Bonding kinetics of thermosetting adhesive systems used in wood-based composites: the combined effect of temperature and moisture content

Humphreyt, Philip E.; Ren, Shan

doi:10.1163/156856189x00290

Cited by 18 publications

(10 citation statements)

References 12 publications

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“…The activation energies calculated at 41%, 75% and 90% RH were 93, 99 and 98 k] mol-1, respectively. Note that little resin cure information at exposure times less 4 min was obtained for exposures at ~A is expressed in kg min-~ for flake bonding 263 110 ~ The activation energies observed in this study were very close to the value of 96 kJ mol-1 measured by Humphrey and Ren (1989) for the activation energy of bond strength development of a powdered PF resin. Since the activation energies measured here for the three relative humidities are close to each other, it indicates that the bonding relative humidity had little effect on the rate of resin bond strength development, especially between 75% and 90% RH.…”

Section: Bonding Kineticssupporting

confidence: 70%

“…To address this concern, a direct method to evaluate resin-wood bonding is required. Humphrey and Ren (1989) and Geimer et al (1990) separately developed techniques to follow the strength development of a resin-bonded joint under controlled isothermal and isohydro conditions. These studies showed that an optimum environmental condition exist for resin bonding.…”

Section: Introductionmentioning

confidence: 99%

“…These studies showed that an optimum environmental condition exist for resin bonding. Humphrey and Ren (1989) studied the effects of temperature and equilibrium moisture content (EMC) of wood on bond strength development of powdered PF resin between two wood disks. They observed that at 100 ~ or 115 ~ 10% EMC appeared to be optimal for the resin bonding, whereas a lower EMC (4%) significantly retarded resin bonding and a higher EMC (16%) caused relatively low bond strength by reducing the chemical reactivity of the resin.…”

Section: Introductionmentioning

confidence: 99%

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The effects of temperature and humidity on phenol-formaldehyde resin bonding

et al. 1995

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onSummary The effects of temperature and relative humidity on phenol-formaldehyde resin bonding were evaluated. Two flakes in a lap-shear configuration were bonded under an environment of controlled temperature (110 ~ 120 ~ 130 ~ 140 ~ and relative humidity (41%, 75%, 90%) for a series of time periods (0.25 to 16 min). The lap-shear specimens were then shear-tested on a mechanical testing machine and the results were used to establish a family of bond strength development curves at each temperature and level of relative humidity. At 1 I0 ~ the higher relative humidity appeared to retard resin bonding. The effects of relative humidity diminished as temperature increased to 140 ~ Bond strength development was chemical ratecontrolled. The rate of bond strength development at each relative humidity follows a first order reaction mechanism. The activation energy of resin-wood bonding, determined by bonding kinetics, was higher than that of resin alone, determined by differential scanning calorimetry. This comparison indicates that to form a strong resin-wood bond, a higher energy level might be required. 253

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Section: Bonding Kineticssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effects of temperature and humidity on phenol-formaldehyde resin bonding

et al. 1995

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“…Considerable movement of water in the vertical plane within any mattress is expected because of the role of water vapour in convective heat transfer. This complex three dimensional moisture content Variation is important because of the role of bound water in bond strength development Bolton 1979, Humphrey andRen 1989), and also in shrinkage and stress relaxation (Bolton etal 1989b). : Holzforschung 43 (1989) 265-274. be lost from near the platen, and successively gained and lost by layers closer to the central plane of the board.…”

Section: Predicted Variation Of Mattress Moisture Content and Relativmentioning

confidence: 99%

The Hot Pressing of Dry-formed Wood-based Composites. Part IV. Predicted Variation of Mattress Moisture Content with Time

Bolton¹,

Humphrey²,

Kavvouras³

1989

Holzforschung

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Using a thcorctical modcl, thc Variation of moisture contcnt and relative humidity within a particlcboard mattress during thc hot prcssing Operation is prcdictcd. Changc in thcsc variables with timc at a givcn Position in thc mattrcss, or with position in cithcr a vcrtical or a horizontal plane at a givcn timc, can rcadily bc studicd. Thc cffcct of a numbcr of proccssing variables on moisture contcnt Variation is analyscd, with thc prcdictions of thc modcl bcing comparcd with thc limitcd cxpcrimcntal data availablc. Thc prcdictcd data agrce rcasonably well with thosc obscrvcd cxpcrimentally.

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“…Although some good theoretical studies which shed some light on the bevaviour at the molecular level of the wood/aminoplastic interface already exist (Pizzi 1990 a, b), the rheological behaviour of the interface is not well-known. Even lower is the extent of knowledge in the process of hardening of these adhesives in a wood joint, although some notable starts have already been undertaken (Bolton and Humphrey 1977;Geimer 1990;Humphrey and Bolton 1979;Humphrey and Ren 1989;Humphrey and Zavala 1989). It is with this in mind that the research work presented in this article deals with the evolution of the physical properties of these adhesives during their hardening process in the presence of wood, hence in situ by the technique of thermomechanical analysis (TMA).…”

Section: Introductionmentioning

confidence: 99%

Thermomechanical Analysis of Wood/Aminoplastic Adhesives Joints Cross-Linking - UF, MUF, PMUF

Yin¹,

Deglise²,

Masson³

1995

HFSG

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Non-isothermal and isothermal thermomechanical analysis (TMA) of the cross-linking and hardening of wood joints bonded with urea-formaldehyde (UF), melamine-urea-formaldehyde (MUF), and phenol-melamine-urea-formaldehyde (PMUF) resins was carried out, allowing the determination of the variation of physical properties of these thermosetting adhesives in situ in the wood joint. Gelling temperature, hardening and vitrification temperature and temperature at which relative elastic moduli reach their maximum were also determined for wood joints obtained with the three resins. Deductions as regards rates of hardening, influence of amount of hardener and of curing temperature are reported on the basis of the measured TMA variation of the relative elastic moduli of the joints assemblies.

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Bonding kinetics of thermosetting adhesive systems used in wood-based composites: the combined effect of temperature and moisture content

Cited by 18 publications

References 12 publications

The effects of temperature and humidity on phenol-formaldehyde resin bonding

The effects of temperature and humidity on phenol-formaldehyde resin bonding

The Hot Pressing of Dry-formed Wood-based Composites. Part IV. Predicted Variation of Mattress Moisture Content with Time

Thermomechanical Analysis of Wood/Aminoplastic Adhesives Joints Cross-Linking - UF, MUF, PMUF

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