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藤本, 亘; 福代, 新治

doi:10.2336/nishinihonhifu.43.21

Cited by 2 publications

(2 citation statements)

References 8 publications

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“…12), whereas the pulsed NMR is commonly useful only when the fraction exceeds 5 or 10 wt % in the system. 24 Ice is known to take various structures depending on the crystallization conditions. Although some of the present dielectric results can be explained by assuming the ice I structure in highly moistened wood samples, there is no definite evidence concerning the structure of the water frozen in wood.…”

Section: Third Peaksupporting

confidence: 69%

The effect of moisture on the dielectric relaxations in wood

Handa

Fukuoka

Yoshizawa

et al. 1982

J of Applied Polymer Sci

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SynopsisThe dielectric constant e' and the loss factor t" of moistened wood were measured over a wide range of moisture content (MC), 0-40 wt %, in the temperature range -196 to OOC, and in the frequency range 30 Hz to 1 M Hz. Three relaxations were observed depending on the MC and frequency. The first t" peak at -103°C (30 Hz) in oven-dried wood is known to be due to the methylol rotation in the amorphous regions. A new t" peak (second peak), which appeared for MC >0.6 wt % at -110 to -4OOC (30 Hz) depending on the MC, is assigned to the local mode motions of the complexes between moisture and polar groups in the wood system; it is enhanced as the overall loosening of the initial hydrogen bond network is promoted by the extended hydration due to further sorption of moisture. The peak temperatures and the activation energies for these relaxations changed complexly depending on the MC. At MC > 10 wt %, a novel e" peak (third peak) was disclosed around -4OOC (30 Hz) as a shoulder of the ionic conduction. This novel peak may be attributed to the water frozen in wood on the basis of the peak temperature, relaxation strength vs. MC, the activation energy, and the fact that the peak is not observed for the sorption of various polar organic solvents. This suggests that some of the moisture sorbed by wood may probably exist in a frozen state at low temperatures, even at a MC well below the commonly accepted fiber saturation point.

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Section: Third Peaksupporting

confidence: 69%

The effect of moisture on the dielectric relaxations in wood

Handa

Fukuoka

Yoshizawa

et al. 1982

J of Applied Polymer Sci

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“…This model has been used to interpret T2 relaxation data from bulk PE, PVFZ and oriented PCTFE with reasonable success. Examination of Fujimoto's data (15) though not achieved in the model the tendency is in that direction. The observed maximum in the curves for orientations y1 = 0 or 90" occurs because the corresponding elements on the fold have a sizable number of internuclear vectors inclined to the magnetic field at the magic angle, c0s-l 1/V3.…”

Section: ! Imentioning

confidence: 84%

Interfacial effects on the NMR of composite polymers

Douglass¹,

McBrierty

1979

Polymer Engineering & Sci

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Several NMR experiments can provide estimates of the scale of spatial inhomogeneity in solid materials in the range of nanometers to microns. The effects underlying these experiments their interpretation, and models used in their interpretation are discussed and illustrated with applications to polymers. Examples chosen from the literature include semicrystalline polymers (polyethylene, polyvinylidene fluoride, polychlorotrifluoroethylene), filled elastomers (carbon‐filled butadiene), copolymers (styrene: butadiene, dimethylsiloxane: bisphenol‐A polycarbonate, polyurethane) and blends (polymethylmethacrylate‐polystyreneacrylonitrile, polyvinylidene fluoride‐polymethylmethacrylate). Comparison of examples directs attention to the similarity in anisotropic motional behavior of highly constrained interfacial material in semicrystalline and filled polymers. While no one experiment is applicable to all dimensions, or all systems, NMR has proven especially useful for dimensions in the range of tens of nanometers, where other techniques are often less revealing.

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Cited by 2 publications

References 8 publications

The effect of moisture on the dielectric relaxations in wood

The effect of moisture on the dielectric relaxations in wood

Interfacial effects on the NMR of composite polymers

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