Thermal behavior of modified urea–formaldehyde resins

Samaržija‐Jovanović, Suzana; Jovanović, Vojislav; Konstantinović, Sandra S.; Marković, Gordana; Marinović‐Cincović, Milena

doi:10.1007/s10973-010-1143-8

Cited by 103 publications

(63 citation statements)

References 13 publications

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“…2b we recorded peaks with maximum at 265 ± 2°C regardless of the modification degree of nanosilica. In this temperature the degradation of ethylene bridges also occurs [43,44]. Correspondingly, we observe 30 % mass decrement and the occurring 1-2 % differences are within margin of error.…”

Section: Resultssupporting

confidence: 70%

The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin

Dukarska

Bartkowiak

2016

J Polym Res

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The paper investigates the effect of surface modification of fumed nanosilica with (3-aminopropyl) triethoxysilane (APTES) on the kinetics and thermal stability of urea-formaldehyde (UF) resin. In the course of the investigation, nanoparticles were modified with APTES in the ratio 1, 2, 3, 4 and 5 part by weight (PBW) per 100 PBW of SiO 2 . The parameters of curing kinetics of the resin, the conversion degree and its thermal stability were determined with use of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The effect of nanosilica silanization on the curing process of resin was evaluated by determining the gel time at 100°C and the activation energy (E a ) of the crosslinking process, the initial and final temperature of the reaction (T onset , T endset ), the maximum value of the exothermic peak (T p ), the amount of emitted heat (ΔH Tp ) and the conversion degree (α Tp ) that responds to T p . With the maximum level of silica modification, we have noted a decrease in the reactivity of the resin, which is manifested by a slightly longer gel time of the resin as well as an increase in the value of activation energy of the cross-linking process. It is accompanied by a slight decrease of resin conversion degree α Tp . The modification of silica, regardless of the amount of silane inoculated on its surface, results in the increase in the thermal stability of UF resin.

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Section: Resultssupporting

confidence: 70%

The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin

Dukarska

Bartkowiak

2016

J Polym Res

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“…Only in case of the sample of MUPF resin with the addition of nanofiller small endothermic peaks were spotted at 310 and 370°C and there was a peak with a maximum value at 525°C. According to Samaržija-Jovanović et al (2011), they result from changes in the structure and loss of chemically bonded water that is included in hydroxyl groups in the form of silanol groups. The total mass decrement attained at 600°C was similar for both mixed resins and reached 85 %.…”

Section: Resultsmentioning

confidence: 99%

Fumed silica as a filler for MUPF resin in the process of manufacturing water-resistant plywood

Dukarska

Czarnecki

2015

Eur. J. Wood Prod.

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This work examines the effect of applying fumed silica with nanoscopic-size particles as a filling material for melamine-urea-phenol-formaldehyde (MUPF) resin in the process of manufacturing water-resistant plywood. Moreover, this paper investigates the possibility of reducing the amount of MUPF resin mixture used in the process of gluing veneer sheets. Based on the investigations into the reactivity, viscosity and durability of MUPF resin mixture containing various amounts of nanofiller, it was found that the optimum amount of silica that can make the resin suitable for gluing sheets of veneer amounts to 2 PBW per 100 PBW of MUPF resin. The gluing properties for thus mixed resin were determined by measuring the contact angle and determining the parameters of its derivatives, which are an additional criterion for evaluating the gluing properties. The thermal stability was tested with simultaneous use of TG-DSC analysis. The experimental plywood manufactured using optimal nano-SiO 2 was tested in terms of bond quality and mechanical properties according to appropriate standards. The investigations prove that it is possible to apply fumed silica as a filling material for the resin in the process of manufacturing water-resistant plywood. Introducing the above-mentioned amount of fumed silica into the resin makes it possible to increase the activation energy of the cross-linking process of MUPF resin and to optimize the process of gluing the sheets of veneer. Moreover, it is also possible to produce plywood of the required water-resistance with the amount of adhesive mixture reduced by 30 %.

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“…So, the isoconversional method offers E a values as a function of the degree of conversion (a) to understand a whole curing process in different steps. Thus, a change of the E a value could provide information on a curing process where a transition from kinetic-controlled reaction to diffusion-controlled reaction could occur as a increase [6].…”

Section: Activation Energy Of Liquid and Solid Uf Resinsmentioning

confidence: 99%

“…Ether bridges are converted to methylene linkages by splitting off formaldehyde molecule. After hardening, UF resins form an insoluble, three-dimensional network and cannot be melted or thermoformed again [6].…”

Section: Introductionmentioning

confidence: 99%

Comparison of thermal curing behavior of liquid and solid urea–formaldehyde resins with different formaldehyde/urea mole ratios

Nuryawan

Park

Singh

2014

J Therm Anal Calorim

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This study was undertaken to compare thermal cure kinetics of urea-formaldehyde (UF) resins, in both liquid and solid forms as a function of formaldehyde/urea (F/U) mole ratio, using multi-heating rate methods of differential scanning calorimetry. The requirement of peak temperature (T p ), heat of reaction (DH) and activation energy (E) for the cure of four F/U mole ratio UF resins (1.6, 1.4, 1.2 and 1.0) was investigated. Both types of UF resins showed a single T p , which ranged from 75 to 118°C for liquid resins, and from 240 to 275°C for solid resins. As the F/U mole ratio decreased, T p values increased for both liquid and solid resins. DH values of solid resins were much greater than those of liquid resins, indicating a greater energy requirement for the cure of solid resins. The DH value of liquid UF resins increased with decreasing in F/U mole ratio whereas it was opposite for solid resins, with much variation. The activation energy (E a ) values calculated by Kissinger method were greater for solid UF resins than for liquid resins. The activation energy (E a ) values calculated by isoconversional method which showed that UF resins in liquid or solid state at F/U mole ratio of 1.6 followed a multi-step reaction in their cure kinetics. These results demonstrated that thermal curing behavior of solid UF resin differed greatly from that of liquid resins, because of a greater branched network structure in the former.

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Thermal behavior of modified urea–formaldehyde resins

Cited by 103 publications

References 13 publications

The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin

The effect of organofunctional nanosilica on the cross-linking process and thermal resistance of UF resin

Fumed silica as a filler for MUPF resin in the process of manufacturing water-resistant plywood

Comparison of thermal curing behavior of liquid and solid urea–formaldehyde resins with different formaldehyde/urea mole ratios

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