Thermal Behavior Analysis of Melamine Modified Urea-Formaldehyde Resin with Different Molar Ratios

2020 ◽  
Vol 1001 ◽  
pp. 61-66
Author(s):  
Shan Feng Xu ◽  
San Shan Xia ◽  
Yu Zhu Chen ◽  
Hui Xiao ◽  
Ming Wei Jing ◽  
...  
Keyword(s):  
Activation Energy ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Molar Ratios ◽  
High Molar Ratio ◽  
Degradation Properties ◽  
Modified Urea

In this study, Thermogravimetry (TG) were used to analyze thermal degradation properties of two kinds of low-molar ratio of the melamine-modified urea-formaldehyde resin (MUF). The MUF was calculated using Kissinger equation and Flynn-Wall-Ozawa equation Resin pyrolysis activation energy. The results showed that the curing time of low mole was longer than that of MUF resin (muf-b), the content of free formaldehyde was lower, and the formaldehyde emission and wet bonding strength of plywood were reduced by 65.79% and 21.90%, respectively. TG test showed that the pyrolysis process of MUF resins with different molar ratios can be divided into three stages: dehydration, rapid pyrolysis and carbonization. At the same heating rate, the weight loss rate, peak conversion rate and carbon residue of the high molar ratio MUF resin (MUF-a) in the fast pyrolysis stage are larger than those of the MUF-b resin. The MUF-a resin pyrolysis activation energy is 166.76 kJ/mol, and the MUF-b resin pyrolysis activation energy is 95.30 kJ/mol. High molar ratio resin has higher pyrolysis activation energy and better thermal stability.

Performances of Modified Urea-Formaldehyde Resins for Bonding Plywood

2011 ◽  
Vol 71-78 ◽  
pp. 3170-3173
Author(s):  
Ji Zhi Zhang ◽  
Xiao Ying Liu ◽  
Ying Ying Qiu ◽  
Xiao Mei Wang ◽  
Jian Zhang Li ◽  
...  
Keyword(s):  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Exothermic Peak ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Formaldehyde Content ◽  
Uf Resin ◽  
Dta Curve ◽  
Modified Urea

Urea-formaldehyde resin was modified by a modifier with different synthetic processes labelled as UFM1, UFM2, and UFM3 respectively. As a comparison, normal UF resin with a F/U molar ratio of 1.1 labelled as UF0 was synthesized. The thermal behavior of modified urea-formaldehyde resins was studied by TG-DTA techniques, and the properties of plywood bonded with the UFM resins were investigated. The conclusions were as follows: (1) the modifier used in this study could significantly reduce the free formaldehyde content of urea-formaldehyde resin and the formaldehyde emission of plywood; (2) The exothermic peak temperatures of DTA curve were 129.37, 125.05, 120.98, and 116.11 °C for UF0, UFM1, UFM2, and UFM3 respectively. (3) The plywood manufactured with UFM2 and UFM3 resins have high bonding strength (1.28MPa and 1.59MPa) and low formaldehyde emission value (E1 grade).

Study on Modification of Urea Formaldehyde Resin with Keratin

2010 ◽  
Vol 113-116 ◽  
pp. 1787-1791 ◽  
Author(s):  
Jiu Yin Pang ◽  
Chuan Sun ◽  
Shi Cheng Zhang ◽  
Hai Xing Cui
Keyword(s):  
Low Cost ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Synthesis Process ◽  
Formaldehyde Resin ◽  
Low Toxicity ◽  
Modified Urea

As the main adhesive types in wood-based panel industry，urea-formaldehyde has such shortcomings as high levels of free formaldehyde content and formaldehyde emission of its bonding product. In this experiment, we try to modify urea-formaldehyde resin with keratin through copolymerization reaction. Through the determination of such reaction technology as molar ratio, adding sequence of keratin and adding amount of keratin, we finally synthesized the low toxic urea resin. The results show that the optimum molar ratio is 1.3:1, the adding amount of keratin is 5% and adding keratin after the third feeding of urea is the best choice. By optimizing the synthesis process, we ultimately get the low toxicity modified urea-formaldehyde resin. At the same time, modified urea-formaldehyde resin cost has been reduced because extensive sources of keratin and low cost.

Technics and Properties of Plywood Manufacture with Modified Urea-Formaldehyde Resin

2012 ◽  
Vol 602-604 ◽  
pp. 743-746 ◽  
Author(s):  
Xiao Mei Wang ◽  
Jian Zhang Li ◽  
Ji Zhi Zhang ◽  
Qiang Gao
Keyword(s):  
Hot Pressing ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Hot Press ◽  
Pressing Temperature ◽  
Technical Parameters ◽  
Pressing Time ◽  
Modified Urea

In this study, urea-formaldehyde resin was modified and used to bond three-ply plywood. The effect of hot press parameters on properties of plywood bonded by the modified urea-formaldehyde resin adhesive was investigated by an L(43) experimental design. The optimum technical parameters of hot press were obtained. Conclusions were as follows: (1) After modification, the free formaldehyde content of the urea-formaldehyde resin and the formaldehyde emission of resulting plywood were reduced by 74% and 70%, respectively; (2) The optimum technical parameters were 140°C of hot-pressing temperature, 80s/mm of hot-pressing time, 300g/m2 of glue content, and 0.8% of curing agent; (3) Under the optimum technical parameters, the bond strength and the formaldehyde emission of the plywood was 1.17MPa and 0.47mg/L, respectively.

