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Wednesday, October 14, 2020 | History

2 edition of Hydrolytic stability of cured urea-formaldehyde resins found in the catalog.

Hydrolytic stability of cured urea-formaldehyde resins

George E. Myers

Hydrolytic stability of cured urea-formaldehyde resins

by George E. Myers

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Published by Forest Products Laboratory, Forest Service, U.S. Dept. of Agriculture in [Madison, WI .
Written in English

    Subjects:
  • Urea-formaldehyde resins.

  • Edition Notes

    StatementGeorge E. Myers.
    ContributionsForest Products Laboratory (U.S.)
    The Physical Object
    Paginationp. 127-138 :
    Number of Pages138
    ID Numbers
    Open LibraryOL15310859M

      Comparative Study of Synthesis Procedures for Urea - Formaldehyde Resins (Part I) Mathew Obichukwu EDOGA 64 Keywords Urea-Formaldehyde resin, Synthesis- Procedures, Conventional method, Acid - modified procedure, Hydrolytic Stability. Introduction At present, the principal petrochemical adhesives often used in furniture industries The degradation of cured urea–formaldehyde (UF) resin in aqueous suspension was investigated by gravimetric analysis of the changes in the content of nonextractable low‐molecular components. In acid conditions (pH ) at 47°C the consecutive processes of post‐curing and of polymer break‐down (activation energy 90 kJ/mol) are detectable whereas at 80°C and 97°C only the formation of

      Full Article. Condensation Reaction and Crystallization of Urea-Formaldehyde Resin during the Curing Process. Zhongjian Ding, a, * Zhongqiang Ding, b, * Tianlin Ma, a and Hua Zhang a Urea-formaldehyde (UF) resins were synthesized with different molar ratios and solid contents, and simultaneously they were cured under conditions of different pH :// 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

    Abstract. First, phenol - formaldehyde (PF) and urea - formaldehyde (UFII) resins were separately conventionally prepared in our laboratory. Also, UF resin synthesized from the acid modified synthesis procedure was synthesized in a purely acid medium of pH , FU molar ratio of and at 50oC (one-stage acid modified-synthesis procedure). 1 Introduction Urea–formaldehyde (UF) resin adhesive is a polymeric condensation product of the chemical reaction of formaldehyde with urea, and considered as one of the most important wood adhesives among melamine–urea–formaldehyde (MUF) resins, melamine–formaldehyde (MF) resins and phenol–formaldehyde (PF) ://


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Hydrolytic stability of cured urea-formaldehyde resins by George E. Myers Download PDF EPUB FB2

Urea‐formaldehyde (UF) resins are prone to hydrolysis that results in low‐moisture resistance and subsequent formaldehyde emission from UF resin‐bonded wood panels. This study was conducted to investigate hydrolytic stability of modified UF resins as a way of lowering the formaldehyde emission of cured The hydrolytic stability of UF resins was determined by measuring the mass loss and liberated formaldehyde concentration of cured and modified UF resins after acid :// Hydrolytic stability of cured urea-formaldehyde resins.

[Madison, WI: Forest Products Laboratory, Forest Service, U.S. Dept. of Agriculture, ?] (OCoLC) Urea formaldehyde resin was developed in the s (Dinwoodie, ) and is widely used in the composites percent of the world’s particleboard is produced using UF resin (Dinwoodie, ).The advantages of UF resins were listed by Pizzi (a,b) as follows.

:// Hydrolytic stability of cured urea-formaldehyde resins. Wood Science 15(2): Nessuer, H., Schall, W. Experiments for the determination of hydrolysis phenomena in particleboards. Holzforschung Holzverwert 22(6): ?cn. This study investigated the relationship between the hydrolytic stability and the crystalline regions of cured UF resins with different formaldehyde/urea (F/U) mole ratios to better understand the hydrolysis of cured urea–formaldehyde (UF) resin adhesives responsible for its formaldehyde   A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high tempera-: tures was developed and used to assess the influ-ence of the reaction pH at synthesis on the formal-dehyde emission during cure and heat stability of the cured resins without water.

Additionally, 1 3C-CP/MAS solid-state nuclear magnetic reso- The solid residues of nine urea–formaldehyde (UF) resins after hydrolytic treatment at pH4 and 86°C for 20 h and the solid residues of one UF resin after eight different hydrolytic treatments were examined by 13 C‐CP–MAS NMR.

