Dynamic Viscoelasticity of Syndiotactic Poly(vinyl alcohol) Derived from Vinyl Pivalate.

Fukae, Ryohei; Yamamoto, Tohei; Masago, Hitoshi; Kawatsuki, Nobuhiro; Sangen, Osamu; Kamachi, Mikiharu

doi:10.2115/fiber.53.5_195

Cited by 3 publications

(5 citation statements)

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“…There is a large amount of crystallite in hydrogels composed of syndiotacticity‐rich PVA. The crystallites appear to function as pseudo‐crosslinks, thereby improving the mechanical strength of the hydrogel 16, 29…”

Section: Resultsmentioning

confidence: 99%

“…The peak tan δ was observed at 69°C, which was slightly higher than that of the at‐L and at‐H gels, and broad compared with the at‐L and at‐H gels. The st‐L gel had considerably different viscoelastic behavior than the at‐L gel, although the molecules constituting the gel had nearly the same molecular weight as those constituting the at‐L gel, likely because of the formation of large amounts of pseudo‐crosslinking and the strong restraint of the molecular motion brought on by the stereoregulated sequences of the syndiotacticity‐rich PVA 11, 12, 18, 29. Unfortunately, we were unable to obtain a st‐H gel sample that was strong enough to measure its dynamic viscoelastic behavior because of the extremely low water solubility of st‐H.…”

Section: Resultsmentioning

confidence: 99%

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Effect of stereoregularity and molecular weight on the mechanical properties of poly(vinyl alcohol) hydrogel

Fukae

Yoshimura

Yamamoto

et al. 2010

J of Applied Polymer Sci

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The effect of the stereoregularity and molecular weight of poly(vinyl alcohol) (PVA) on the mechanical properties of hydrogel was investigated. Compressive strength, creep behavior, and dynamic viscoelasticity were measured on hydrogels of syndiotacticity-rich PVA derived from poly(vinyl pivalate) (Increasing the molecular weight of molecular chains constituting the gel improved the compressive strength of atactic PVA hydrogel. The stereoregularity of PVA had a greater effect than molecular weight on the strength of the hydrogel. Gel prepared from 8.8 g/dL syndiotacticity-rich PVA had a high compressive modulus of 10 kPa, and the compressive modulus of the gel prepared from 3.3 g/dL was comparable with that of atactic PVA hydrogel prepared with more than 6 g/dL. The dynamic storage modulus of the gel derived from syndiotacticity-rich PVA was remarkably higher than that of the atactic PVA gel and remained constant up to 60 C.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effect of stereoregularity and molecular weight on the mechanical properties of poly(vinyl alcohol) hydrogel

Fukae

Yoshimura

Yamamoto

et al. 2010

J of Applied Polymer Sci

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“…19 The c and c dispersions, seen at around 140 C and 220 C, occurs at temperatures well above the glass transition temperature and are attributable to the motion in the crystallites. [20][21][22][23] The decrease of E 0 at around 70 C ( Figure 1) can be used as a measure of the intensity of the a dispersion (glass transition). This decrease becomes smaller on the increase of annealing temperature, which suggests that the content of the non-crystalline component decreases (and thus the degree of crystallinity c increases) on sufficient annealing.…”

Section: Resultsmentioning

confidence: 99%

“…For LI-PVA having a fairly large mm value (¼ 0:44), the c dispersion seems to be clearly resolved for the same reason. In contrast, for S-PVA, the c dispersion peak vanishes possibly because the strong intermolecular forces due to syndiotactic regulation 23 (and lack of significant intramolecular hydrogen bonding) hardly changes with the cell expansion. For A-PVA, the lack of the clear c dispersion peak can be also attributed to a similarly strong intermolecular forces as well as to high ordering in crystallites in A-PVA film, the latter resulting from the lamellar thickening on high-temperature annealing (i.e.…”

Section: Comparison Of Hi-pva S-pva and A-pva Filmsmentioning

confidence: 93%

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Highly Isotactic Poly(vinyl alcohol) Derived from tert-Butyl Vinyl Ether V. Viscoelastic Behavior of Highly Isotactic Poly(vinyl alcohol) Films

