Study on Curing Characteristics of Low-Toxicity Urea-Formaldehyde Resin

2011 ◽  
Vol 393-395 ◽  
pp. 1447-1450
Author(s):  
Shu Min Wang ◽  
Jun You Shi
Keyword(s):  
Activation Energy ◽  
Urea Formaldehyde ◽  
Formaldehyde Resin ◽  
Test Results ◽  
Hot Press ◽  
Curing Reaction ◽  
Uf Resin ◽  
Curing Characteristics ◽  
Low Toxicity ◽  
Hot Press Process

Curing characteristics of low-toxicity urea-formaldehyde (UF) resin in different curing system were studied by differential scanning carlorimetry (DSC). Test results showed that the initial orterminal temperature and activation energy needed of curing reaction for low-toxicity UF resin were different in different curing system. The initial temperature of curing reaction for low-toxicity UF resin and activation energy were the lowest, and exotherm was most under curing system C, which showed the acceleration of curing system C on low-toxicity UF resin was best. The appropriate curing system can be optimized and applied for hot-press process in practical production by means of DSC to investigate curing characteristics of low-toxicity UF resin.

The Effect of the pH Value of Wood on the Curing Reaction of Low Toxic Urea-Formaldehyde Resin

2010 ◽  
Vol 150-151 ◽  
pp. 1263-1266
Author(s):  
Li Bin Zhu ◽  
Ji You Gu ◽  
Yan Hua Zhang ◽  
Jun Shen
Keyword(s):  
Ph Value ◽  
Wood Flour ◽  
Urea Formaldehyde ◽  
Onset Temperature ◽  
Peak Temperature ◽  
Formaldehyde Resin ◽  
Scanning Calorimetry ◽  
Curing Reaction ◽  
Uf Resin ◽  
Low Toxic

The differential scanning calorimetry(DSC) was used to study the curing reaction of low toxic UF resin with poplar, birch, larch powder in different pH value. The results showed that the effect of different wood flour and its pH value on the curing reaction of UF resin was not the same. Along with the increase of the pH, the peak temperature and the onset temperature was raised; the peak temperature and the onset temperature of poplar was higher than that of the birch. The tempera- ture of the curing reaction of UF resin modified by melamine was higher than the UF resin without modification.

scholarly journals Study on the Pyrolysis Behaviors of Urea-Formaldehyde Resin and Rice Straw Mixed Pellets

2022 ◽  
Vol 9 ◽  
Author(s):  
Xiaoteng Li ◽  
Huilin Bing ◽  
Siyi Luo ◽  
Weiwei Zhang ◽  
Zongliang Zuo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Rice Straw ◽  
Urea Formaldehyde ◽  
Liquid Product ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Mass Ratio ◽  
Pyrolysis Process ◽  
Pyrolysis Kinetics ◽  
Uf Resin

In order to study the effect of biomass on the pyrolysis characteristics of urea-formaldehyde resin, the thermogravimetric experiments were carried out respectively using urea-formaldehyde resin (UF), rice straw (RS), and their mixed pellets with different proportions. The pyrolysis kinetics analysis was conducted. The results showed that the pyrolysis process of UF resin and mixed pellets could be divided into three stages: the drying and dehydration of the material, the rapid decomposition of volatile matter, and residue decomposition. The reaction order of UF resin and mixed pellets was discussed using the Coats–Redfern method, the activation energy of UF resin was 54.27 kJ/mol, and this value decreased with the addition of rice straw. As the mass ratio of UF resin to rice straw was 3:1, the activation energy achieved the lowest value, which means that the addition of rice straw was beneficial to the pyrolysis process of UF. In the process of pellet preparation, the falling strength and compressive strength of UF resin pellets can be improved by adding an appropriate proportion of rice straw. In this test, the yield of pyrolytic carbon reached the highest value of 23.93%, as the mass ratio of UF resin to rice straw was 3:2. When the mass ratio was 4:1, the highest liquid product yield of 43.21% was achieved.

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.

