Formation of Linear Polyenes in Thermal Dehydration of Polyvinyl Alcohol, Catalyzed by Phosphotungstic Acid

Третинников, О. Н.; Sushko, N. I.

doi:10.1007/s10812-015-0048-5

Cited by 11 publications

(11 citation statements)

References 8 publications

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“…The second stage (II) is mainly the removal of hydroxyl groups. And a double bond is generated accompanied by a side reaction 36 . In the third stage (III), a severe degradation reaction begins, and small molecule fragments, such as, aldehydes, ketones, esters, and carboxylic acids are formed 37 …”

Section: Resultsmentioning

confidence: 99%

“…And a double bond is generated accompanied by a side reaction. 36 In the third stage (III), a severe degradation reaction begins, and small molecule fragments, such as, aldehydes, ketones, esters, and carboxylic acids are formed. 37 The weight loss in the fourth stage (IV) is attributed to the fracture and cyclization of the macromolecular C C backbone.…”

Section: Dsc and Tg Analysismentioning

confidence: 99%

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Ultra‐low degree of polymerization polyvinyl alcohol products prepared by oxidative chain scission: Method and mechanism

Song

Deng

Zhang

2021

J of Applied Polymer Sci

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In this paper, the high value‐added (ultra‐low degree of polymerization [ULDP]) polyvinyl alcohol (PVA) product was successfully prepared by oxidative chain scission method with sodium hypochlorite as an oxidant. When the molar ratio of PVA to NaClO is not less than 1:1.8, the reaction is stirred for several hours (≥2 h) at a temperature not exceeding 50°C. After precipitation and washing in methanol, PVA with polymerization degree of 38–150 can be obtained after drying. The infrared spectrum (IR) and nuclear magnetic hydrogen spectrum (1H‐NMR) test proved that the product obtained by this method is indeed PVA. The results of 1H‐NMR also showed that the chain broken has no selectivity and the stereoregularity of hydroxyl group did not change significantly. Through radical quenching experiment and electron paramagnetic resonance (EPR) analysis, it is proved that OCl− is the main active oxide, ·Cl makes the oxidative chain scission process can be realized quickly, and ·OH is an indispensable factor for obtaining ULDP PVA. Under the combined action of these three, high value‐added PVA with ULDP was successfully prepared. Additionally, the sodium hypochlorite oxidized the ·OH captured by 5,5‐dimethyl‐1‐pyrroline‐n‐oxide (DMPO‐OH) to 2‐hydroxy‐5,s‐dimethyl‐1‐pyrroline‐N‐oxide (HDMPO‐OH) in an alkaline environment.

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Section: Resultsmentioning

confidence: 99%

Section: Dsc and Tg Analysismentioning

confidence: 99%

Ultra‐low degree of polymerization polyvinyl alcohol products prepared by oxidative chain scission: Method and mechanism

Song

Deng

Zhang

2021

J of Applied Polymer Sci

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“…In order to crosslink the PVA samples with the GA, heat treatment of these films was carried out. Such heat treatment may lead to the elimination of hydroxyl groups to some extent from PVA in the form of water molecules which results in the formation of polyene (C=C) structures in the polymer chain [41,42] . FTIR spectra of the composite samples show slight downshift in the -OH band position (highlighted by dashed line in Figure 2(A)), suggesting the formation of hydrogen bonds between the fillers and the matrix [32,43] .…”

Section: Resultsmentioning

confidence: 99%

Synergistic effect of crosslinking and dual reinforcement on the thermal and mechanical properties of polyvinyl alcohol

et al. 2020

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We examined the combined effect of crosslinking and dual reinforcement on the thermal and mechanical properties of polyvinyl alcohol (PVA). Glutaric acid (GA) was used as crosslinker while tungsten disulfide nanotubes (WSNT) and carboxylated multiwall carbon nanotubes (f-MWCNT) were used as dual reinforcing agents. Tensile strength and toughness of the hybrid composite, that is, crosslinked PVA reinforced with both f-MWCNT and WSNT, was higher than those of neat PVA, crosslinked PVA, crosslinked PVA reinforced with WSNT and crosslinked PVA reinforced with f-MWCNT. The hybrid composite showed remarkable improvement over neat PVA: tensile strength increased by 138%, Young's modulus increased by 142%, and toughness increased by 246%. Water uptake tendency and thermal stability of the composites were also examined and compared. The advantage of using dual reinforcement was a simultaneous increment in tensile strength and toughness, similar to what is observed in some natural materials like nacre. K E Y W O R D S carbon nanotubes and tungsten disulfide nanotubes, crosslinking, polymer-nanocomposites, thermal and mechanical properties

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“…The very weak band at 1743 cm −1 is probably due to the stretching of C=O bonds from acetate groups remaining in PVA (incomplete hydrolysis of the polyvinyl acetate during PVA synthesis). The bands at 1382 and 1326 cm −1 can be attributed to stretching vibrations of C-N bonds in aminophosphonic acids [30] and free P=O bonds [7,31], respectively. The band at 1082 cm −1 is assigned to the ν as (P-O) stretching modes of the central PO 4 tetrahedron in [PW 9 O 34 ] 9− anion [25].…”

Section: Ir Spectroscopic Studymentioning

confidence: 99%

“…The broad band at 3243 cm −1 can be assigned to the OH stretching vibrations of hydrogen bonded OH-groups of phosphonic acids and H 3 O + ion [30][31][32][33]. On the one hand, the presence of vibrations of W=O and W-O-W bonds belonging to the free [PW 9 O 34 ]grouping (in organophosphoryl derivates of tri-vacant tungsto-phosphates, these vibrations are shifted to the region of higher wave numbers [25]) indicates their direct bonding to PVA backbone via C-O-W bridges formation; on the other hand, the strong asymmetric bending O-P-O vibrations, which are characteristic for organophosphoryl derivates of [PW 9 O 34 ] 9− anion [25], indicate on the similar derivate formation.…”

Section: Ir Spectroscopic Studymentioning

confidence: 99%

Tailor-Made Phosphorylated Polyvinyl Alcohol/Tungsten Polyoxometalate Proton Exchange Membrane for a Bio-Electrochemical Energy Storage System

et al. 2021

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In this work, the synthesis of a phosphorylated polyvinyl alcohol (p-PVA)/polyoxometalate (tungsto-phosphate) membrane for the BioGenerator, a bio-electrochemical energy storage technology, is reported. It was shown that bonding of lacunary tungsto-phosphate ions to the carbon skeleton of a polymer matrix results in an increase in proton conductivity of up to 2.7 times, compared to previously studied phosphorylated PVA membranes. Testing of the membrane in an actual Fe3+/H2 electrochemical cell showed that it performs significantly better (0.28 W·cm−2 at 0.79 A·cm−2) than the previously used commercial Selemion HSF (Japan) membrane (0.18 W·cm−2 at 0.60 A·cm−2).

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Formation of Linear Polyenes in Thermal Dehydration of Polyvinyl Alcohol, Catalyzed by Phosphotungstic Acid

Cited by 11 publications

References 8 publications

Ultra‐low degree of polymerization polyvinyl alcohol products prepared by oxidative chain scission: Method and mechanism

Ultra‐low degree of polymerization polyvinyl alcohol products prepared by oxidative chain scission: Method and mechanism

Synergistic effect of crosslinking and dual reinforcement on the thermal and mechanical properties of polyvinyl alcohol

Tailor-Made Phosphorylated Polyvinyl Alcohol/Tungsten Polyoxometalate Proton Exchange Membrane for a Bio-Electrochemical Energy Storage System

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