Surface UV aging of elastomers investigated with microscopic resolution by single-sided NMR

Goga, N. O.; Demco, Dan E.; Kolz, J.; Ferencz, Robert M.; Haber, Agnes; Casanova, Federico; Blümich, Bernhard

doi:10.1016/j.jmr.2007.10.017

Cited by 34 publications

(23 citation statements)

References 30 publications

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Section: Aging Of Polymersmentioning

confidence: 99%

“…In many cases the polymer material hardens with increasing age due to decreasing free volume and mounting rotational barriers for chemical groups resulting from these processes [15][16][17][18] unless chainscission dominates. 19 These changes in molecular mobility can be followed with remarkable sensitivity by NMR relaxation measurements 5,[19][20][21][22] and in particular nondestructively by mobile stray-field NMR. 17,23,24 In semi-crystalline polymers three morphological domains can be discriminated based on differences in the molecular mobility and traced by transverse 1 H NMR relaxation.…”

Section: Introductionmentioning

confidence: 99%

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Aging of polymeric materials by stray‐field NMR relaxometry with the NMR‐MOUSE

Blümich

2018

Concepts Magnetic Resonance

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The sensitivity of NMR relaxation to molecular motion is explored to study the aging of polymer materials and paint binder in master paintings. Polymeric materials are formulated from macromolecules with a distribution of molecular weights and low molecular weight additives. Their physical and chemical properties change with time due to exposure to temperature, mechanical stress, and solvents. These conditions lead to physical and chemical aging, which can proceed naturally over longer times or accelerated under artificial conditions in shorter times. Either procedure bears a particular signature on the molecular mobility, which can be probed nondestructively by the NMR relaxation times T1 and T2. Natural aging and accelerated temperature‐ and solvent‐induced aging are summarized for synthetic polymer materials and compared to aging of binders in the paint layers of paintings aged naturally over hundreds of years and aged artificially by solvent‐cleaning procedures during restoration or at elevated temperature during forgery.

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Section: Aging Of Polymersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aging of polymeric materials by stray‐field NMR relaxometry with the NMR‐MOUSE

Blümich

2018

Concepts Magnetic Resonance

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“…(2). Although a multi-exponential fitting can improve the quality of the fit, this fitting complicates this study which is mainly focused on the aging level of the insulators [20]. Moreover, in Fig.…”

Section: Experiments On the Silicone Rubber Insulatormentioning

confidence: 99%

Highly uniform single-sided portable NMR sensor and its application in assessing the aging level of silicone rubber insulators

Meng

Cheng

2015

JAE

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This study presents a high-performance single-sided portable nuclear magnetic resonance (NMR) sensor. The magnet array, which is composed of five identical cuboid permanent magnet blocks and two passive shimming sheets, generates a highly uniform B0 field in a 10 × 10 mm 2 lateral area. Along the two orthogonal lines in this lateral area, the measured B0 strength variation is less than 338 ppm. Vertically, the measured B0 magnitude decreases from 144.387 mT to 130.603 mT, with a constant gradient of 4.6 T/m from 0.15 mm to 3.15 mm above the magnet surface. A planar radiofrequency coil is optimized according to the signal-to-noise ratio level of the coil. A one-dimensional profiling experiment on an oil film shows that a vertical resolution of approximately 1.7 μm can be achieved. As an application, the silicone rubber insulators are measured using the NMR sensor. Results demonstrate that the silicone rubber insulators with different service times can be distinguished through the transverse relaxation time T2 of the silicone rubber insulators. Z. Xu et al. / Highly uniform single-sided portable NMR sensor and its applicationoptimization design on magnets should be considered to improve the homogeneity of the B 0 field in the lateral plane.Furthermore, the different magnets presented by several groups are reported. Chang et al. [7,8] introduced the following two single-sided magnet structures: one has a gradient of 10.2 T/m constructed by a single, disc-shaped permanent magnet, which is polarized in a radial direction; the other is a small Halbach magnet, which has a relatively constant gradient of 14.1 T/m between 0 and 2 mm at the top of the magnet. Perlo et al. [9] introduced the NMR-MOUSE, which has a constant gradient of 2.5 T/m. Juan et al.[10] reported a single-sided three-magnet array that has an extended constant magnetic field gradient. Raich and Blumler [11] presented a "sandwich" magnet based on the Halbach layout. This magnet has a gradient strength of roughly 0.3 T/m, and a uniformity of ∼700 ppm is observed for a 18 × 18 × 30 mm 3 water sample. Although uniformity is favorable, the magnet is not single-sided. Maxime Van Landeghem et al.[12] described a shimming approach to make the B 0 field uniform in the lateral section. The magnetic field strength (210 mT) varies by approximately 0.25 mT over a 10 × 10 mm 2 lateral slice, and the uniformity is about 1,200 ppm. Perlo et al.[13] presented a microscopic resolution single-sided NMR sensor, the magnetic field of which is approximately 410 mT, and the variation of the strength is less than 0.2 mT in a range of 10 × 10 mm 2 at a depth of 10 mm. The uniformity of this magnet is approximately 487 ppm, and to the best of our knowledge, this magnet has the best uniformity obtained from a single-sided NMR.In the recent two decades, silicone rubber insulators have been widely used in power transmission systems because of their low cost, low weight, high mechanical strength, and excellent hydrophobicity. However, the superior performance of silicone rubber insu...

