You are here: Home
/ Publication Information
Title: Failure mechanisms in wood joints bonded with urea-formaldehyde adhesives
Author: River, B.H.; Ebewele, R.O.; Myers, G.E.;
Source: Holz als Roh- und Werkstoff. Vol. 52 (1994): Pages 179-184
Publication Series: Miscellaneous Publication
Description: Wood joints bonded with urea-formaldehyde (UF) are weakened by cyclic swelling and shrinking. To study the failure mechanisms in UF-bonded joints, specimens were bonded with unmodified, modified (amine), or phenol formaldehyde adhesive and subjected to accelerated aging. Modification of the adhesive properties increased the cleavage fracture toughness and shear strength of bonded joints and improved the resistance of joints to cyclic swell-shrink treatment and accelerated moist-heat aging. Joints bonded with some modified urea-formaldehyde adhesives were as resistant to these treatments as joints bonded with phenol formaldehyde. Physical and mechanical origins of the improved adhesive performance were determined by microscopic analysis. Cure-shrinkage stresses precracked unmodified adhesive layers and damaged the wood interphase. The damaged interphase was especially susceptible to the effects of cyclic swelling and shrinking stresses. Certain modifiers reduced or eliminated cure-shrinkage cracking and damage to the wood. Moist-heat aging caused molecular scission in the bulk unmodified adhesive layer as revealed by the onset of shear cracking in the adhesive layer and erosion of exposed surfaces. Certain modifiers reduced or eliminated molecular scission and erosion responsible for adhesive weakening in moist-heat aging. We conclude that incorporating flexible amines in the adhesive structure improves the durability and stability of UF-bonded joints.
Keywords: Wood joints, wood adhesives, urea-formaldehyde adhesives, failure
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
XML: View XML
River, B.H.; Ebewele, R.O.; Myers, G.E. 1994. Failure mechanisms in wood joints bonded with urea-formaldehyde adhesives. Holz als Roh- und Werkstoff. Vol. 52 (1994): Pages 179-184
Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility