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Table 
shows some of the mechanical properties of MDF compared with other
wood and engineering products. As can be seen its values compare well
with other wood products. Table shows the physical
properties of the two board types used in this study.
Table: A summary of the technical data as provided by the
manufacturer
There have been few studies of the effect of moisture content on the
mechanical properties of MDF. However, one study in the area was
undertaken by Watkinson, (1990). This study examined the mechanical
properties of one type of MDF, composed of radiata pine (Pinus
radiata D. Don ) and urea
formaldehyde resin, over a
range of humidities. The results are
summarised in Table . 
.
Watkinson (1990) found an increase in MC and TS, and decreases in MOE,
MOR and IB with increases in RH. No explanations were given for the
observed changes in mechanical properties with increasing
RH. Explanations are however available for solid wood as follows; almost all
strength properties of solid wood increase with decreasing MC, due to
the fact that as moisture is removed, shrinkage occurs that draws the structural
units more closely together, thus materially increasing the extent of
secondary valence hydrogen bonding between cellulose chains [Stamm, 1964]. The
action of moisture on urea formaldehyde, one of the constituents of
one of the
MDF types used in this study, is detrimental to the mechanical
properties of boards (Section ).
Table: Summary of the results of an earlier study on the effects of
humidity on the moisture sorption and mechanical properties of MDF