Crystallinity and domain size of cured urea–formaldehyde resin adhesives with different formaldehyde/urea mole ratios

Park, Byung‐Dae; Causin, Valerio

doi:10.1016/j.eurpolymj.2012.10.029

Cited by 90 publications

(70 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Latex is an amorphous elastomer which is not prone to hydrolysis. The crystalline part of UF resin is also resistant to hydrolytic degradation as reported in the previous publications (Park and Jeong 2011a;2011b;2011c;Park and Causin 2013;Singh et al 2014). that they were partially covered by the latex when they were blended (Fig.…”

Section: Microstructures Of Modified Uf Resinssupporting

confidence: 62%

“…Moreover, John and Dunker (1986) and Motter (1990) stated that the UF colloidal dispersion has been shown to be partly crystalline. Further, evidence was provided that crystallinity was inherent within cured UF resins using SEM (Park and Jeong 2011a), small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXD) (Park and Causin 2013). Recently, Singh et al (2013) reported evidence of heterogeneity of cured UF resin covering up to nanoscale; coarsely granular region of UF resins that contain both globular/nodular particles and crystalline structures, as crystal aggregations and small developing crystals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructure of Cured Urea-Formaldehyde Resins Modified by Rubber Latex Emulsion after Hydrolytic Degradation

Nuryawan¹,

Park²

2014

Journal of the Korean Wood Science and Technology

Self Cite

View full text Add to dashboard Cite

This study investigated microstructural changes of cured urea-formaldehyde (UF) resins mixed with aqueous rubber latex emulsion after intentional acid etching. Transmission electron microscopy (TEM) was used in order to better understand a hydrolytic degradation process of cured UF resins responsible for the formaldehyde emission from wood-based composite panels. A liquid UF resin with a formaldehyde to urea (F/U) molar ratio 1.0 was mixed with a rubber latex emulsion at three different mixing mass ratios (UF resin to latex = 30:70, 50:50, and 70:30). The rate of curing of the liquid modified UF resins decreased with an increase of the rubber latex proportion as determined by differential scanning calorimetry (DSC) measurement. Ultrathin sections of modified and cured UF resin films were exposed to hydrochloric acid etching in order to mimic a certain hydrolytic degradation. TEM observation showed spherical particles and various cavities in the cured UF resins after the acid etching, indicating that the acid etching had hydrolytically degraded some part of the cured UF resin by acid hydrolysis, also showing spherical particles of cured UF resin dispersed in the latex matrix. These results suggested that spherical structures of cured UF resin might play an important role in hindering the hydrolysis degradation of cured UF resin.

show abstract

Section: Microstructures Of Modified Uf Resinssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Microstructure of Cured Urea-Formaldehyde Resins Modified by Rubber Latex Emulsion after Hydrolytic Degradation

Nuryawan¹,

Park²

2014

Journal of the Korean Wood Science and Technology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Solid UF resins with F/U mole ratio of 1.0 possess greater crystallinity, with larger crystallites compared to resins with higher F/U mole ratios [37,38]. Furthermore, the occurrence of simultaneous reactions among various molecular species that have their own constant activation energy could also have made contribution to the variation [31].…”

Section: Activation Energy Of Liquid and Solid Uf Resinsmentioning

confidence: 94%

Comparison of thermal curing behavior of liquid and solid urea–formaldehyde resins with different formaldehyde/urea mole ratios

Nuryawan

Park

Singh

2014

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

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 (DH) 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. DH values of solid resins were much greater than those of liquid resins, indicating a greater energy requirement for the cure of solid resins. The DH 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 a ) 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.

show abstract

“…Myers suggested that the desirability of neutralizing an acidic cure catalyst after wood bonding reduced formaldehyde liberation and increased the durability of bonded products [26]. The results of Elbert show that formaldehyde emissions from UF resins and particleboards are affected by the type and content of the catalyst [27]. However, Lee et al suggested that the amount of the hardener, which in their case varied from 0.8 to 3.2% (based on a resin with 66% solids), had practically no influence on the release of volatile acids from particleboards [28].…”

Section: Type Of Catalysts and Amount Of Catalystsmentioning

confidence: 99%

Factor Affecting Gel Time/Process-Ability of Urea Formaldehyde Resin Based Wood Adhesives

Gadhave¹,

Mahanwar²,

Gadekar³

2017

OJPChem

View full text Add to dashboard Cite

Urea-formaldehyde (UF) resin presents the most utilized adhesive system in the manufacture of plywood, particleboard and fiberboard. At the temperatures above 100˚C in the presence of hardener, this resin undergoes crosslinking reaction and the formation of three dimensional cross linked structures takes place and bonding of wood particles in a hot press [1]. UF powder resins show high reactivity and good performance in the production and by their low price; however they lack in water resistance of the hardened resin [2]. Urea-formaldehyde (UF) resins are the most important type of adhesive resins for the production of wood based panels but process-ability and curing behavior of urea formaldehyde resin depended on various factors related to resin properties, types of wood and their properties, amount & type of catalyst, types and amount of polymers addition and environmental conditions [3]. This factor decides the process-ability of UF resin based composite during manufacturing of plywood, particle board and fiberboard. In this review paper, various factors affecting gel time and process-ability of UF resin based wood composite are reviewed.

show abstract

Crystallinity and domain size of cured urea–formaldehyde resin adhesives with different formaldehyde/urea mole ratios

Cited by 90 publications

References 28 publications

Microstructure of Cured Urea-Formaldehyde Resins Modified by Rubber Latex Emulsion after Hydrolytic Degradation

Microstructure of Cured Urea-Formaldehyde Resins Modified by Rubber Latex Emulsion after Hydrolytic Degradation

Comparison of thermal curing behavior of liquid and solid urea–formaldehyde resins with different formaldehyde/urea mole ratios

Factor Affecting Gel Time/Process-Ability of Urea Formaldehyde Resin Based Wood Adhesives

Contact Info

Product

Resources

About