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Byung-dae Park - One of the best experts on this subject based on the ideXlab platform.
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a comparison of adhesion behavior of Urea Formaldehyde Resins with melamine Urea Formaldehyde Resins in bonding wood
Forests, 2021Co-Authors: Seongsu Park, Bora Jeong, Byung-dae ParkAbstract:This paper reports a comparison of adhesion behavior of Urea-Formaldehyde (UF) with those of melamine-Urea-Formaldehyde (MU) Resins in bonding wood by analyzing the results published in literatures. For this purpose, the adhesion behavior of UF Resins prepared by blending low-viscosity resin (LVR) with high-viscosity resin (HVR) at five different blending and two Formaldehyde/Urea (F/U) molar ratios (1.0 and 1.2) was compared with those of two MUF Resins synthesized by either simultaneous reaction (MUF-A Resins) or multi-step reaction (MUF-B Resins) with three melamine contents (5, 10, and 20 wt%). As the blending (LVR:HVR) ratio increased from 100:0 to 0:100, the viscosity and molar mass (Mw and Mn) of the blended UF Resins increased while the gelation time decreased. The interphase features such as maximum storage modulus (E′max), resin penetration depth, and bond-line thickness of the UF Resins increased to a maximum and then decreased as the blending ratio increased. In addition, both MUF-A and MUF-B Resins also showed an increase in the Mw and Mn as the melamine content increased from 5% to 20%. However, the E′max, resin penetration depth, and bond-line thickness of the MUF Resins decreased as the molar mass or melamine content increased. These results indicated that the adhesion of UF Resins heavily depends on the interphase features while that of the MUF Resins highly depends on the cohesion of the Resins.
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in situ modification of low molar ratio Urea Formaldehyde Resins with cellulose nanofibrils for plywood
Journal of Adhesion Science and Technology, 2021Co-Authors: Eko Setio Wibowo, Muhammad Adly Rahandi Lubis, Byung-dae ParkAbstract:This study describes the in-situ modification of low molar ratio Urea–Formaldehyde (UF) Resins with cellulose nanofibrils (CNFs) to improve the poor performance of Resins synthesized with different...
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effect of synthesis parameters of cold setting melamine Urea Formaldehyde Resins on the adhesion in wood bonding
Journal of Adhesion Science and Technology, 2021Co-Authors: Minseok Kim, Byung-dae Park, Soonil HongAbstract:This work studied the effect of the synthesis parameters (i.e. synthesis method and melamine content) on the adhesion of cold-setting melamine-Urea-Formaldehyde (MUF) Resins in wood bonding. Two ty...
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crystalline lamellar structure of thermosetting Urea Formaldehyde Resins at a low molar ratio
Macromolecules, 2021Co-Authors: Eko Setio Wibowo, Byung-dae ParkAbstract:Reducing Formaldehyde emission from cured Urea–Formaldehyde (UF) Resins forced us to synthesize UF Resins at a low Formaldehyde to Urea (F/U) molar ratio (≤1.0), resulting in low emission and poor adhesion by forming crystalline domains instead of building a three-dimensional network in cured Resins. For the first time, we report a crystalline lamellar structure of thermosetting UF Resins at a low molar ratio and compare it with highly amorphous UF Resins at a high F/U molar ratio (1.6). Films of crystalline and amorphous UF Resins were prepared using a spin-coater and characterized using atomic force microscopy. In addition, transmission electron microscopy, gel permeation chromatography, and X-ray diffraction were also employed for their characterization. The results showed that 1.0 UF Resins had a low molecular weight with a lamellar structure of the crystalline domain, whereas 1.6 UF Resins exhibited a high molecular weight with an amorphous structure and had a lower surface roughness. Fourier transform infrared and carbon-13 nuclear magnetic resonance spectroscopy also proved that linear molecules and hydrogen bonding were responsible for the formation of crystalline lamellar structures in thermosetting UF Resins at a low molar ratio.
