Non-destructive analysis of polymers and polymer-based materials by compact NMR

1 H NMR tests on damaged and undamaged XLPE and SiR samples

“…• A single spin-lattice 1 H relaxation time T 1 was observed in both XLPE and SiR samples in contrast to the two components found for T 2 . This behaviour is commonly encountered in solid polymers [28][29][30] and can be explained in terms of spin diffusion, resulting in energy transfer among 1 H spins on a time scale faster than spin-lattice relaxation processes, but slower compared with the T 2 processes. Moreover, no significant change was observed in the T 1 values due to electrical stress damage, except for a slight increase in the case of XLPE, and this fact could also be attributed to the effect of fast spin diffusion.…”

“…Overall, it was found that: A single spin–lattice 1 H relaxation time T 1 was observed in both XLPE and SiR samples in contrast to the two components found for T 2 . This behaviour is commonly encountered in solid polymers [28–30] and can be explained in terms of spin diffusion, resulting in energy transfer among 1 H spins on a time scale faster than spin–lattice relaxation processes, but slower compared with the T 2 processes. Moreover, no significant change was observed in the T 1 values due to electrical stress damage, except for a slight increase in the case of XLPE, and this fact could also be attributed to the effect of fast spin diffusion. Regarding 1 H T 2 measurements in the XLPE samples, two T 2 components were identified, a fast decaying Gaussian component assigned to protons in the rigid regions of the sample and a slower Lorentzian component stemming from the relaxation of protons in the amorphous regions of the polymer.…”

“…Proton NMR techniques were employed which focused on identifying morphological changes [25, 26], the results showed that only 10% natural deuterium determined by deuterium spectra and a short and long components of T 2 indicated the existence of different environmental states for the water. Research is expanding in the field of NMR applications with promising novel developments such as NMR sensors for on‐site monitoring of outdoor insulation [28] and compact low‐field NMR devices that offer the advantage of portability and on‐site measurements [29].…”

Screening Metal–Organic Frameworks for Separation of Binary Solvent Mixtures by Compact NMR Relaxometry

“…Among existing analytical technics, nuclear magnetic resonance (NMR) has strongly advanced our understanding about the MOF materials in terms of structure, dynamics of the linker, and motion and diffusion of adsorbed molecules by taking advantage of dedicated high-field NMR devices and sophisticated experimental techniques [36][37][38][39][40][41][42][43]. Yet, useful microscopic information can also be gained with the help of less expensive compact low-field NMR sensors with open and closed magnet geometries.…”

“…Yet, useful microscopic information can also be gained with the help of less expensive compact low-field NMR sensors with open and closed magnet geometries. Such sensors are well suited to interrogate the behavior of protonated materials and have been already successfully applied for a detailed characterization of various materials [36][37][38][39][40]. However, their application in the context of MOFs is still relatively scarce with existing studies focusing on the relaxation and diffusion behavior of gases and solvents in MOFs [41][42][43].…”