Ohgi

Sato

Watanabe

et al. 2006

Polym J

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ABSTRACT:Dynamic viscoeasticity of poly(vinyl alcohol) with high isotacticity (HI-PVA, mm ¼ 0:78), being derived from tert-butyl vinyl ether, was investigated to compare with that of syndiotactc PVA (S-PVA, mm ¼ 0:14) and commercial atactic PVA (A-PVA, mm ¼ 0:22). In the non-crystalline region, the a (local twisting motion) and a (micro-Brownian motion) dispersions occurring at around À10 C and 70 C were nearly the same, in both magnitude and location, for the HI-PVA and S-PVA having an almost identical degree of crystallinity. On the other hand, in the crystalline region, the c and c dispersions of HI-PVA were somewhat different from those of ordinary PVAs. The c dispersion (local motion in crystals due to defects) was clearly observed for HI-PVA but not for S-PVA and A-PVA. The c dispersion (axial motion of the chain in the crystal lattices) was observed for all PVA films but its temperature increased in the order of HI-PVA > S-PVA > A-PVA, which well corresponded to the order of the melting temperature and 13 C spin-lattice relaxation time (T 1C ) of each stereoregular PVA. These differences may be attributed to a difference of the magnitude of intermolecular and/or intramolecular hydrogen bonding in the crystals of respective PVAs. Specifically, the successive intramolecular bonding in the HI-PVA crystal appears to reduce the magnitude of the intermolecular bonding thereby allowing the chain to exhibit the c motion. This successive bonding would also stiffen the chain backbone thereby increasing the c dispersion temperature. [doi:10.1295/polymj.PJ2005235] KEY WORDS Highly Isotactic Poly(vinyl alcohol) / Stereoregular Polymerization / Viscoelasticity / Many efforts have been made for synthesis of stereoregular poly(vinyl alcohol)s (PVAs) being rich in syndiotactic or isotactic sequences 1-3 and changes of their physical properties with the stereoregularity, possibly reflecting changes in the inter-and intramolecular hydrogen bonding, have been extensively investigated. A series of radical-polymerized poly(vinyl ester)s was utilized to synthesize syndiotactic PVAs, and the relationships between stereoregularity and physical properties of PVA have been examined. 1-3Isotactic PVAs were synthesized successfully from poly(vinyl ether)s such as poly(benzyl vinyl ether) (PBzVE), 4,5 poly(tert-butyl vinyl ether) (PtBVE), 6,7 and poly(trimethyl silyl vinyl ether) (PVOSi), 8,9 and their physical properties were also investigated. 1,3Despite the above efforts, the stereoregularity still remained at a low level of the mm fraction (¼ 0:70) even for so-called isotactic PVA (LI-PVA) derived from PVOSi.9,10 Recently, we studied the cationic polymerization of tBVE with boron trifluoride diethyl etherate (BF 3 . OEt 2 ) and successfully prepared the PVAs having the highest isotacticity so far reported. [10][11][12] We found interesting features of these highly isotactic PVAs (HI-PVAs) being different from those of LI-PVA and ordinary atactic PVA (A-PVA). 10,13,14 In particular, we compared the melting temperature T m , degree...

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The effect of casting solvent on the structural characteristics and miscibility of regenerated silk fibroin/Poly(vinyl alcohol) blends

Park

2007

Fibers Polym

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Dynamic Viscoelasticity of Syndiotactic Poly(vinyl alcohol) Derived from Vinyl Pivalate.

Abstract: Dynamic viscoelasticity of polyvinyl alcohol)

Cited by 3 publications

References 0 publications

Effect of stereoregularity and molecular weight on the mechanical properties of poly(vinyl alcohol) hydrogel

Effect of stereoregularity and molecular weight on the mechanical properties of poly(vinyl alcohol) hydrogel

Highly Isotactic Poly(vinyl alcohol) Derived from tert-Butyl Vinyl Ether V. Viscoelastic Behavior of Highly Isotactic Poly(vinyl alcohol) Films

The effect of casting solvent on the structural characteristics and miscibility of regenerated silk fibroin/Poly(vinyl alcohol) blends

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