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enhancing adhesion of thermosetting Urea Formaldehyde Resins by preventing the formation of h bonds with multi reactive melamine
Journal of Adhesion, 2020Co-Authors: Eko Setio Wibowo, Byung-dae ParkAbstract:Contemporary Urea-Formaldehyde (UF) Resins with low-molar-ratio contain highly crystalline domains induced by the hydrogen (H) bonds between their linear molecules, which inhibits cross-linking, an...
Eko Setio Wibowo - One of the best experts on this subject based on the ideXlab platform.
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in situ modification of low molar ratio Urea Formaldehyde Resins with cellulose nanofibrils for plywood
Journal of Adhesion Science and Technology, 2021Co-Authors: Eko Setio Wibowo, Muhammad Adly Rahandi Lubis, Byung-dae ParkAbstract:This study describes the in-situ modification of low molar ratio Urea–Formaldehyde (UF) Resins with cellulose nanofibrils (CNFs) to improve the poor performance of Resins synthesized with different...
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crystalline lamellar structure of thermosetting Urea Formaldehyde Resins at a low molar ratio
Macromolecules, 2021Co-Authors: Eko Setio Wibowo, Byung-dae ParkAbstract:Reducing Formaldehyde emission from cured Urea–Formaldehyde (UF) Resins forced us to synthesize UF Resins at a low Formaldehyde to Urea (F/U) molar ratio (≤1.0), resulting in low emission and poor adhesion by forming crystalline domains instead of building a three-dimensional network in cured Resins. For the first time, we report a crystalline lamellar structure of thermosetting UF Resins at a low molar ratio and compare it with highly amorphous UF Resins at a high F/U molar ratio (1.6). Films of crystalline and amorphous UF Resins were prepared using a spin-coater and characterized using atomic force microscopy. In addition, transmission electron microscopy, gel permeation chromatography, and X-ray diffraction were also employed for their characterization. The results showed that 1.0 UF Resins had a low molecular weight with a lamellar structure of the crystalline domain, whereas 1.6 UF Resins exhibited a high molecular weight with an amorphous structure and had a lower surface roughness. Fourier transform infrared and carbon-13 nuclear magnetic resonance spectroscopy also proved that linear molecules and hydrogen bonding were responsible for the formation of crystalline lamellar structures in thermosetting UF Resins at a low molar ratio.
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enhancing adhesion of thermosetting Urea Formaldehyde Resins by preventing the formation of h bonds with multi reactive melamine
Journal of Adhesion, 2020Co-Authors: Eko Setio Wibowo, Byung-dae ParkAbstract:Contemporary Urea-Formaldehyde (UF) Resins with low-molar-ratio contain highly crystalline domains induced by the hydrogen (H) bonds between their linear molecules, which inhibits cross-linking, an...
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converting crystalline thermosetting Urea Formaldehyde Resins to amorphous polymer using modified nanoclay
Journal of Industrial and Engineering Chemistry, 2020Co-Authors: Eko Setio Wibowo, Muhammad Adly Rahandi Lubis, Byung-dae Park, Jong Sik Kim, Valerio CausinAbstract:Abstract Thermosetting Urea–Formaldehyde (UF) Resins as the most common adhesives for wood-based composites emit Formaldehyde, which forces producers to lower Formaldehyde/Urea (F/U) molar ratio for the UF Resins synthesis. However, low-molar-ratio (below 1.0) UF Resins have low Formaldehyde emission at the expense of poor adhesion, which is responsible for the formation of crystalline domains as a result of hydrogen bonds between linear molecules. For the first time, this study reports the conversion of crystalline UF Resins to amorphous polymers by blocking the hydrogen bonds, using transition metal ion-modified bentonite (TMI-BNT) nanoclay through in situ intercalation. The modified UF Resins with 5% TMI-BNT showed an almost amorphous structure, faster curing and higher cross-linking density compared with those of neat Resins, and resulted in 56.4% increase in the adhesion strength and 48.3% reduction in the Formaldehyde emission. Thus, blocking hydrogen bonds in low F/U molar ratio UF Resins with TMI-BNT converted crystalline UF Resins to almost amorphous ones, resulting in a significant improvement in their adhesion with a low crystallinity.
