width broadening. The water proton spin–lattice relaxation time was measured at very low Zeeman field (14.529mT). The increased DNP factor (35%) was observed for solvent 2 (η=1.8cP) compared with solvent 1 (η=1cP). The increase in the DNP factor was brought about by the shortening of water proton spin–lattice relaxation time of solvent 2. The decreased DNP factors (30% and 53%) were observed for solvent 3 (η=7cP) and solvent 4 (η=14cP) compared with solvent 2, which is mainly due to the low value of coupling parameter in high viscous liquid samples. The longitudinal relaxivity, leakage factor and coupling parameter were estimated. The coupling parameter values reveal that the dipolar interaction as the major mechanism. The longitudinal relaxivity increases with the increasing viscosity of pure water/glycerol mixtures. The leakage factor showed an asymptotic increase with the increasing agent concentration. It is envisaged that the results reported here may provide guidelines for the design of new viscosity prone nitroxyl radicals, suited to the biological applications of DNP.

Conformational stability and thermal pathways of relaxation in triclosan (antibacterial/excipient/contaminant) in solid-state: combined spectroscopic ((1)H NMR) and computational (periodic DFT) study.

The mechanism of molecular dynamics in the antibacterial/antifungal agent, triclosan (5-chloro-2-(2',4'-dichlorophenoxy)-phenol), in solid state was studied by (1)H NMR spectroscopy and periodic density functional theory (DFT) calculations. Temperature dependencies of the proton spin-lattice relaxation time (T1) in the ranges 86-293 and 90-250 K (at 15 and 24.667 MHz, respectively) and the second moment (M2) of the (1)H NMR resonant line in the range 103-300 K were measured. Two minima in the temperature dependence of T1 revealed a classical Arrhenius governed activation processes. The low temperature shallow minimum T1(T) of 71 s at 115 K, 15 MHz, which shifts with frequency, was assigned to classical hindered jumps of hydroxyl group around OC axis and with respect to a 5-chloro-2-phenol ring. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points is 9.68 kJ/mol. The pointed high temperature minimum T1(T) of 59 s at 190 K, 15 MHz, which also shifts with frequency, was assigned to the small angle librations by Θlib= ± 9° between two positions of equilibrium differing in energy by 7.42 kJ/mol. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points is 31.1 kJ/mol. Both motions result in a negligible reduction in the (1)H NMR line second moment, thus the second moment delivers an irrelevant description of the molecular motions in triclosan.

Hydrogen Dynamics in Partially Quasicrystalline Zr69.5Cu12Ni11Al7.5: A Fast Field-Cycling Relaxometric Study

We studied hydrogen dynamics in a partially quasicrystalline hydrogen storage alloy Zr69.5Cu12Ni11Al7.5 by a combination of fast field-cycling nuclear magnetic relaxometry and diffusometry in static fringe field. We demonstrate that proton spin–lattice relaxation cannot be explained using a single activation energy for proton hopping between the interstitial sites. Instead, the behavior is better explained using a Gaussian distribution of activation energies, with the average value closely matching the one obtained in independent direct diffusion measurements. Knowing the diffusion constant and the correlation times for proton jumps, we estimate the average jump length.

The Effect of Montmorillonite Clay on the Crystallinity of Poly(vinyl alcohol) Nanocomposites Obtained by Solution Intercalation and In Situ Polymerization.

In this study, PVAL/sodic clay nanocomposite materials were obtained using different clay ratios. The nanocomposites were prepared by solution and in situ polymerization. They were characterized through proton relaxometry and X-ray diffraction, the latter technique used to determine the crystallinity of the PVAL matrix in the nanocomposites through the addition of unmodified montmorillonite clay. The relaxation data for the nanocomposite films obtained by solution intercalation showed a decrease in the proton spin-lattice relaxation values with increased clay proportion, forming a nanostructured material with high exfoliation degree, as a result of two phenomena: the higher molecular mobility of the polymer chains around the clay layers and the presence of paramagnetic metals in the clay layers, which accelerates the hydrogen relaxation process, causing a decrease in the relaxation value. The samples obtained through in situ polymerization were mixed nanocomposites (partly exfoliated and partly intercalated). The NMR relaxation data for the systems analyzed showed the solution intercalation process was more efficient than in situ polymerization in relation to the generation of nanostructured polymers with higher degree of exfoliated clay.

