Probing the nanostructural mechanisms behind decay resistance of chemically modified wood using small angle neutron scattering

Abstract

While it is known that modifying the hydroxyls in wood can improve the decay resistance; what is often missing in the literature is whether these modifications alter wood nanostructure, and how these changes correlate to the improved decay resistance. Here, we used SANS to probe the effects of alkylene oxide modification on wood nanostructure. Southern pine wood samples were chemically modified to various weight percentage gains (WPG) using four different alkylene oxides: propylene oxide (PO), butylene oxide (BO), epichlorohydrin (EpH) and epoxybutene (EpB). After modification, the samples were water leached for two weeks to remove any unreacted reagents. Then, we conducted laboratory soil block decay evaluations against the brown rot fungus Gloeophyllum trabeum to determine weight loss and biological efficacy of the modifications. To assist in understanding the mechanism, we used SANS to study samples that were fully immersed in D₂O. These measurements revealed that the modifications altered the water distribution inside the cell wall, and the most effective modifications reduced the microfibril swelling. Likewise, we observed that these modifications were also able to preserve the microfibril structure even after being subject to 12 weeks of brown-rot decay.

Citation

Plaza, N.Z.; Ibach, R.E.; Pingali, S.V. 2021. Probing the nanostructural mechanisms behind decay resistance of chemically modified wood using small angle neutron scattering. In: 2021 International conference of the Forest Products Society. June 15-17, 2021. Virtual. LaGrange, GA: Forest Products Society: 159-163.