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cure kinetics of low molar ratio Urea Formaldehyde Resins reinforced with modified nanoclay using different kinetic analysis methods
Thermochimica Acta, 2020Co-Authors: Eko Setio Wibowo, Byung-dae ParkAbstract:Abstract This study reports on low-molar-ratio Urea-Formaldehyde (UF) Resins modified with transition-metal-ion-modified bentonite (TMI-BNT) nanoclay assessed using different kinetic analysis methods in order to understand the effect of TMI-BNT on the cure kinetics of these modified Resins. Differential scanning calorimetry was used to determine the kinetic parameters using two types of cure kinetic analysis: 1) model-fitting (MFT) methods, which include the Kissinger and nth-order approaches, and 2) model-free kinetics (MFK) methods, including the Friedman (FR), Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) approaches. Of these kinetic methods, the Kissinger, FWO, and KAS approaches exhibited the best fit in terms of explaining the Resins’ curing behavior, showing that, in general, the apparent activation energy (Ea) decreased as TMI-BNT levels increased, which indicates that the curing process is accelerated by the addition of TMI-BNT. These results suggest that TMI-BNT is a potential additive for the effective acceleration of the curing of low-molar-ratio UF Resins and may possibly improve their adhesion as well. In addition, according to the Malek method, it is found that UF Resins curing behavior are likely to follow the autocatalytic nature of reaction.
Milena Marinoviccincovic - One of the best experts on this subject based on the ideXlab platform.
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effect of γ irradiation on the hydrolytic stability and thermo oxidative behavior of bio inorganic modified Urea Formaldehyde Resins
Composites Part B-engineering, 2015Co-Authors: Branka Petkovic, Suzana Samaržijajovanovic, Vojislav Jovanovic, Biljana Dekic, Gordana Markovic, Milena MarinoviccincovicAbstract:Abstract In order to minimize emission of Formaldehyde from Urea–Formaldehyde Resins (UF) and to improve their thermo-oxidative behavior, the effect of low γ-irradiation on hydrolytic and thermo-oxidative stability of nano-silica modified UF resin, modified UF resin with wood flour (Pinus silvestris L.) as natural filler and modified UF resin with mixture of SiO2/WF fillers were investigated. The hydrolytic stability of modified UF Resins was determined by measuring the mass loss and liberated Formaldehyde concentration of modified UF Resins after acid hydrolysis. The studied modified UF Resins have been irradiated (50 kGy) and effect of γ-irradiation was evaluated on the basis of percentage of liberated Formaldehyde before and after irradiation. The minimum percentage (1.23%) of liberated Formaldehyde and mass loss of a 25.35% were obtained in wood flour modified UF resin after γ-irradiation which indicate significant improvement in the hydrolytic stability compared to other modified UF Resins. The effect of γ-irradiation was evaluated also on the basis of thermo-oxidative behavior of the same modified UF Resins before and after irradiation. The thermo-oxidative behavior was studied by non-isothermal thermo-gravimetric analysis (TG), differential thermo-gravimetry (DTG) and differential thermal analysis (DTA) supported by data from IR spectroscopy. After γ-irradiation, the shift of DTA peaks a higher temperature indicates that thermo-oxidative stability of modified UF/SiO2/WF is increase.
