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Informing the improvement of forest products durability using small angle neutron scattering

Author(s):

Sai Venkatesh Pingali
Shuo Qian
William T. Heller

Year:

2016

Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Forest Products Laboratory

Source:

Cellulose, Vol. 23(3). pp. 1593-1607

Description

A better understanding of how wood nanostructure swells with moisture is needed to accelerate the development of forest products with enhanced moisture durability. Despite its suitability to study nanostructures, small angle neutron scattering (SANS) remains an underutilized tool in forest products research. Nanoscale moisture-induced structural changes in intact and partially cut wood cell walls were investigated using SANS and a custom-built relative humidity (RH) chamber. SANS from intact wood sections cut from each primary wood orientation showed that although wood scattered anisotropically across 1.3–600 nm length scales, measurement of elementary fibril spacing and low-q surface scattering were independent of orientation. Water sorption caused spacing between elementary fibrils to increase with RH, and this swelling accounted for over half the transverse swelling in S2 secondary wood cell walls. Elementary fibril spacing in longitudinally cut wood cells, which were designed to mimic cells near woodadhesive bondlines, was greater than the spacing in intact cells above 90 % RH. This suggested that some cell wall hoop constraint from the S1 and S3 cell wall layers on the S2 layer was released by cutting the cells. Furthermore, increased spacing between elementary fibrils may also create diffusion channels that are hypothesized to be responsible for the onset of fungal decay in wood. Protocols were established to use SANS in future research to study adhesives and protection treatments to improve moisture durability in forest products.

Citation

Plaza, Nayomi Z.; Pingali, Sai Venkatesh; Qian, Shuo; Heller, William T.; Jakes, Joseph E. 2016. Informing the improvement of forest products durability using small angle neutron scattering. Cellulose. 23: 1593-1607.

Cited

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https://www.fs.usda.gov/treesearch/pubs/52916