Proton Spin Diffusion Studies of Polymer Blends Having Modest Monomer Size. 2. Blends of Cellulose with either Poly(acrylonitrile) or Poly(4-vinylpyridine)

1994 ◽  
Vol 27 (10) ◽  
pp. 2826-2836 ◽  
Author(s):  
D. L. Vanderhart ◽  
R. St. John Manley ◽  
J. D. Barnes
Keyword(s):  
Polymer Blends ◽  
Spin Diffusion ◽  
Proton Spin ◽  
Diffusion Studies ◽  
Poly Acrylonitrile

Characterization of heterogeneous polymer blends by two-dimensional proton spin diffusion spectroscopy

1985 ◽  
Vol 18 (1) ◽  
pp. 119-122 ◽  
Author(s):  
P. Caravatti ◽  
P. Neuenschwander ◽  
R. R. Ernst
Keyword(s):  
Polymer Blends ◽  
Spin Diffusion ◽  
Proton Spin ◽  
Two Dimensional ◽  
Heterogeneous Polymer

Charcterization of polymer blends by selective proton spin-diffusion NMR measurements

1986 ◽  
Vol 19 (7) ◽  
pp. 1889-1895 ◽  
Author(s):  
P. Caravatti ◽  
P. Neuenschwander ◽  
R. R. Ernst
Keyword(s):  
Polymer Blends ◽  
Spin Diffusion ◽  
Proton Spin ◽  
Diffusion Nmr

scholarly journals Spatial relationships between polymers in Sitka spruce: Proton spin-diffusion studies

Holzforschung ◽  
2006 ◽  
Vol 60 (6) ◽  
pp. 665-673 ◽  
Author(s):  
Clemens Altaner ◽  
David C. Apperley ◽  
Michael C. Jarvis
Keyword(s):  
Spin Diffusion ◽  
Deuterium Oxide ◽  
Spatial Association ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Proton Spin ◽  
Cellulose Microfibrils ◽  
Spatial Proximity ◽  
Hydroxyl Groups ◽  
Diffusion Studies

Abstract The spatial arrangement of polymers in Sitka spruce (Picea sitchensis) was investigated by NMR proton spin-diffusion studies, supplemented by deuterium-exchange experiments monitored by FTIR spectroscopy. The FTIR spectra of earlywood sections after vapour-phase exchange with deuterium oxide showed that 43% of the hydroxyl groups were accessible to deuteration. This value is lower than predicted in the absence of aggregation of cellulose microfibrils into larger units, but greater than the predicted level of deuteration if 3.5-nm microfibrils surrounded by hemicellulose sheaths were aggregated into 4×4 arrays without space for deuterium oxide to penetrate between the microfibrils. The rate of proton spin diffusion between lignin and cellulose was consistent with the presence of microfibril arrays with approximately these dimensions and with lignin located outside them, in both earlywood and latewood. Proton spin-diffusion data for hemicelluloses were complicated by difficulties in assigning signals to glucomannans and xylans, but there was evidence for the spatial association of one group of hemicelluloses, including acetylated glucomannans, with cellulose surfaces, while another group of hemicelluloses was in spatial proximity to lignin. These data are consistent with a number of nanoscale models for the Sitka spruce cell wall, including a model in which glucomannans are associated with microfibril surfaces within the aggregate and water can penetrate partially between these surfaces, and one in which all non-cellulosic polymers and water are excluded from the interior of each microfibril aggregate.

Proton spin diffusion as a tool for characterizing polymer blends

1990 ◽  
Vol 34 (1) ◽  
pp. 125-159 ◽  
Author(s):  
D. L. VanderHart
Keyword(s):  
Polymer Blends ◽  
Spin Diffusion ◽  
Proton Spin

scholarly journals CP MAS kinetics and impedance spectroscopy studies of local disorder in low-dimensional H-bonded proton-conducting materials

2019 ◽  
Vol 59 (3) ◽  
Author(s):  
Laurynas Dagys ◽  
Sergejus Balčiūnas ◽  
Jûras Banys ◽  
Feliksas Kuliešius ◽  
Vladimir Chizhik ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Spin Diffusion ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Coupling Constant ◽  
Spin Lattice ◽  
Local Disorder

The 1H–13C cross-polarization magic angle spinning (CP MAS) kinetics was studied in poly(vinyl phosphonic acid) (pVPA), i.e. material with high degrees of freedom of proton motion along H-bonded chains. It has been shown that the CP kinetic data for the adjacent 1H–13C spin pairs can be described in the frame of the isotropic spin-diffusion approach. The rates of spin diffusion and spin-lattice relaxation as well as the parameters accounting for spin coupling and the effective size of spin clusters have been determined. The local order parameter S ≈ 0.63±0.02, determined as the ratio of the measured dipolar 1H–13C coupling constant and the calculated static dipolar coupling constant, is significantly lower than the values deduced for related sites in other polymers and in series of amino acids. This means that the local disorder of the C–H bonds in pVPA is between those for rather rigid C–H bond configurations having S = 0.8–1.0 and highly disordered –CH3 groups (S ~ 0.4). This effect can be attributed to the presence of the proton transfer path where proton motion is easy to activate. The activation energy for the proton motion Ea = 59±7 kJ/mol was determined from the impedance spectroscopy data analysing the temperature and frequency dependences of the complex dielectric permittivity of pVPA. The rates of proton spin-lattice relaxation and spin diffusion are of the same order and both run in the time scale of milliseconds.

Proton spin-diffusion in PVDF: a 1H–19F CP/MAS NMR study

1999 ◽  
Vol 1 (15) ◽  
pp. 3549-3555 ◽  
Author(s):  
Peter Holstein ◽  
Gustavo A. Monti ◽  
Robin K. Harris
Keyword(s):  
Spin Diffusion ◽  
Proton Spin ◽  
Mas Nmr ◽  
Nmr Study ◽  
Cp Mas Nmr

Characterization of Micro-Domain Structure of Solvent-Swollen Coal by Proton Spin Diffusion and Small Angle Neutron Scattering

2000 ◽  
Vol 14 (6) ◽  
pp. 1245-1251 ◽  
Author(s):  
Koyo Norinaga ◽  
Masashi Iino ◽  
George D. Cody ◽  
Pappannan Thiyagarajan
Keyword(s):  
Neutron Scattering ◽  
Domain Structure ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Spin Diffusion ◽  
Proton Spin
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