Fracture cleavage analysis of PVAc latex adhesives: Influence of phenolic additives
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Francisco López-Suevos
Abstract
Mode I fracture cleavage testing was conducted on wood bonded with poly(vinyl acetate-co-NMA) latex adhesive containing two types/degrees of cross-linking: (1) cross-linking through AlCl3 catalysis of N-methylolacrylamide (NMA) comonomer; and (2) additional cross-linking using a phenol-formaldehyde resol additive, in addition to AlCl3 catalysis. The formulation lacking the phenolic additive performed well under dry conditions; but it completely failed during testing as a result of accelerated weathering. In contrast, fortification with the phenolic additive provided durability against accelerated weathering. In an effort to understand the effects of accelerated weathering, parallel-plate dynamic mechanical analysis was applied to freestanding neat adhesive films and to wood-bonded films (composites). Accelerated weathering dramatically altered the viscoelastic response of films and composites that lacked the phenolic additive; weathering caused a second, broad and reversible relaxation near 100°C, which might be because of softening of the poly(vinyl alcohol) interfacial agent used during emulsion polymerization. In contrast, samples formulated with the phenolic additive only displayed the typical base-polymer glass transition. Correlation of the fracture testing and the rheological analysis suggests that the phenolic additive promotes adhesive durability by cross-linking the interparticle boundaries, where poly(vinyl alcohol) is believed to reside.
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©2006 by Walter de Gruyter Berlin New York
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- Brightness stabilisation of bleached high-yield pulps by novel sulfur-containing inhibitors
- Application of UV-Vis and resonance Raman spectroscopy to study bleaching and photoyellowing of thermomechanical pulps
- Characteristics of NAEM salt-catalyzed alcohol organosolv pulping as a biorefinery
- Effect of poly(ethylene oxide) molecular mass on miscibility and hydrogen bonding with lignin
- Calculation of the relative bonded area and scattering coefficient from sheet density and fibre shape
- Formic and acetic acids in archaeological wood. A comparison between the Vasa Warship, the Bremen Cog, the Oberländer Boat and the Danish Viking Ships
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- Air permeability of aspen veneer and glueline: Experimentation and implications
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