Effects of the Reaction Conditions on the Formation of Cross-links in the Formalization of Poly(vinyl alcohol) Fibers

We investigated the linear dynamic viscoelasticity of dual cross-link (DC) poly(vinyl alcohol) (PVA) (DC-PVA) hydrogels with permanent and transient cross-links. The concentrations of incorporated borate ions to form transient cross-links in the DC-PVA hydrogels (CBIN) were determined by the azomethine-H method. The dynamic viscoelasticity of the DC-PVA hydrogel cannot be described by a simple sum of the dynamic viscoelasticity of the PVA gel with the same permanent cross-link concentration and the PVA aqueous solution with the same borate ion concentration (CB = CBIN) as in the DC-PVA gel. The DC-PVA hydrogel exhibited a considerably higher relaxation strength, indicating that the introduction of permanent cross-links into temporary networks increases the number of viscoelastic chains with finite relaxation times. In contrast, the relaxation frequency (ωc) (given by the frequency at the maximum of loss modulus) for the DC-PVA hydrogel was slightly lower but comparable to that for a dilute PVA solution with the same CB. This signifies that the relaxation dynamics of the DC-PVA hydrogels is essentially governed by the lifetime of an interchain transient cross-link (di-diol complex of boron). The effect of permanent cross-linking on the relaxation dynamics was observed in the finite broadening of the relaxation-time distribution in the long time region.

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Cross-links in Formalized Poly (vinyl alcohol) Fibers

The Journal of the Society of Chemical Industry Japan ◽

10.1246/nikkashi1898.74.5_1014 ◽

1971 ◽

Vol 74 (5) ◽

pp. 1014-1018

Author(s):

Hiroshi KAWASE ◽

Osamu MORIMOTO ◽

Takani MOCHIZUKI

Keyword(s):

Vinyl Alcohol ◽

Poly Vinyl Alcohol ◽

Cross Links

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Functionalization of poly(vinyl alcohol) by addition of methacryloyl groups: characterization by FTIR and NMR and optimization of reaction conditions by RSM

e-Polymers ◽

10.1515/epoly.2006.6.1.793 ◽

2006 ◽

Vol 6 (1) ◽

Cited By ~ 2

Author(s):

Edson G. Crispim ◽

Juliana F. Piai ◽

Ivânia T. A. Schüquel ◽

Adley F. Rubira ◽

Edvani C. Muniz

Keyword(s):

Reaction Time ◽

Response Surface ◽

Vinyl Alcohol ◽

Poly Vinyl Alcohol ◽

Reaction Conditions ◽

Experimental Conditions ◽

Molar Ratios ◽

Gas Bubbling ◽

Optimized Conditions ◽

Hydroxyl Hydrogen

AbstractThe modification of poly(vinyl alcohol) (PVA) with glycidyl methacrylate (GMA) in DMSO catalyzed by TEMED is reported in this paper. PVA was dissolved in DMSO and reacted with GMA at 30 ºC in a closed vessel under N2 gas bubbling for 24 hours. The reaction was characterized by FTIR and NMR (1H, 13C/DEPT and HETCOR) spectroscopies. The reaction occurs by transesterification through the insertion of methacryloyl groups into PVA chains and probably with the formation of glycidol as a by-product. The degree of substitution (DS) that represents the number of methacryloyl groups inserted was determined through 1H NMR spectra based on the ratio between the averaged area due to the vinyl hydrogen from methacryloyl groups at δ̣ 5.6 ppm and δ 6.0 ppm and the total area of the vinyl hydrogen and hydroxyl hydrogen of PVA. By use of response surface methodology the experimental conditions were optimized. The optimum conditions were 62 ºC with a reaction time of 6 hours. In these optimized conditions, the reactions using the molar ratios [-OH(PVA)/GMA] equal to 1/0.10, 1/0.25, 1/0.50, 1/0.75 and 1/1 were investigated. The response surface was based on the model DS= −19.70 + 6.09x10−1T +1.93 t − 3.89x10−3 T2 − 5.21x10−2t2 − 2.14x10−2 T * t, where T is the temperature (°C) and t the reaction time (hours). This model explained 99.20 % of the 99.64 % explainable statistical data. Using the optimized conditions, it is possible to produce a desired modified PVA, (or PVA-Ma), because DS raises linearly to the ratio [-OH(PVA)/GMA] up to 25 mol-% and the respective yield ranged from 83 to 92 %. It is difficult to obtain more than 50 mol-% substitution of PVA hydroxyl by methacryloyl groups even in these optimized conditions due to increased steric hindrance by the large number of the methacryloyl groups inserted into PVA.

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Cross-Linking of Thermally Hydrolyzed Specified Risk Materials with Epoxidized Poly (Vinyl Alcohol) for Tackifier Applications

Coatings ◽

10.3390/coatings10070630 ◽

2020 ◽

Vol 10 (7) ◽

pp. 630

Author(s):

Tao Shui ◽

Michael Chae ◽

David C. Bressler

Keyword(s):

Vinyl Alcohol ◽

Control Strategies ◽

Value Added ◽

Molar Ratio ◽

Poly Vinyl Alcohol ◽

Cross Linking ◽

Spongiform Encephalopathy ◽

Thermal Hydrolysis ◽

Reaction Conditions ◽

Infection Source

Prions have been identified as the infection source for bovine spongiform encephalopathy or ‘mad cow disease’. Safety concerns relating to this disease have led to strict feed regulations for specified risk materials (SRMs) in North America, which are characterized as the tissues in cattle where prions are likely to concentrate. As one of the approved SRM disposal methods, thermal hydrolysis converts proteinaceous materials, including prions into non-infective peptides, which have been examined for incorporation into a variety of value-added applications. Here, we describe the bio-conversion of SRM-derived peptides into tackifiers for hydro-mulch applications. Tackifiers are employed in erosion control strategies and help to bind seed and mulch to eroded areas to promote the restoration of vegetation. In this study, epoxidized poly (vinyl alcohol) (PVA) was synthesized and employed for cross-linking of SRM-derived peptides. The reaction conditions and the molar ratio of the reagents applied for the cross-linking reaction were shown to have significant effects on cross-linking behaviour. Furthermore, SRM-derived peptides that were modified with epoxidized PVA displayed viscosity, binding, and moisture maintaining capacity that were comparable to commercially available tackifiers. Hence, this research further strengthens the argument for using SRM-derived peptides as feedstock for sustainable tackifiers development.

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