Study on Modification of UFRA by Enzyme Hydrolysis Prepared Oxidized Starch

2012 ◽  
Vol 268-270 ◽  
pp. 574-579
Author(s):  
Rui Hang Lin ◽  
Xiao Bo Wang ◽  
Xiao Feng Zhu ◽  
Zhen Zhong Gao
Keyword(s):  
Enzymatic Hydrolysis ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Enzyme Hydrolysis ◽  
Curing Temperature ◽  
Impact Factors ◽  
Formaldehyde Resin ◽  
Oxidized Starch ◽  
Modified Urea

In this work, we concentrate on the preparation of oxidized starch modification reagent by enzymatic hydrolysis pretreatment, preparation of the urea-formaldehyde resin with low toxicity. The performance of modified urea-formaldehyde resin depend on the oxidation degree of oxidized starch and whether using enzymatic hydrolysis pretreatment or not. 100-PH9-HOS(the starch enzymatic hydrolysis then oxidized in 100°C with pH 9) synthetized modified urea-formaldehyde resin (100-PH9-HOS-UF) only with a free formaldehyde content of 0.14%, the lowest formaldehyde emission of 0.6078mg/L. Infrared spectroscopy test results show that samples at 3350cm-1 p-hydroxyl hydrogen bonds of association half-peak width minimum hefeng, amino-hydroxy hydrogen bond of association that samples are the weakest and with maximum cross-linking degrees; The modified urea-formaldehyde resin by oxidized starch curing properties of impact factors show that: the deeper drgree of oxidation, the higher curing temperature and the lower enthalpy.

Preparation and Formaldehyde Emission and Bonding Performance of Novel Modified Urea-Formaldehyde Resin Adhesive

2012 ◽  
Vol 490-495 ◽  
pp. 3476-3480 ◽  
Author(s):  
Zhen Zhong Gao ◽  
Chao Yue ◽  
Hai Bo Cao ◽  
Xiao Bo Wang ◽  
Xiao Feng Zhu ◽  
...  
Keyword(s):  
Bonding Strength ◽  
Adhesive Bonding ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Resin Adhesive ◽  
Bonding Performance ◽  
Addition Level

Low formaldehyde emission and high bonding strength were two basic criterions of a good urea-formaldehyde resin adhesive (UFRA). In our study, melamine modified methylolurea solution (MUS), was synthesized and used as modifier for UFRA. The bonding strength and formaldehyde emission of urea-formaldehyde resin adhesives(UFRA) were influenced by some factors such as F/U molar ratio of the main resin, F/U molar ratio of modifier, melamine content, mixing ratio of main resin with modifier, which were investigated by a series of single-factor experiments. The results showed that the best adhesive bonding strength of UFRA was 0.93MPa and the lowest formaldehyde emission was 0.43mg / L, when F/U molar ratio of the main resin was 1.5, F/U molar ratio of the MUS was 0.5, the mass fraction of melamine addition level was 5wt.% of MUS, and the mixing mass ratio of methylolurea solution (MUS) to the main UF resin was 20:80.

scholarly journals Effects of Three Biomass Fillers on the Properties of Melamine Modified Urea-Formaldehyde Resin

2020 ◽  
Vol 782 ◽  
pp. 022077
Author(s):  
Shanfeng Xu ◽  
Sanshan Xia ◽  
Yuzhu Chen ◽  
Hui Xiao ◽  
Maoyu Yi ◽  
...  
Keyword(s):  
Urea Formaldehyde ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Modified Urea

scholarly journals Calcium carbonate modified urea–formaldehyde resin adhesive for strength enhanced medium density fiberboard production

RSC Advances ◽  
2021 ◽  
Vol 11 (40) ◽  
pp. 25010-25017
Author(s):  
Li Lu ◽  
Yan Wang ◽  
Tianhua Li ◽  
Supeng Wang ◽  
Shoulu Yang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Medium Density ◽  
Ionic Bond ◽  
Resin Adhesive ◽  
Uf Resin ◽  
Modified Urea

Reactions between CaCO3 and CH2O2 during polycondensation of UF resin produce Ca2+. Ionic bond complexation binds Ca2+ with UF resin. The UF resin crystalline percentage decreases from 26.86% to 22.71%. IB strength of resin bonded fiberboard increases from 0.75 to 0.94 MPa.

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