Spatially resolved NMR in polymer science

Abstract

Selected applications of spatially resolved NMR are presented, which demonstrate the use of the method for investigating applied topics relevant to polymer and materials science. Examples are given for imaging of rigid, soft, and fluid matter. They include characterization and interpretation of electrical aging in poly(ethylene), cross-link density at the interface of covulcanized elastomer sheets, and cross-filtration in hollow-fiber filter modules. A novel NMR dectector, the NMR-MOUSE, has been developed for process and quality control by relaxation measurements. Its use for non-destructive determination of the glass-transition temperature by room temperature measurements on elastomer samples is demonstrated.

Mobile single-sided NMR

“…For small K, C 2 = n R T/2 correlates with the chemical cross-link density n. Cross-link density can also be determined via the glass temperature T g (Fig. 42a) [59,276,464,561,567] and the degree Q of swelling. The latter specifies the volume ratio of solvent-saturated and dry samples, and n scales with Q À5/3 [558].…”

“…Mobile unilateral NMR sensors are suitable for a variety of applications in materials testing [4,121,156,464], in particular of rubber [126,[464][465][466][467], and other polymer products, such as solid polymers [301,315,468]. The use of such sensors [42] had been published before in the context of inspecting solid rocket motor bond-lines nondestructively [469][470][471].…”

Cultural Heritage Studies with Mobile NMR

“…When the protective varnish layer becomes soiled, brittle,o ry ellow,i tc an be removed using solvents or more recently,l asers. [57] Both procedures are invasive and risk irreversible damage.Solvent cleaning makes the binder brittle [58] as low-molecular-weight components are leached out, similar to loss of plasticizer in polymers [59] when solvent molecules are introduced into the paint. [60] This effect was reliably observed in two paintings from 1616 by the same artist, one in its original state,the other one having been cleaned with solvents at least twice (Figure 6).…”

Determination of Velocity Autocorrelation Functions by Multiple Data Acquisition in NMR Pulsed-Field Gradient Experiments

“…For the quantification of correlations, however, it is not necessary to obtain the full two-dimensional probability density of displacements, rather can such numbers be derived from averaged moments of displacements which are accessible by similar, but much less time-consuming one-dimensional NMR experiments where all PFGs are varied simultaneously. Such methods have, for instance, been applied to distinguish between coherent and fluctuating motions in Poiseuille flow (12), flow through hollow-fiber membranes (13), and rotating granular media (14).…”