Effect of polyol on thermo-oxidative degradation of isocyanate resin for wood adhesives

Umemura, Kenji; Kawai, Shinya

doi:10.1007/bf00766234

Cited by 6 publications

(1 citation statement)

References 20 publications

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“…The mechanical properties of polyurethane adhesives are mainly determined by the prepolymer composition, but bonding performance is often influenced by additives and fillers [14]. Very critical in polyurethane modification is the coordination of isocyanate content and functionality [15]. Shear strength of bonded wood was increased by a higher number of hard segments in polyurethane.…”

Section: Introductionmentioning

confidence: 99%

Modifying elastic modulus of two-component polyurethane adhesive for structural hardwood bonding

Bockel

Harling²,

Konnerth

et al. 2020

J Wood Sci

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Subject to this study is the modification of an experimental two-component polyurethane (2C PUR) as an alternative adhesive for structural hardwood bonding. The 2C PUR has been adapted by calcium carbonate as filler to increase its modulus of elasticity with the aim of increasing the modulus analogue to the ones typically observed for classic amino- and phenol based adhesives. The 2C PUR system was compared with a commercial one-component polyurethane (1C PUR) and a phenol resorcinol formaldehyde (PRF) adhesive. The wetting properties of the adhesives were tested in terms of surface tension, polar and dispersive part and contact angle on European beech wood (Fagus sylvatica L.). In addition, adhesive polymer films of 2C PUR were tested for tensile strength and modulus of elasticity (E-Modulus) following ISO 527-1. The adhesives bond performance on beech wood was determined by lap-joints according to EN 302-1 in various climate conditions. The results show that 2C PUR has proper wettability properties on beech wood. Adding 60% wt filler to the polyol component increased the E-Modulus from 2.3 GPa (0%) to 4.4 GPa. The tensile strength of the modified 2C PUR polymer films was comparable with the industrial 1C PUR. Tensile shear strength and wood failure percentage of 2C PUR lap-joints were increased by adding filler and met requirements in dry and re-dried conditions according to EN 302-1. However, the addition of filler didn’t result in an improvement in wet conditions. The present study shows sufficient performance for bonding hardwood with 2C PUR in dry conditions, while the system still needs to be improvement regarding its performance in humid conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Modifying elastic modulus of two-component polyurethane adhesive for structural hardwood bonding

Bockel

Harling²,

Konnerth

et al. 2020

J Wood Sci

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show abstract

Durability of isocyanate resin adhesives for wood III: degradation under constant dry heating

Umemura

Kawai

2002

J Wood Sci

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Durability of isocyanate resin adhesives for wood IV: degradation under constant steam heating

2002

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The durability of isocyanate resins consisting of emulsion-type polymeric diphenylmethane diisocyanate (EMDI) was investigated under constant steam heating. Two kinds of resin, water only-added resin and polyol/ water-added resin, were used in this study. The degradation of the resins under steam heating was observed using Fourier transform infrared spectroscopy (FT-IR), weight changes, and thermogravimetric analysis (TGA). FT-IR analysis showed that the degradation reaction of the resins scarcely proceeded for a few hours and then increased significantly. The weights of the resins decreased linearly during steam heating. The thermal stability of steamtreated resins was made clear by TGA. The bond strength reductions of the specimens bonded with the resins were also observed. The best fitting regression function for the behavior of bond strength reduction was determined statistically. The apparent activation energy of each resin was calculated from the regression function, for the half-life period. Considering the calculated values, the adhesion durability of using polyol-added resin was superior to that of using water only-added resin. It was clarified that the durability of the isocyanate resins under steam heating was markedly inferior to that under dry heating.

show abstract

Effect of polyol on thermo-oxidative degradation of isocyanate resin for wood adhesives

Cited by 6 publications

References 20 publications

Modifying elastic modulus of two-component polyurethane adhesive for structural hardwood bonding

Modifying elastic modulus of two-component polyurethane adhesive for structural hardwood bonding

Durability of isocyanate resin adhesives for wood III: degradation under constant dry heating

Durability of isocyanate resin adhesives for wood IV: degradation under constant steam heating

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