Time-domain NMR in polyolefin research

Litvinov, V. M.; Men, Yongfeng

doi:10.1016/j.polymer.2022.125205

Cited by 12 publications

(9 citation statements)

References 242 publications

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“…The values of T 2b were determined separately for the pure liquid samples. Effects of relaxation induced by molecular diffusion and magnetic field gradient in the observed T 2 are eliminated by the use of low-intensity magnetic fields and short echo-spacing separation. ,, Because of their hindered translational motion, solids possess small T 2 values, in the order of μs, and are undetectable in the tested conditions . The uncertainties in T 2 and ρ 2 were assessed based on the random and systematic uncertainties in sample preparation, the relaxation time of the bulk fluid, and the specific surface area of the polymers, see Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

Correlating Surface Chemistry to Surface Relaxivity via TD-NMR Studies of Polymer Particle Suspensions

Suekuni,

Allgeier

2023

JACS Au

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This study elucidates the impact of surface chemistry on solvent spin relaxation rates via time-domain nuclear magnetic resonance (TD-NMR). Suspensions of polymer particles of known surface chemistry were prepared in water and n-decane. Trends in solvent transverse relaxation rates demonstrated that surface polar functional groups induce stronger interactions with water with the opposite effect for n-decane. NMR surface relaxivities (ρ 2 ) calculated for the solid−fluid pairs ranged from 0.4 to 8.0 μm s −1 and 0.3 to 5.4 μm s −1 for water and n-decane, respectively. The values of ρ 2 for water displayed an inverse relationship to contact angle measurements on surfaces of similar composition, supporting the correlation of the TD-NMR output with polymer wettability. Surface composition, i.e., H/C ratios and heteroatom content, mainly contributed to the observed surface relaxivities compared to polymer % crystallinity and mean particle sizes via multiple linear regression. Ultimately, these findings emphasize the significance of surface chemistry in TD-NMR measurements and provide a quantitative foundation for future research involving TD-NMR investigations of wetted surface area and fluid-surface interactions. A comprehensive understanding of the factors influencing solvent relaxation in porous media can aid the optimization of industrial processes and the design of materials with enhanced performance.

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Section: Methodsmentioning

confidence: 99%

Correlating Surface Chemistry to Surface Relaxivity via TD-NMR Studies of Polymer Particle Suspensions

Suekuni,

Allgeier

2023

JACS Au

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“…Among them, the low-field nuclear magnetic resonance (LF-NMR) has gained broad interest due to its supreme ability to access the chain dynamics information. 25 The proton-based LF-NMR has been widely used to quantify the crystallinity, rigid-mobile component ratio, molecular dynamics, and morphology. For measurement temperature above T g , the dynamics difference between the rigid crystalline domain and mobile amorphous region provides us the opportunity to quantify their fractions.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous analytical techniques, that is, SAXS, 20 AFM, 21–23 and NMR 16,24 have been adopted to elucidate the microstructure of PVA in the presence of plasticizer. Among them, the low‐field nuclear magnetic resonance (LF‐NMR) has gained broad interest due to its supreme ability to access the chain dynamics information 25 . The proton‐based LF‐NMR has been widely used to quantify the crystallinity, rigid–mobile component ratio, molecular dynamics, and morphology.…”

Section: Introductionmentioning

confidence: 99%

Molecular mobility and morphology change of poly(vinyl alcohol) (PVA) film as induced by plasticizer glycerol

Fei

Cheng

et al. 2023

Journal of Polymer Science

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The addition of small molecular plasticizer is an efficient strategy to increase the process ability and macroscopic performance of poly(vinyl alcohol) (PVA). However, how the plasticizer influences the chain dynamics and morphology deserves further investigation. In this work, the PVA film with varying glycerol addition levels was used as the model system. The increasing glycerol addition‐level results in the depression of the melting temperature and crystallization temperature, which in line with Flory's theory. The enhanced chain dynamics in the mobile domain was accessed by low‐field NMR, whereas that in the crystalline region remains constant. The domain size as well as the morphology of the mobile phase are accessed by 1H spin‐diffusion NMR. The results indicate the increasing dimensionality of the plasticized PVA film with increasing the addition level of glycerol, where the addition level below 25 wt% leads to the dimensionality of 1D, and higher than 25 wt% results in the dimensionality of 2D. Current results elucidate the critical role of the plasticizer in modulating the dynamics heterogeneity of the plasticized polymer film, which is closely related to the macroscopic performance of the products.

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“…Figure b,c presents the double exponential fitting of the MSE-FID and CPMG curves. In the observation time scale of 10 –2 –10 2 ms, according to the difference of T 2 , it can be divided into The short relaxation time ( T r < 200 μ s) represented by the rigid component of network chains is contained in the MSE-FID curves. In the filler rubber system, the main form is the interface layer, which is tightly bound to the filler surface through either chemical bonds or strong adsorption. The intermediate-long relaxation time (1 ≤ T 2 ,slow ≤10 ms) characterized by topological constraints in locally restricted network chains, such as chemical cross-linking and filler. The long relaxation time ( T 2 ,fast ≥40 ms) corresponds to free tails or sols with nearly isotropic relaxation, which is independent of deformation. …”

mentioning

confidence: 99%

“…Figure 2b,c presents the double exponential fitting of the MSE-FID and CPMG curves. In the observation time scale of 10 −2 −10 2 ms, according to the difference of T 2 , it can be divided into 29 1 The short relaxation time (T r < 200 μs) represented by the rigid component of network chains is contained in the MSE-FID curves. In the filler rubber system, the main form is the interface layer, which is tightly bound to the filler surface through either chemical bonds or strong adsorption.…”

mentioning

confidence: 99%

Time-Resolved Extensional Rheo-NMR Spectroscopy for Investigating Polymer Nanocomposites under Deformation

Xiong

Xia

et al. 2023

Anal. Chem.

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Understanding the microstructure change of polymer nanocomposites (PNCs) under elongation deformation at the molecular level is the key to coupling structure−property relationships of PNCs. In this study, we developed our recently proposed in situ extensional rheology NMR device, Rheo-spin NMR, which can simultaneously obtain both the macroscopic stress−strain curves and the microscopic molecular information with the total sample weight of ∼6 mg. This enables us to conduct a detailed investigation of the evolution of the interfacial layer and polymer matrix in nonlinear elongational strain softening behaviors. A quantitative method is established for in situ analysis of (1) the fraction of the interfacial layer and (2) the network strand orientation distribution of the polymer matrix based on the molecular stress function model under active deformation. The results show that for the current highly filled silicone nanocomposite system, the influence of the interfacial layer fraction on mechanical property change during small amplitude deformation is quite minor, while the main role is reflected in rubber network strand reorientation. The Rheo-spin NMR device and the established analysis method are expected to facilitate the understanding of the reinforcement mechanism of PNC, which can be further applied to understand the deformation mechanism of other systems, i.e., glassy and semicrystalline polymers and the vascular tissues.

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Time-domain NMR in polyolefin research

Cited by 12 publications

References 242 publications

Correlating Surface Chemistry to Surface Relaxivity via TD-NMR Studies of Polymer Particle Suspensions

Correlating Surface Chemistry to Surface Relaxivity via TD-NMR Studies of Polymer Particle Suspensions

Molecular mobility and morphology change of poly(vinyl alcohol) (PVA) film as induced by plasticizer glycerol

Time-Resolved Extensional Rheo-NMR Spectroscopy for Investigating Polymer Nanocomposites under Deformation

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