Practical relationship between apparent viscosity and molecular weight of urea-formaldehyde resin adhesives

Jeong, Bora; Park, Byung‐Dae

doi:10.1080/01694243.2018.1529282

Cited by 8 publications

(7 citation statements)

References 13 publications

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“…Obviously, the molecular weight values of MA-PDMS are all larger than that of the PDMS, which suggests that the cross-linker KH571 and PDMS have been polymerized . The molecular weights of M2, M3, and M4 composed of two compositions are not determined in this work because the viscosity can reflect the average molecular weight; the higher the viscosity of the mixture is, the higher its average molecular weight is. − As displayed in Figure , with the increase in the proportion of the high-molecular-weight MA-PDMS, the viscosity of M x exhibits an increasing tendency from 2.15 to 17.5 Pa·s. This is due to an increase in the entanglement density, and it leads to a reduction in chain mobility .…”

Section: Results and Discussionmentioning

confidence: 92%

High-/Low-Molecular-Weight PDMS Photo-Copolymerized Membranes for Ethanol Recovery

Liu

et al. 2023

Ind. Eng. Chem. Res.

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Poly(dimethylsiloxane) (PDMS) is the benchmark of alcohol-selective membranes. The low-molecular-weight PDMS easily causes pore penetration and nonuniform coverage, thus PDMS membrane is generally fabricated by the high-molecular-weight chains (M w ≥ 50,000). However, there are inevitably excessive chain entanglements in longer polymeric chains, limiting the transport of penetrating molecules. In this work, we proposed a high-/low-molecular-weight PDMS photo-copolymerized strategy to prepare a high-performance pervaporation membrane for ethanol recovery, which combines the advantages of high-/low-molecularweight PDMS chains. The fluidity and polymerization efficiency are improved, while the excessive pore penetration is prevented. The result showed that the high-/low-molecular-weight PDMS mixed membranes display a superior comprehensive pervaporation performance for ethanol recovery in comparison with the other polymeric membranes. The copolymerized strategy is facile and shows a promising prospect for ethanol recovery.

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Section: Results and Discussionmentioning

confidence: 92%

High-/Low-Molecular-Weight PDMS Photo-Copolymerized Membranes for Ethanol Recovery

Liu

et al. 2023

Ind. Eng. Chem. Res.

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“…Then the viscometric flow times were measured for the samples. By using measured flow time of a solution, viscosity is calculated by Poiseuille's law at following equation [13]:…”

Section: Molecular Weight Determinationmentioning

confidence: 99%

“…Nevertheless, phenol formaldehyde belongs phenolic resin is comparatively harmful to the environment [12]. Moreover, it is better to use urea formaldehyde because it is cheap in price, possess good quality, less foul-smelling and has a beautiful color [5], [13]- [14].…”

Section: Introductionmentioning

confidence: 99%

“…For blending with other materials purposes, it is also important to apply the resin in a liquid state. The use ability of liquid resin is depended on its viscosity [13], [23]- [24]. The low viscous resin can penetrate and spread easily on broad panel when use in adhesive purposes.…”

Section: Introductionmentioning

confidence: 99%

“…The molecular weight of UF resin were measured by using gel permeable chromatography (GPC), NMR, viscometry etc. [13], [26]. Viscometry is very simple technique which able to provide important information of viscous polymer solution [27].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Synthesis Conditions on the Molecular Weight and Activation Energy of Urea-formaldehyde Prepolymer and Their Relationship

Anjum

Khan

2020

JEA

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The aim of this study is to find out the viscosity change of urea-formaldehyde (UF) resin with the synthesis parameters namely formaldehyde/urea (F/U) mole ratios, pH and temperature. The viscosity of UF resins, related to molecular weight and activation energy is very important factor of their usability. Urea-formaldehyde (UF) prepolymer was synthesized through polycondensation reaction with F/U ratio 0.8, 1.0, 1.2, 1.4, 1.6. The synthesis was carried out by two steps: alkali catalysis at reaction pH 8.3, 90°C for 60 min and thereafter acid catalysis at pH 4.3, 83°C for 15 min. Viscosity of prepolymer was determined at acid catalysis step by simple glass viscometer. Weight average molecular weight (Mw) was calculated from the viscosity data of UF prepolymer using Mark-Houwink equation. Highest Mw (2020.9) of prepolymer was obtained at F/U molar ratio 1.0 and pH 4.3. In addition, it was found that pH 4.0 yielded greater Mw (2049) UF prepolymer among the four reactions which were performed at pH 4.0, 4.3, 4.7, and 5.0. The energy of activation (Ea) of UF prepolymer was also calculated from the measured viscosity at temperature 70, 75, 80 and 85°C. The highest values of Ea were also found at F/U molar ratio 1.0 and pH 4.0 & lowest values was obtained at F/U molar ratio 1.6 and pH 5.0. From the experimental data, it was shown that the values of Ea and Mw were varied comparably with the change of reaction parameters.

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Thermal degradation kinetics of high‐performance urea‐formaldehyde resin prepared by replacing partial urea with soybean processing residue

He,

Guo,

Zhao

et al. 2023

J of Applied Polymer Sci

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In this work, soybean meal was applied to replace partial urea to prepare high‐performance urea‐formaldehyde resin (SMUF). The optimum addition amount of soybean meal was screened by the basic properties of resin, the bonding strength and formaldehyde emission of the board. The activation energy (Ea) and reaction kinetics at different conversion rates were estimated by Kissinger and Flynn–Wall–Ozawa methods. The results showed that when 5 wt% soybean meal was used to replace urea, the formaldehyde emission of plywood decreased by 19.23% and the bonding strength increased by 36.29%, which were 0.84 mg L−1 and 1.69 MPa, respectively. Meanwhile, the thermal stability of Urea‐formaldehyde (UF) resin is improved. The thermal degradation Ea of SMUF is higher than that of UF, the reaction kinetic equation of both UF and SMUF are G(α) = [−ln (1 − α)]2. It is feasible to replace partial urea with soybean meal. When the addition level of soybean meal is 5 wt%, SMUF has better comprehensive performance. When the addition level of soybean meal is 10–20 wt%, the bonding strength of plywood is higher than that of UF, but the formaldehyde emission is higher. How to reduce the formaldehyde emission will be the direction of future research.

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Practical relationship between apparent viscosity and molecular weight of urea-formaldehyde resin adhesives

Cited by 8 publications

References 13 publications

High-/Low-Molecular-Weight PDMS Photo-Copolymerized Membranes for Ethanol Recovery

High-/Low-Molecular-Weight PDMS Photo-Copolymerized Membranes for Ethanol Recovery

Effect of Synthesis Conditions on the Molecular Weight and Activation Energy of Urea-formaldehyde Prepolymer and Their Relationship

Thermal degradation kinetics of high‐performance urea‐formaldehyde resin prepared by replacing partial urea with soybean processing residue

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