The relative stability toward hydrolysis of each structural component in each UF resin was established for various hydrolytic ://   Formaldehyde emission and high-temperature stability of cured urea-formaldehyde resins Received: J / Accepted: Septem Abstract A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high temperature was developed and used to assess the influence of the reaction   influence of urea-formaldehyde (UF) resin hydrolysis on formaldehyde emis- three related aspects: (a) the chemistry and hydrolytic stability of UF and phenol-formaldehyde (PF) mate- rials and rates of formaldehyde liberation from these materials, (b) the chemistry and hydrolytic sta- stable in cured resins, will degrade at a significant In an effort to understand the hydrolytic degradation process of cured urea-formaldehyde (UF) resins responsible for the formaldehyde emission of wood-based composite panels, this study analyzed the influence of acid hydrolysis on the morphology of cured UF resins with different formaldehyde/urea (F/U) mole ratios such as, and Urea formaldehyde (UF) resins are widely used thermosetting polymers in adhesives, finishes, molded objects, etc.

The existence of crystalline regions has been detected in UF resins. These crystalline regions are believed to be beneficial for the hydrolytic stability or water resistance and advanced mechanical properties of the :// Urea formaldehyde (UF) resins are widely used thermosetting polymers in adhesives, finishes, molded objects, etc.

The existence of crystalline regions has been detected in UF resins. These crystalline regions are believed to be beneficial for the hydrolytic stability The greater amount of these ordered crystallites in cured UF resins of low F/U mole ratio was found to be correlated to the improved hydrolytic stability of the cured resins.

View Show abstract The low degree of condensation and precipitation of monomeric species controls the storage stability of the MF resin. Storage temperature may be adjusted to 50°C for a longer shelf life after resin manufacture (JahromiJahromi et al.

).During storage, the aging of UF resins involves chemical changes, but MUF resins change less compared with UF resins (Siimer et al.

/Comparative-Study-of-the-Storage-Stability-between. A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high temperature was developed and used to assess the influence of the reaction pH on the formaldehyde emission and heat stability of the cured resins.

Additionally, solid-state 13C CP/MAS nuclear magnetic resonance (NMR) techniques were used to investigate the structure of cured UF resins before and after high   The degree of resin cure achievable in urea formaldehyde (UF) resin is known to influence the hydrolytic stability of UF resin.

In the current study, a significant difference in water extractable resin components has been observed between cured pure resin Hydrolytic stability and microstructure of cured urea-formaldehyde resins. Presented at the International Conference on Wood Adhesives, SeptemberHarveys Resort Hotel & ?cn.

The hydrolytically induced mass loss and formaldehyde liberation depend on the particle size of the cured resins. Additionally, more severe hydrolytic conditions (time, pH, temperature) caused elevated mass losses and formaldehyde liberations.

The hydrolytic stability of the cured resins could be well determined by gravimetric ://   dependence of urea-formaldehyde resins on formaldehyde-to-urea molar ratios at different urea concentrations and pH values, Macromolecules 25 (12) () – [15] B.-D.

Park, H.W. Jeong, Hydrolytic stability and crystallinity of cured urea–formaldehyde resin adhesives with different formaldehyde/urea mole ratios,(20)pdf. Hydrolytic stability and crystallinity of cured urea–formaldehyde resin adhesives with different formaldehyde/urea mole ratios.

Int. J. Adhesion. ; View in Article(20)  Full Article. Characterization and Application of Urea-Formaldehyde-Furfural Co-condensed Resins as Wood Adhesives. Jizhi Zhang, a,b Hui Chen, a Antonio Pizzi, b Yonghua Li, a Qiang Gao, a * and Jianzhang Li a * Furfural, as an organic compound derived from biomass materials, was used to partially substitute for formaldehyde in the synthesis of UF ://A test method for measuring formaldehyde from urea-formaldehyde (UF) resins at high temperature was developed and used to assess the influence of the reaction pH on the formaldehyde emission and heat stability of the cured resins.

Additionally, solid-state13C CP/MAS nuclear magnetic resonance (NMR) techniques were used to investigate the structure of cured UF resins before and after high