title: Synchrotron-based X-ray fluorescence microscopy in conjunction with nanoindentation to study molecular-scale interactions of phenol-formaldehyde in wood cell walls.
abstract: Understanding and controlling molecular-scale interactions between adhesives and wood polymers are critical to accelerate the development of improved adhesives for advanced wood-based materials. The submicrometer resolution of synchrotron-based X-ray fluorescence microscopy (XFM) was found capable of mapping and quantifying infiltration of Br-labeled phenol-formaldehyde (BrPF) into wood cell walls. Cell wall infiltration of five BrPF adhesives with different average molecular weights (MWs) was mapped. Nanoindentation on the same cell walls was performed to assess the effects of BrPF infiltration on cell wall hygromechanical properties. For the same amount of weight uptake, lower MW BrPF adhesives were found to be more effective at decreasing moisture-induced mechanical softening. This greater effectiveness of lower MW phenolic adhesives likely resulted from their ability to more intimately associate with water sorption sites in the wood polymers. Evidence also suggests that a BrPF interpenetrating polymer network (IPN) formed within the wood polymers, which might also decrease moisture sorption by mechanically restraining wood polymers during swelling.
authors.affiliation: †Forest Biopolymers Science and Engineering, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Jakes
authors.affiliation: †Forest Biopolymers Science and Engineering, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Hunt
authors.affiliation: †Forest Biopolymers Science and Engineering, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Yelle
authors.affiliation: †Forest Biopolymers Science and Engineering, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Linda
authors.initials: L
authors.lastname: Lorenz
authors.affiliation: ‡Analytical Chemistry and Microscopy, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Kolby
authors.initials: K
authors.lastname: Hirth
authors.affiliation: §X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Sophie-Charlotte
authors.initials: SC
authors.lastname: Gleber
authors.affiliation: §X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, United States.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vogt
authors.affiliation: ∥Scion, 49 Sala Street, Rotorua 3010, New Zealand.
authors.forename: Warren
authors.initials: W
authors.lastname: Grigsby
authors.affiliation: †Forest Biopolymers Science and Engineering, Forest Products Laboratory, U.S. Forest Service, One Gifford Pinchot Drive, Madison, Wisconsin 53726, United States.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Frihart
mesh_terms: D000269:Adhesives / Q000737:chemistry; D002473:Cell Wall / Q000737:chemistry*; D005557:Formaldehyde / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D019800:Phenol / Q000737:chemistry*; D017356:Synchrotrons; D014934:Wood / Q000737:chemistry*
chemical_list: D000269:Adhesives; D005557:Formaldehyde; D019800:Phenol
keywords: X-ray fluorescence microscopy; adhesive; infiltration; nanoindentation; wood