A study of solvent exchange process in (ethylene–vinyl alcohol) copolymer gels by a proton nuclear magnetic resonance spectroscopy imaging method

Kanekiyo, Masahito; Kobayashi, Masatoshi; Ando, Isao; Kurosu, Hiromichi; Amiya, Shigetoshi

doi:10.1002/app.11010

Cited by 2 publications

(1 citation statement)

References 81 publications

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“…For this reason, MRI has been successfully applied to polymer gel systems. [15][16][17][18][19][20] The contrast of the resulting images is produced by the difference in the 1 H spin density, 1 H spin-spin relaxation time (T 2 ) and diffusion coefficient (D). To develop an image, 1 H MRI non-destructively applies information about the number of water molecules in the VG from the 1 H spin density image and the mobility of water molecules in the VG from the 1 H T 2 and diffusion coefficient (D) images.…”

Section: Introductionmentioning

confidence: 99%

1H MRI study of small-diameter silk vascular grafts in water

Kuroki

Kanekiyo²,

Yazawa

et al. 2012

Polym J

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Small-diameter vascular grafts (VG) made from silk fibroin (SF) fibers by a double-raschel knitting method were prepared by coating their interior and exterior with different materials, such as SF or polyurethane (PU). The 1 H spin density, 1 H spin-spin relaxation time (T 2 ) and diffusion coefficient (D) of the water molecules in the layer of the VG coated by these materials were non-destructively observed in water using 1 H NMR imaging. The inner and outer coating materials significantly affected the amount and mobility of water molecules in the VG. The water content of the SF-coated VG was considerably higher than that of PU-coated VG. The T 2 value of the water molecules in the SF-coated VG layer was smaller than that of the PU-coated VG, which means that the rotational motion of the water molecules in the layer of the SF-coated VG was restricted by the intermolecular interaction between the SF and water molecules. The diffusion coefficient (D) of the water molecules in the SF-coated VG layer was larger than that of the PU-coated VG, indicating that the water molecules were confined to the pores in the graft layer of the PU-coated VG.

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Section: Introductionmentioning

confidence: 99%

1H MRI study of small-diameter silk vascular grafts in water

Kuroki

Kanekiyo²,

Yazawa

et al. 2012

Polym J

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Correlation study among oxygen permeability, molecular mobility, and amorphous structure change of poly(ethylene‐vinylalcohol copolymers) by moisture

Yamamoto

Kanda

Nishihara

et al. 2009

J Polym Sci B Polym Phys

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Oxygen permeability and the free‐volume hole size (cavity size) of ethylene‐vinylalcohol copolymers (EVOH) indicate abnormal humidity dependence, that is, they have minimum values in the range of around 20–40% RH, not showing a monotonic increase with humidity. To clarify this abnormal phenomenon, we investigated its molecular mobility and amorphous structure change by means of solid‐state NMR and temperature‐modulated differential scanning calorimetry (TMDSC). The glass transition temperature (Tg) decreased with humidity. Specimens stored at 15–60% RH showed large enthalpy relaxation, and it was found that the amorphous structure became more compact and the molecular conformation became more stable by ageing within this range of humidity. Under these conditions, solid‐state NMR measurement showed a component with intermediate relaxation time in the amorphous region. The results obtained by TMDSC and solid‐state NMR showed a reduction in molecular mobility by densifying in the amorphous region under the condition of 15–60% RH. The fact that the oxygen permeability and the cavity size of EVOH indicate minimum values at low humidity are attributed to the reduction in molecular mobility by enthalpy relaxation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1181–1191, 2009

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A study of solvent exchange process in (ethylene–vinyl alcohol) copolymer gels by a proton nuclear magnetic resonance spectroscopy imaging method

Cited by 2 publications

References 81 publications

1H MRI study of small-diameter silk vascular grafts in water

1H MRI study of small-diameter silk vascular grafts in water

Correlation study among oxygen permeability, molecular mobility, and amorphous structure change of poly(ethylene‐vinylalcohol copolymers) by moisture

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