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thermal behavior of modified Urea Formaldehyde Resins
Journal of Thermal Analysis and Calorimetry, 2011Co-Authors: Suzana Samaržijajovanovic, Sandra S. Konstantinović, Vojislav Jovanović, Gordana Marković, Milena MarinoviccincovicAbstract:The thermal stability of pure Urea–Formaldehyde resin (PR) and modified Urea–Formaldehyde (UF) Resins with hexamethylenetetramine-HMTA (Resin 1), melamine-M (Resin 2), and ethylene Urea (EU, Resin 3) including nano-SiO2 was investigated by non-isothermal thermo-gravimetric analysis (TG), differential thermal gravimetry (DTG), and differential thermal analysis (DTA) supported by data from IR spectroscopy. Possibility of combining inorganic filler in a form of silicon dioxide with UF Resins was found investigated and percentage of free Formaldehyde was determined. The shift of DTG peaks to a high temperature indicates the increase of thermal stability of modified UF resin with EU (Resin 3) which is confirmed by data obtained from the FTIR study. The minimum percentage (6%) of free Formaldehyde was obtained in Resin 3.
Luísa Carvalho - One of the best experts on this subject based on the ideXlab platform.
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impact of alkaline acid and strongly acid process on the synthesis of Urea Formaldehyde Resins and derived composites a comparison study
European Journal of Wood and Wood Products, 2019Co-Authors: Carolina Gonçalves, Nádia Paiva, João Ferra, João Pereira, Jorge Martins, Fernão D. Magalhães, Margarida Almeida, Ana Barrostimmons, Luísa CarvalhoAbstract:This paper presents the impact of different processes for producing Urea–Formaldehyde Resins and their roles on the physico-mechanical properties and the Formaldehyde emission of the resulting particleboards. Five Resins were produced: four via the alkaline–acid process (Resin A to D) and one using the strongly acid process (Resin E). The differences between the syntheses are mainly related to different Formaldehyde/Urea molar ratios during the synthesis, temperatures, and the number of Urea load addition. The molecular weight distribution of the Resins was monitored by gel permeation chromatography/size exclusion chromatography and the unreacted oligomers were followed by high-performance liquid chromatography. The shear strength of adhesive joints was evaluated using automated bonding evaluation system. Particleboards produced with these Resins were analyzed according to the usual standards for mechanical tests and Formaldehyde emission. The Resins differ in some characteristics, namely percentage of unreacted oligomers, chemical composition, viscosity, and reactivity. At a pressing time of 120 s, the internal bond of the particleboards was similar for all the Resins produced using the alkaline–acid process (≈ 0.60 N mm−2) but differed from that obtained using the strongly acid process (≈ 0.40 N mm−2). However, Formaldehyde emissions were apparently independent of the synthesis process.
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impact of the synthesis procedure on Urea Formaldehyde Resins prepared by alkaline acid process
Industrial & Engineering Chemistry Research, 2019Co-Authors: Carolina Gonçalves, Nádia Paiva, João Ferra, João Pereira, Luísa Carvalho, Jorge Martins, Fernão D. Magalhães, Ana BarrostimmonsAbstract:In this work, two synthesis procedures for the preparation of Urea-Formaldehyde (UF) Resins, based on the alkaline–acid process, are studied in order to better understand the chemical reactions inv...