A quantum mechanical alternative to the Arrhenius equation in the interpretation of proton spin-lattice relaxation data for the methyl groups in solids.

The theory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups have recently been given a consistent quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate (i.e., coherence-damping) processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in the condensed phase can retain quantum character over much broader temperature range than is commonly thought.

Advanced new relaxation filter-selective signal excitation methods for (13)C solid-state nuclear magnetic resonance.

We have developed new relaxation filter-selective signal excitation (RFS) methods for (13)C solid-state NMR, which enable extraction of the spectrum of a target component from a mixture of several components. These methods are based on the equalization of proton relaxation time in a single domain via rapid intraproton spin diffusion and the difference in proton relaxation time of individual components in the mixture. We recently reported two types of RFS methods using proton spin-lattice relaxation time in the rotating frame ((1)H T1rho) in (13)C solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, to increase the availability of RFS methods, we focus on proton spin-lattice relaxation time ((1)H T1). Introduction of simple pulse sequences to one-dimensional experiments reduced data acquisition time and increased flexibility, and led to the development of two new types of RFS methods using (1)H T1. We then demonstrated these methods by selectively exciting the (13)C signals of target components in a commercially available drug and a number of physical mixtures, and we showed them to be applicable to the quantitative analysis of individual components in these solid mixtures with an experimental duration of 1.5 to about 10 h. The practicality and versatility of these four RFS methods were increased by combining two or more of them, or by using a flip-back pulse, which is an effective means of shortening experimental duration. These RFS methods are suitable for use in a broad range of fields.

Proton relaxation and hydrogen mobility in Ti–V–Cr alloys: Improved exchange model

Here we propose an improved exchange model of proton relaxation to describe hydrogen mobility in intermetallic hydrides. The model has been successfully applied to a number of hydrides of ternary Ti–V–Cr alloys of different composition, namely, TiV0.8Cr1.2, Ti0.5V1.9Cr0.6 and Ti0.5V1.9Cr0.6 + 4 wt.% Zr7Ni10. It has been found that (i) there are two non-equivalent states of hydrogen (with different mobility) and (ii) there is an exchange between these two states. By analyzing proton relaxation and Knight shift data it was possible to estimate the exchange time between these states: 0.02 ms << τex << 10 ms. It means that in studied intermetallic hydrides for the proton spin–lattice relaxation one deals with the fast exchange between these states, whereas for the spin–spin relaxation the intermediate exchange is realized.

Proton and deuterium nuclear spin relaxation study of the SmA and SmC* phases of BP8Cl-d17 : a self-consistent analysis.

A self-consistent analysis of proton and deuterium nuclear spin relaxation times in the smectic phases of a partially deuterated smectogen is presented here. Proton spin-lattice relaxation times T(1Z) were measured as a function of Larmor frequency over a range of 1 kHz to 300 MHz at selected temperatures. Deuterium spin relaxation times T(1Z) and T(1Q) were measured as a function of temperature at two different magnetic fields in the smectic A phase. The deuterium data provide dynamic parameters such as rotational diffusion constants and internal jump rates as well as the nematic order parameter S. The proton data are analyzed using a number of relaxation mechanisms, one of which is the molecular reorientation. It is found helpful in these latter analyses to use the nematic order parameter and to fix the contribution from molecular reorientations determined by the deuterium spin relaxation. The fits to the proton T(1) frequency and temperature dispersions by the remaining relaxation mechanisms such as layer undulations and translational self-diffusion will be discussed for the smectic A and chiral smectic C phases.

