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Forest Products Laboratory
One Gifford Pinchot Drive
Madison, WI 53726-2398
Phone: (608) 231-9200
Fax: (608) 231-9592
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An Innovative Method for Determining Moisture Gradient of Wood Products

X-ray radiation method to determine moisture gradient in wood. Forest Service
X-ray radiation method to determine moisture gradient in wood. Forest Service
Snapshot: Changes in moisture content of wood-based composite materials can lead to linear expansion and, more specifically, hygroexpansion. This can cause severe internal stresses resulting in deformities and defects such as warping, surface checks, and honeycomb during the wood drying process. A non-destructive method of measuring moisture content across a dimension of hygroexpansive composite material using radiation and volumetric shrinkage correction has been invented to create a profile of moisture content changes over time.
Summary:

Changes in moisture content of wood-based composite materials can lead to linear expansion and, more specifically, hygroexpansion. This can cause severe internal stresses resulting in deformities and defects such as warping, surface checks, and honeycomb during the wood drying process. A non-destructive method of measuring moisture content across a dimension of hygroexpansive composite material using radiation and volumetric shrinkage correction has been invented to create a profile of moisture content changes over time. The invention uses radiation to determine the depth and density of the composite material, which indicates the initial amount of moisture in the wood, and then uses volumetric shrinkage to provide a correlation of the density with a moisture content value. These measurements comprise the moisture content profile of the internal movement of moisture in hygroexpansive composite material. This profile can help researchers and manufacturers understand, control, and design a wood drying process that will reduce the occurrence of material deformities and defects. This innovation improves on previous methods for tracking changes in moisture content. Not only does it allow for continuous measurement, it also eliminates moisture loss due to testing procedures throughout the entire process. This potential on-line monitoring of moisture change in wood will help dry-kiln operators obtain optimal drying schedules and potentially improve productivity, efficiency, and energy consumption.
Princpal Investigator(s):
 Cai, Zhiyong

Fiscal Year: 2010
Highlight ID: 162
 
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