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Impact of alkaline-acid and strongly acid process on the synthesis of Urea-Formaldehyde Resins and derived composites: a comparison study
'Springer Science and Business Media LLC', 2019Co-Authors: Carolina Gonçalves, João Pereira, Jorge Martins, Fernão D. Magalhães, Ana Barros Timmons, Margarida Almeida, Nádia T. Paiva, João M. Ferra, Luísa CarvalhoAbstract:This paper presents the impact of different processes for producing Urea-Formaldehyde Resins and their roles on the physico-mechanical properties and the Formaldehyde emission of the resulting particleboards. Five Resins were produced: four via the alkaline-acid process (Resin A to D) and one using the strongly acid process (Resin E). The differences between the syntheses are mainly related to different Formaldehyde/Urea molar ratios during the synthesis, temperatures, and the number of Urea load addition. The molecular weight distribution of the Resins was monitored by gel permeation chromatography/size exclusion chromatography and the unreacted oligomers were followed by high-performance liquid chromatography. The shear strength of adhesive joints was evaluated using automated bonding evaluation system. Particleboards produced with these Resins were analyzed according to the usual standards for mechanical tests and Formaldehyde emission. The Resins differ in some characteristics, namely percentage of unreacted oligomers, chemical composition, viscosity, and reactivity. At a pressing time of 120 s, the internal bond of the particleboards was similar for all the Resins produced using the alkaline-acid process (approximate to 0.60 N mm(-2)) but differed from that obtained using the strongly acid process (approximate to 0.40 N mm(-2)). However, Formaldehyde emissions were apparently independent of the synthesis process
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Impact of the Synthesis Procedure on Urea-Formaldehyde Resins Prepared by Alkaline-Acid Process
'American Chemical Society (ACS)', 2019Co-Authors: Carolina Gonçalves, Nádia Paiva, João Ferra, João Pereira, Jorge Martins, Fernão D. Magalhães, Ana Barros Timmons, Luísa CarvalhoAbstract:In this work, two synthesis procedures for the preparation of Urea-Formaldehyde (UF) Resins, based on the alkaline-acid process, are studied in order to better understand the chemical reactions involved. For that purpose, the number of Urea loads and the methyolation temperature were varied. The molecular weight distribution of the Resins was monitored by gel permeation chromatography/size exclusion chromatography and the unreacted oligomers by high-performance liquid chromatography, during the synthesis processes. Chemical modifications were investigated using quantitative analysis by carbon-13 nuclear magnetic resonance of samples taken during the synthesis. The largest difference identified between the procedures regards the methylene linkages and methylol groups determined by C-13 NMR. With the results of this study, it is possible to optimize the process and the properties of particleboards produced
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Highly flexible glycol-Urea-Formaldehyde Resins
European Polymer Journal, 2018Co-Authors: Ana Antunes, Nádia Paiva, João Ferra, Luísa Carvalho, Ana Barros-timmons, Jorge Martins, Fernão D. MagalhãesAbstract:Abstract Urea-Formaldehyde Resins are successfully used in many contexts, but their tightly crosslinked thermoset structure impairs some applications, due to stiff and brittle behavior. In this work we show that copolymerization of Urea and Formaldehyde with glycols introduces linear flexible segments in the polymer structure, thus increasing the resilience and flexibility of the resin after curing. Glycols with different molecular weights (106, 200 and 400 g/mol) were incorporated in the synthesis in different amounts. The chemical and physical-mechanical properties of the resulting products were investigated in detail, namely using FTIR, 13C RMN, GPC/SEC analysis, dynamic mechanical analysis, adhesive bond strength, and tensile-strain testing. Use of polyethyleneglycol with molecular weight 200 g/mol yielded the most promising glycol-Urea-Formaldehyde resin, with remarkable resilience and good adhesion properties. When used for paper impregnation, the modified Resins yielded flexible and tough papers, in comparison with a conventional Urea-Formaldehyde resin, which produced brittle papers that fractured easily upon bending.
Adya P Singh - One of the best experts on this subject based on the ideXlab platform.
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insights into the development of crystallinity in liquid Urea Formaldehyde Resins
International Journal of Adhesion and Adhesives, 2017Co-Authors: Arif Nuryawan, Byung-dae Park, Adya P Singh, M Zanetti, Valerio CausinAbstract:Abstract Differently from most thermoset materials, Urea-Formaldehyde (UF) Resins display the appearance of crystalline domains. In the effort of understanding the mechanism of formation of such crystals, wide angle X-ray diffraction (WAXD), infrared spectroscopy and transmission electron microscopy (TEM) were applied. Liquid UF Resins with two different F/U mole ratios (i.e. 1.6 and 1.0) were investigated as a function of hardener level and curing times at room temperature. The WAXD results showed that the liquid UF resin with a low F/U mole ratio had a greater crystallinity than the one with a high F/U mole ratio. An advance in crystal formation in the low F/U mole UF Resins was visible, especially in the first phases of curing. However, there were no significant differences in the degree of crystallinity as a function of hardener level. IR spectroscopy highlighted the important role of methylolated species in the formation of crystals. TEM results also confirmed the presence of crystals in all the considered liquid UF Resins. The concentration of the hardener and the curing time were critical in shaping morphology and particle dispersion. As a function of the curing conditions, the globular structures present in the samples can aggregate into different morphologies, which can be fibrillar and also lamellar. The obtained results stress the importance of controlling the subtle interplay between crosslinking and formulation for the obtainment and control of the size, quantity and morphology of crystals in UF Resins, and therefore for an effective tuning of their properties.
