Accessibility of hydroxyl groups in furfurylated wood at different weight percent gains and during Rhodonia placenta decay

Greeley Beck,Gry Alfredsen,Pierre Martin Cocher,Callum Hill

doi:10.1007/s00107-019-01445-4

Abstract

Deuterium exchange was used to measure accessible hydroxyl (OH) groups in furfurylated wood at different weigh percent gains (WPGs) and at different levels of mass loss caused by exposure to the brown-rot fungus Rhodonia placenta. The results from the deuterium exchange method showed that OH accessibility in furfurylated samples did not change with increasing WPGs. However, OH accessibility in furfurylated samples increased significantly after initiation of decay at commercial treatment level (mean WPG 32%), which is attributed to degradation of crystalline cellulose regions and formation of new OH groups in lignin and the furfuryl alcohol polymer.

Highlights

Chemical wood modification imparts dimensional stability and decay resistance to the material
No statistically significant differences in hydroxyl group accessibility were found between the treatment levels nor compared to the radiata pine control
The lack of variation in OH content at different weigh percent gains (WPGs) levels and unmodified wood strongly suggests that there is no direct substitution of cell wall polymers and that retention of polymer in the cell wall is due to entanglement of the furfuryl polymers within the cell wall matrix

Summary

Introduction

Chemical wood modification imparts dimensional stability and decay resistance to the material. The volume occupied by the reagent in the cell wall reduces the cell wall moisture content below the optimum level for decay and, at the same time, holds the cell wall in a swollen state, imparting dimensional stability. The reaction of wood with furfuryl alcohol is classed as an impregnation modification because the reagent polymerises, to some extent, inside the cell wall. Furfuryl alchohol may react with the wood cell wall OH groups, this has yet to be definitively demonstrated. It is possible to determine whether the cell wall OH groups are involved in a reaction with a modifying agent by using deuterium exchange to determine accessible OH content. Deuterium exchange was used to determine reduction in OH content due to reaction with acetic anhydride (Popescu et al 2014). Beck et al (2017) showed that

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