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“…Even smaller and more portable MR systems can be seen in the field of “single‐sided” nuclear magnetic resonance (NMR) systems . These systems have been designed for use in chemical analytics, petrology, and food science and allow the sample under test to be placed in a sensitive region outside the device. Some of these devices, such as the NMR‐MOUSE, are commercially available.…”

Section: Introductionmentioning

confidence: 99%

The MR Cap: A single‐sided MRI system designed for potential point‐of‐care limited field‐of‐view brain imaging

McDaniel

Cooley

Stockmann

et al. 2019

Magnetic Resonance in Med

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Purpose:The size, cost, and siting requirements of conventional MRI systems limit their availability and preclude usage as monitoring or point-of-care devices. To address this, we developed a lightweight MRI for point-of-care brain imaging over a reduced field of view (FOV). Methods: The B 0 magnet was designed with a genetic algorithm optimizing homogeneity over a 3 × 8 × 8 cm FOV and a built-in gradient for slice selection or readout encoding. An external pair of gradient coils enables phase encoding in the other two directions and a radiofrequency (RF) coil provides excitation and detection. The system was demonstrated with high-resolution 1D "depth profiling" and 3D phantom imaging. Results: The lightweight B 0 magnet achieved a 64-mT average field over the imaging region at a materials cost of <$450 USD. The weight of the magnet, gradient, and RF coil was 8.3 kg. Depth profiles were obtained at high resolution (0.89 mm) and multislice rapid acquisition with refocused echoes (RARE) images were obtained with a resolution ~2 mm in-plane and ~6-mm slice thickness, each in an imaging time of 11 min. Conclusion: The system demonstrates the feasibility of a lightweight brain MRI system capable of 1D to 3D imaging within a reduced FOV. The proposed system is low-cost and small enough to be used in point-of-care applications. K E Y W O R D S accessible MRI, low-cost MRI, point of care, portable MRI | INTRODUCTIONMagnetic resonance imaging (MRI) has become a routine part of clinical medicine, especially for neuroimaging. However, expense, size, and siting requirements impose limitations on how conventional MRI scanners can be used within the health-care system. Installation of a whole-body MR scanner or even a head-only-type device using a conventional superconducting magnet entails a dedicated space, special infrastructure, and safety requirements, such as a 5-gauss exclusion area, high-power electrical supply, cooling system, and shielded room. These prerequisites preclude the use of MRI in many settings, such as rural or developingworld clinics that might not possess this infrastructure. F I G U R E 2 A, Illustration showing approximate desired magnet shape, ROI, and B 0 axis. B, Section of Halbach sphere magnet that approximates the desired magnet shape and B 0 direction. C, Discretized Halbach sphere section that approximates the continuous magnet design as an assembly of magnet blocks. D, Optimized discrete block magnet design. ROI, region of interest

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Surface UV aging of elastomers investigated with microscopic resolution by single-sided NMR

Cited by 34 publications

References 30 publications

Aging of polymeric materials by stray‐field NMR relaxometry with the NMR‐MOUSE

Aging of polymeric materials by stray‐field NMR relaxometry with the NMR‐MOUSE

Highly uniform single-sided portable NMR sensor and its application in assessing the aging level of silicone rubber insulators

The MR Cap: A single‐sided MRI system designed for potential point‐of‐care limited field‐of‐view brain imaging

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