Effect of calcite addition on technical properties and reduction of formaldehyde emissions of medium density fiberboard

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3718-3733
Author(s):  
Osman Camlibel
Keyword(s):  
Liquid Paraffin ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Wood Fibers ◽  
Hot Press ◽  
Ammonium Sulphate Solution ◽  
Hot Press Process

Physical, mechanical, and formaldehyde emission properties were studied for medium density fiberboard (MDF) produced with oak (75%) and pine (25%) fibers that had been mechanically refined in the presence of calcite particles. The calcite slurry was prepared at two levels of solids, 1.5% and 3% (10 and 20 kg·m-³). Chips were cooked for 4 min at 185 °C, under 8 bar vapor pressure in an Andritz defibrillator. 1.8% liquid paraffin, 0.72% ammonium sulphate solution, and 11% urea-formaldehyde were added by percentage based on oven-dried wood fibers in the blowline at the exit of the defibrator. The fibers were dried to 11% moisture content. MDF boards (2100 mm × 2800 mm × 18 mm) were created using a continuous hot-press process. The addition of calcite in the course of MDF production resulted in improved physical properties, such as thickness swelling (ThS 24 hours) and water absorption (WA 24 hours). MDF boards prepared with calcite exhibited higher internal bond (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Resistance to axial withdrawal of screw also was increased by addition of 3% calcite. In addition, the lowest levels of formaldehyde emission were observed for MDF prepared with calcite at the 3% level.

scholarly journals Improving Thermal Conductivity Coefficient in Oriented Strand Lumber (OSL) Using Sepiolite

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 599 ◽  
Author(s):  
Hamid R. Taghiyari ◽  
Abolfazl Soltani ◽  
Ayoub Esmailpour ◽  
Vahid Hassani ◽  
Hamed Gholipour ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Core Temperature ◽  
Thermal Conductivity Coefficient ◽  
Urea Formaldehyde ◽  
Wood Products ◽  
Raw Material ◽  
Formaldehyde Resin ◽  
The Core ◽  
Uf Resin ◽  
Hardness Values

An issue in engineered wood products, like oriented strand lumber (OSL), is the low thermal conductivity coefficient of raw material, preventing the fast transfer of heat into the core of composite mats. The aim of this paper is to investigate the effect of sepiolite at nanoscale with aspect ratio of 1:15, in mixture with urea-formaldehyde resin (UF), and its effect on thermal conductivity coefficient of the final panel. Sepiolite was mixed with UF resin for 20 min prior to being sprayed onto wood strips in a rotary drum. Ten percent of sepiolite was mixed with the resin, based on the dry weight of UF resin. OSL panels with two resin contents, namely 8% and 10%, were manufactured. Temperature was measured at the core section of the mat at 5-second intervals, using a digital thermometer. The thermal conductivity coefficient of OSL specimens was calculated based on Fourier’s Law for heat conduction. With regard to the fact that an improved thermal conductivity would ultimately be translated into a more effective polymerization of the resin, hardness of the panel was measured, at different depths of penetration of the Janka ball, to find out how the improved conductivity affected the hardness of the produced composite panels. The measurement of core temperature in OSL panels revealed that sepiolite-treated panels with 10% resin content had a higher core temperature in comparison to the ones containing 8% resin. Furthermore, it was revealed that the addition of sepiolite increased thermal conductivity in OSL panels made with 8% and 10% resin contents, by 36% and 40%, respectively. The addition of sepiolite significantly increased hardness values in all penetration depths. Hardness increased as sepiolite content increased. Considering the fact that the amount of sepiolite content was very low, and therefore it could not physically impact hardness increase, the significant increase in hardness values was attributed to the improvement in the thermal conductivity of panels and subsequent, more complete, curing of resin.

