Micro-Morphological Features of Cured Urea-Formaldehyde Adhesives Detected by Transmission Electron Microscopy

Nuryawan, Arif; Singh, Adya P.; Park, Byung‐Dae; Causin, Valerio

doi:10.1080/00218464.2014.1003545

Cited by 10 publications

(2 citation statements)

References 47 publications

(67 reference statements)

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“…The method employed for the synthesis of the UF resins, as described in previously reported studies [15,21,30,31,32,33,34,35,36], was based on a traditional two-step procedure comprised of a hydroxymethylation or addition reaction followed by condensation. Using this procedure, we realized that sample purity heavily influenced the characteristics of the UF resin along with other factors such as the amount used, the sequence in which the raw materials were added, and the type of catalysts employed (i.e.,alkaline and acid catalysts).…”

Section: Characterization Of the Uf Resinsmentioning

confidence: 99%

Hydrolysis of particleboard bonded with urea-formaldehyde resin for recycling

Nuryawan

Rahmawaty

Tambun

et al. 2020

Heliyon

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In this study, the removal of urea-formaldehyde (UF) resin adhesives from waste wood particleboards (PBs) via hydrolysis was discussed, particularly the use of this application to combat environmental issues often encountered in recycling projects. Herein, the conditions required for producing PBs with poor binding properties were examined. Additionally, we determined the appropriate formaldehyde: urea (F/U) mole ratios, namely, 0.95, 1.05, and 1.15, required for generating UF resins that can be characterized and used as PB binders. The resulting values were compared with those obtained for a high mole ratio of UF resin (F/U ¼ 2.0) as well as a commercially available PB sample for binding. Aqueous hydrochloric acid (HCl) solutions of various concentrations and water were used to leach the adhesive from the wood residues, and the effectiveness of these leaching agents was determined using a combined scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) technique in addition to the Kjeldahl method. Swelling tests were performed on the UF resins to measure the sol fraction (ω sol ) and evaluate the network behavior of the resulting resins. Our results showed that factors, such as solid content, density, viscosity, and gel time, were necessary for generating an effective adhesive; herein, we determined that a solid content between 37.17 and 56.57%, density between 1.45 and 1.54 g/cm 3 , viscosity ranging from 115-444 MPa.s, and gel time between 8.50 and 13.13 min were feasible. Whereas the physical properties of the resulting PB (i.e., the density and moisture content) fulfilled the criteria established by the Japanese Industrial Standard, as laid out in the document entitled JIS A 5908: Particleboards (2003), the mechanical properties failed to pass the aforementioned standard as low bending strength and weak internal bonding were noted for the PBs produced. The use of hydrolyzing agents successfully decomposed the UF resin adhesives by altering their nitrogen (N) content; confirmation of this was obtained through SEM-EDS analysis along with the Kjeldahl method. Swelling tests showed that despite containing a reasonable amount of nitrogen owing to its dissolution in either HCl or water, the ω sol parameter was heavily influenced by the concentration of the hardener and type of F/U mole ratio adhesive used for the PB under investigation. These results indicate that wood residues can be used as raw materials for recycling PBs.

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Section: Characterization Of the Uf Resinsmentioning

confidence: 99%

Hydrolysis of particleboard bonded with urea-formaldehyde resin for recycling

Nuryawan

Rahmawaty

Tambun

et al. 2020

Heliyon

Self Cite

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“…Urea formaldehyde (UF) adhesives have the advantages of a high bonding strength, simple synthesis process, and low cost [1,2], and they have been widely used in plywood manufacturing. However, there are some obvious disadvantages of UF resin adhesives, such as poor water resistance, high brittleness of the cured adhesive layer [3,4], and high formaldehyde emissions, which have become long-standing challenges in the plywood industry [5]. Formaldehyde, a typical carcinogen which is released from UF resin products, is hazardous to human health for both resin producers and consumers [6,7].…”

Section: Introductionmentioning

confidence: 99%

The Removal of Formaldehyde from Urea Formaldehyde Adhesive by Sodium Borohydride Treatment and Its Application in Plywood

Wang,

Zhao,

Zhang

et al. 2024

Polymers

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The global production of plywood is constantly increasing as its application in the furniture and interior decoration industry becomes more widespread. An urgent issue is how to decrease the formaldehyde released from plywood, considering its carcinogenic effect on humans and harm to the environment. Reducing the free formaldehyde content of the urea formaldehyde (UF) adhesives used in the preparation process is considered an effective method. Therefore, it is necessary to identify a new type of formaldehyde scavengers. Here, the strongly reducing substance sodium borohydride was used to reduce and degrade the free formaldehyde in UF adhesives, and its effects on the properties of the UF adhesive and plywood were studied. When 0.7% sodium borohydride was added to the UF adhesive with a molar ratio of formaldehyde to urea of 1.4:1, the free formaldehyde content of the UF resin decreased to 0.21%, which is 53% lower than that of the untreated control. Moreover, the formaldehyde released from the plywood was reduced to 0.81 mg/L, ~45% lower than that from the group. The bonding strength of the treated samples could reach ~1.1 MPa, which was only reduced by ~4% compared to that of the control. This study of removing formaldehyde from UF adhesive by reduction could provide a new approach for suppressing formaldehyde release from the final products.

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