Nuclear Magnetic Resonance Study of Atomic Motion in the Mixed Borohydride–Amide Na2(BH4)(NH2)

To study the reorientational motion of the anions and the translational diffusion of Na+ cations in the mixed borohydride–amide Na2(BH4)(NH2) showing fast-ion conduction, we have measured the 1H, 11B, and 23Na NMR spectra and spin–lattice relaxation rates in this compound over broad ranges of temperature (6–480 K) and the resonance frequency (14–132.3 MHz). At low temperatures (T < 190 K), the proton spin–lattice relaxation rate is governed by fast reorientations of BH4 groups. This reorientational process can be satisfactorily described in terms of a Gaussian distribution of the activation energies with the average Ea value of 74 ± 7 meV. Above 250 K, the measured proton spin–lattice relaxation rate originates from two other (slower) reorientational jump processes characterized by the average activation energies of 340 ± 9 meV and 559 ± 7 meV. The 23Na spin–lattice relaxation data in the high-temperature region are governed by translational diffusion of Na+ ions, which is consistent with high Na-ion cond...

SU‐E‐T‐18: A New Approach To Cancer Treatment

Purpose:To assess the correlation between mean lethal radiation doses (Do) with NMR water proton spin lattice relaxation time (T1) in different phases of Hela cells.Methods:Analysis of T1 with Do was assessed in M, G1, G2 and S‐phase at energies of 220 kVp, 280 kVp and 1.25 MeV (Co‐60).Results:T1 against Do in M, G1, G2, and S phase at 220 kVp yield a correlation of 0.80. At 280 kVp and 1.25 MeV the correlation is 0.77 and 0.82 respectively.Conclusion:It appears that T1 value decreases from M phase (1020 ± 84 ms) to S phase (534 ± 43 ms). The Do values increases from M phase to S phase. The variation in T1 and Do in different phases of the cell cycles provide a clue to time the mitotic phase at the radiation treatment time. It appears that T1 value decreases from M phase (1020 ± 84 ms) to S phase (534 ± 43 ms). The Do values increases from M phase to S phase. The variation in T1 and Do in different phases of the cell cycles provide a clue to time the mitotic phase at the radiation treatment time.

¹H-²H cross-relaxation study in a partially deuterated nematic liquid crystal.

A detailed study of the cross-relaxation effects between the ¹H and ²H spins systems is presented in the nematic phase of a 5-cyanobiphenyl (5CB) liquid crystal, partially deuterated at α position (5CB-αd₂). The proton spin-lattice relaxation time was measured at a frequency range from 5 kHz to 100 MHz at a temperature 5 K below the nematic-isotropic phase transition. In the low frequency domain, the spin-lattice relaxation rate (T₁⁻¹) dispersion clearly differs from that of the fully protonated 5CB homologue. At two distinct frequencies, T₁⁻¹ presents two distinct local maxima and for low frequencies T₁⁻¹ presents a stronger frequency dependence when compared with what is observed for 5CB. The T₁⁻¹ dispersion obtained for 5CB-αd₂ for frequencies above 60 kHz was interpreted in terms of the relaxation mechanisms usually accepted to interpret the spin-lattice relaxation in nematic phases in general and 5CB in particular. For lower frequencies it was necessary to consider cross-relaxation contributions between the proton and deuterium reservoirs. A detailed model interpretation of the deuterium quadrupolar dips with respect to the proton-spin relaxation is presented. The analysis of the quadrupolar relaxation independently confirms that the order director fluctuations is the dominant mechanism of proton relaxation in the low frequency domain.

Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin–lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA=Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

Complex Mechanism of Relaxation in Solid Chloroxylenol (Antibacterial/Antifungal Agent) Studied by 1H NMR Spectroscopy and Density Functional Theory Calculations