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comparison of thermal curing behavior of liquid and solid Urea Formaldehyde Resins with different Formaldehyde Urea mole ratios
Journal of Thermal Analysis and Calorimetry, 2014Co-Authors: Arif Nuryawan, Byung-dae Park, Adya P SinghAbstract: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 (ΔH) 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. ΔH values of solid Resins were much greater than those of liquid Resins, indicating a greater energy requirement for the cure of solid Resins. The ΔH 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 α ) 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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penetration of Urea Formaldehyde Resins with different Formaldehyde Urea mole ratios into softwood tissues
Wood Science and Technology, 2014Co-Authors: Arif Nuryawan, Byung-dae Park, Adya P SinghAbstract:In order to understand the impact of Formaldehyde/Urea (F/U) mole ratio on penetration characteristics of Urea–Formaldehyde (UF) resin into softwood tissues, a quantitative measurement of UF resin penetration into radiata pine (Pinus radiata) tissues from the bond-line was undertaken. Four different F/U mole ratios (1.6, 1.4, 1.2, and 1.0) of UF Resins with different viscosities and two levels of hardener (NH4Cl) for two extreme F/U mole ratios (1.6 and 1.0) were studied. Firstly, field emission scanning electron microscope and confocal laser scanning microscopy were used to localize UF Resins in the bond-line for the qualitative evaluation of resin penetration. Then light microscopy was employed to quantitatively measure the resin penetration and bond-line thickness. A decrease in the F/U mole ratio of UF resin that proportionately decreased the resin viscosity resulted in an increase in the average resin penetration and a decrease in the bond-line thickness. Higher hardener level provided a greater resin penetration with all F/U mole ratio UF Resins. These results demonstrated that F/U mole ratio had an impact on the penetration and bond-line thickness of UF Resins, owing to differences in the reactivity of Resins, with higher F/U mole ratio Resins being more reactive.
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hardness evaluation of cured Urea Formaldehyde Resins with different Formaldehyde Urea mole ratios using nanoindentation method
European Polymer Journal, 2013Co-Authors: Byung-dae Park, Charles R Frihart, Adya P SinghAbstract:Abstract To understand the influence of Formaldehyde/Urea ( F / U ) mole ratio on the properties of Urea–Formaldehyde (UF) Resins, this study investigated hardness of cured UF Resins with different F / U mole ratios using a nanoindentation method. The traditional Brinell hardness ( H B ) method was also used for comparison. The H B of cured UF resin films with different F / U mole ratios was determined after exposing the films to different post-curing temperatures. The nanoindentation method was employed for these films to measure Meyer hardness ( H M ) and reduced modulus ( E r ) which have been used to calculate the elastic modulus ( E s ) of cured UF Resins. As the F / U mole ratio decreased, the H B decreased continuously, indicating a less rigid network structure in low F / U mole ratio UF Resins. The higher the post-curing temperature, the greater the value of H B . The H M value also showed a similar trend as a function of F / U mole ratio. However, the E r and E s did not show a consistent trend as exhibited by H M and H B . Both H M and E r showed much greater variation in the coefficient of variation (COV) at lower F / U mole ratios 1.0 and 1.2, indicating a more heterogeneous composition of these Resins. Linear relationships between H M and E r indicate that heterogeneity of the surface composition of samples contributes greatly to variations in the measured values. This variability is discussed in terms of crystal structures present in the cured UF Resins of low F / U mole ratios.
