There are several levels of learning. The first level is our observations of some phenomenon. We may not understand what is going on but it has started our process of leaning. The next level is the accumulation of facts and data as we start to study the phenomenon we first observed. Finally, we start to understand what we have observed and studied. Even at the understanding level, there are three levels: the macro level, micro level and molecular level. The macro level is an understanding of what we observed, the micro is to understand the data from the tests we have conducted, and the final level of understanding is what is really going at the molecular level.
We can study the properties and performance of wood at all of these levels of learning and understanding. Table 1 shows the properties and performance of wood. Wood is hygroscopic and takes on moisture resulting in changes in dimensions; increasing in volume as moisture is sorbed and shrinks as moisture is lost. Because wood is an organic resource, it is attacked by a wide variety of micro and macro organisms. Wood is also degraded by ultraviolet radiation resulting in color changes and surface erosion. Wood is also degraded at high temperatures due to the production of volatile gasses and char at high temperatures. Finally, the strength of wood depends on the properties of the cell wall matrix.
Keywords: Degradation, Cell wall, Moisture
Authors
Rowell R.
University of Wisconsin, Madison, WI
Login to download the PDF