The Impact of Different Dosage of Additives on the UF Resin Used in Plywood

2011 ◽  
Vol 197-198 ◽  
pp. 147-150 ◽  
Author(s):  
Wei Wang ◽  
Li Bin Zhu ◽  
Ji You Gu ◽  
Xiang Li Weng ◽  
Hai Yan Tan
Keyword(s):  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Synthetic Process ◽  
Resin Adhesive ◽  
Environmental Friendly ◽  
Uf Resin ◽  
Comprehensive Performance ◽  
The Impact

Through the study of the effects of different dosage of additives on the properties of urea formaldehyde resin adhesive prepared at low mole ratio of formaldehyde/urea, optimize the synthetic process of the UF resin which is used at the E0 grade plywood. The results showed that the product synthesized under the following condition: the mole ratio of formaldehyde/urea is 0.99:1, the dosage of the specific additive is 1.0% and that of melamine is 3-4%, had a good comprehensive performance and the formaldehyde emission of the plywood meets the E0 grade which is environmental-friendly.

scholarly journals Reduction of formaldehyde emission from urea-formaldehyde resin with a small quantity of graphene oxide

RSC Advances ◽  
2021 ◽  
Vol 11 (52) ◽  
pp. 32830-32836
Author(s):  
Kazuki Saito ◽  
Yasushi Hirabayashi ◽  
Shinya Yamanaka
Keyword(s):  
Graphene Oxide ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Urea Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Uf Resin

This is the first experiment to demonstrate that GO effectively prevents formaldehyde emission from UF resin.

scholarly journals Process modification involving strong-acid step in urea-formaldehyde resin preparation

2020 ◽  
Vol 16 (2) ◽  
pp. 212-217
Author(s):  
Dicky Dermawan ◽  
Lucky William Kusnadi ◽  
Jemmy Lesmana
Keyword(s):  
Urea Formaldehyde ◽  
Gelation Time ◽  
Strong Acid ◽  
Raw Material ◽  
Molar Ratio ◽  
Formaldehyde Resin ◽  
Formaldehyde Concentration ◽  
Formaldehyde Content ◽  
Process Modification ◽  
Uf Resin

Urea-formaldehyde (UF) resin adhesive for wood-based panel industries are commonly manufactured using conventional alkaline-acid process. This paper reports a process modification of a conventional UF resin preparation by incorporating a strong-acid step, involving simultaneous methylolation and condensation reactions at very low pH at the beginning of the processing step. The experiment showed that this additional step should be carried out at short duration and at high enough temperature in order to avoid gelation or separation problems. In order to control temperature rise caused by the exothermic nature of the reactions, the modified process requires a higher initial formaldehyde-to-urea (F/U) molar ratio compared to the original. For the same reason, the first urea should be fed incrementally to ensure high F/U ratio at any time during the strong acid step. Using regular formalin concentration as raw material at the same F/U molar ratio, the modified resin showed lower free formaldehyde content thus have lower reactivity in comparison to those of the original. However, when the same procedure was applied using higher formaldehyde concentration at higher solid content, the produced resin showed comparable free formaldehyde content and shorter gelation time. Application test for making plywood showed that the modified process gave a very significant improvement in both the internal bonding strength and formaldehyde emission.

scholarly journals Urea Formaldehyde Resin Resultant Plywood with Rapid Formaldehyde Release Modified by Tunnel-Structured Sepiolite

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1286 ◽  
Author(s):  
Li ◽  
Gao ◽  
Xia ◽  
Li ◽  
Zhou
Keyword(s):  
Shear Strength ◽  
Fracture Surface ◽  
Cross Section ◽  
Urea Formaldehyde ◽  
Formaldehyde Emission ◽  
Formaldehyde Resin ◽  
Tunnel Structure ◽  
Formaldehyde Release ◽  
Uf Resin ◽  
The Cost

In order to reduce the cost of plywood and save edible resources (wheat flour), a cheap and resourceful clay, sepiolite, was used to modify urea formaldehyde (UF) resin. The performances of filler-filled UF resins were characterized by measuring the thermal behavior, cross section, and functional groups. Results showed that cured UF resin with SEP (sepiolite) formed a toughened fracture surface, and the wet shear strength of the resultant plywood was maximum improved by 31.4%. The tunnel structure of SEP was beneficial to the releasing of formaldehyde, as a result, the formaldehyde emission of the plywood bonded by UF resin with SEP declined by 43.7% compared to that without SEP. This study provided a new idea to reduce the formaldehyde emission, i.e. accelerating formaldehyde release before the product is put into use.

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