Molecular relaxation in antibacterial/antifungal agent: chloroxylenol (4-chloro-3,5-dimethylphenol, PCMX) in the solid state was studied by the (1)H NMR and quantum chemistry calculations. The temperature dependencies of the proton spin-lattice relaxation time (T1) in the ranges 15-273 K (at 24.667 MHz), 77-295 K (at 15 MHz), and 112-291 K at 90 MHz and the second moment (M2) of (1)H NMR resonant line in the range 106-380 K were measured. The two minima in the temperature dependence of T1 revealed two activation processes, whereas the M2 dependence in the studied range was quite flat and revealed the only significant reduction at 380 K. The low temperature part of T1(T) dependence indicated the occurrence of two processes characteristic of methyl bearing solids; the quantum mechanics governed incoherent tunneling (responsible for the low temperature flattening of T1) and the classical Arrhenius dependence governed hindered rotation (related to the wide low temperature minimum of 0.066 s at 57 K, 24.667 MHz). The 2D potential energy surface obtained using DFT/B3LYP/6-311++G(2d,p) calculations revealed the inequivalence of methyl groups and the lack of their interplay/coupling. The activation energies of classical hindered rotation are 3.35 and 2.5 kJ/mol, whereas temperatures at which the proton tunneling T(tun) finally ceases are 52 and 63 K, for inequivalent methyl groups. C(p)(T) required for the estimation of T(tun) was calculated purely theoretically on the basis of the Einstein and Debye models of specific heat and 51 modes of atomic vibrations, 4 internal rotations, and 3 torsions calculated by DFT. The -CH3 motion (tunneling and classical) results in the reduction in the (1)H NMR line second moment from 17.3 G(2) (rigid) to approximately 11.05 G(2). The pointed high temperature minimum T1(T) of 0.109 s at 89 K, 24.667 MHz, which shifts with frequency, was assigned to small-angle libration jumps, by the Θ2 = ±15° between two positions of equilibrium. The activation energy of this motion estimated on the basis of the fit of the theoretical model to the experimental points is 10.5 kJ/mol. The reduction in the (1)H NMR line second moment assigned to this motion is much lower (due to order parameter s = 0.64) and equal to 1.6 G(2). The high temperature reduction from 9.6 G(2) to 0.9 G(2) at 380 K is a result of the phase transition connected with melting (385-389 K).

Investigation on Relationship Between Energy Storage and Special Performance of L-arginine Phosphate Monohydrate (LAP) Crystal

Phosphate arginine (PA) has been known as the medium carriers for bioenergy storage, while the similar structural substance L-arginine phosphate monohydrate (LAP) crystal is an excellent nonlinear optical crystal with a high laser-induced damage threshold. Energy storage in organism and laser-induced damage in crystals are both correlative to energy. Temperature dependence X-ray diffraction (XRD) and solid state NMR spectroscopy were performed to explore the impact of energy (heat and magnetic) fields on LAP crystal. XRD results reveal that LAP processes a reversible specific phase transition as the temperature changed. Saturation recovery experiments have shown that the crystal has a long proton spin-lattice relaxation time (1H T1) of 184 s with an amazing solid-state stability. The nuclear magnetic resonance (NMR) and fluorescence emission spectra of LAP solution compared with several amino salt solutions have also been investigated. The results show that the emission wavelength of LAP solution is blue-shifted from 415 to 380 nm. When energy (laser, heat, magnetic and etc.) fields are applied on LAP crystal, it processes a various of distinctive properties which make LAP a special material worthy of further detailed investigation.

Characterisation of crumb rubber modifier using solid-state nuclear magnetic resonance spectroscopy

Crumb rubber (CR) can be used for binder modification or aggregate replacement in asphalt mixtures for road construction, when it is usually referred to as CR modifier (CRM). CRM elastic properties depend on the quality of parent material and storage conditions of final material. They deteriorate in time due to degradation processes and among other things they can influence CRM swelling capacity during asphalt rubber preparation. The presented paper demonstrates the sensitivity of basic nuclear magnetic resonance (NMR) parameters (proton spin-lattice relaxation time T1, proton spin–spin relaxation time T2 and the line broadening in 13C NMR and 1H NMR spectra) for detecting changes in CRM degradation. These NMR parameters are proposed to be used to assess CRM degradation before application in asphalt mixtures. In laboratory conditions, CRMs with different degrees of degradation were prepared by thermal ageing at 85°C for 0–36 days.