Journal of Materials Science

, Volume 54, Issue 1, pp 705–718 | Cite as

X-ray methods to observe and quantify adhesive penetration into wood

  • Joseph E. Jakes
  • Charles R. Frihart
  • Christopher G. Hunt
  • Daniel J. Yelle
  • Nayomi Z. Plaza
  • Linda Lorenz
  • Warren Grigsby
  • Daniel J. Ching
  • Fred Kamke
  • Sophie-Charlotte Gleber
  • Stefan Vogt
  • Xianghui Xiao
Materials for life sciences


To accelerate development of new and improved wood adhesives for engineered wood products, the optimal adhesive penetration into wood needs to be better understood for specific products and applications. Adhesive penetration includes both flow of adhesives into wood micron-scale voids and infiltration into the polymer components of the wood cell wall layers. In this work, X-ray computed tomography (XCT) and X-ray fluorescence microscopy (XFM) were used to study adhesive flow and infiltration. Model wood–adhesive bondlines were made using loblolly pine (Pinus taeda) latewood substrates and bromine-substituted phenol formaldehyde (BrPF) resins with different weight-average molecular weights (MW). The Br substitution facilitated both qualitative and quantitative observations using XCT and XFM. The BrPF resin flow into wood was visualized using XCT volume reconstructions and quantified by calculating the weighted penetration (WP). Examination of the shape of the cured BrPF–air interface in longitudinal tracheid lumina revealed that capillary action often played a role in BrPF flow. XFM mapping revealed the pathways of BrPF infiltration into the wood cell walls, and the results were used to calculate BrPF cell wall weight percent gain (WPGCW) in individual wood cell walls. Both WP and WPGCW decreased with increasing BrPF MW. Additionally, the middle lamella had higher WPGCW than its neighboring secondary cell walls, and within a given bondline the WPGCW decreased with increasing distance of the cell from the bondline. The results provide new insights that are needed in the development of improved models to understand and predict wood–adhesive bondline performance.



This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Compliance with the ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

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Copyright information

© This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection  2018

Authors and Affiliations

  1. 1.Forest Biopolymers Science and EngineeringForest Products Laboratory, USDA Forest ServiceMadisonUSA
  2. 2.ScionRotoruaNew Zealand
  3. 3.Wood Science and EngineeringOregon State UniversityCorvallisUSA
  4. 4.Advanced Photon SourceArgonne National LaboratoryLemontUSA

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