Mat conditions of temperature and gas pressure were
measured in three locations for one conventional and four
steam-injection press schedules used in the laboratory scale
manufacture of aspen (Populus grandidentata and Populus
tremuloides) flakeboard. Two resins, phenol formaldehyde
and polymeric MDI, were used. Steam-injection press
schedules varied from low steam input to high steam input by
adjusting steam pressure, steam time, and the density range
for steam-injection during press closing. Steam-injection
rapidly raises mat core temperatures as compared to
conventional pressing. Temperature and gas pressure were
positively correlated with the amount of steam input.
Flakeboard strength and dimensional stability
properties were tested. Steam-injection pressing produced
panels with superior dimensional stability as compared to
conventional pressing. The high steam press schedule
produced internal bond and shear strengths equal to the
conventional press schedule for phenol formaldehyde. Medium
steam press schedules produced superior internal bond and
shear strengths to the conventional press schedule for
polymeric MDI. The conventional press schedule produced
superior static bending MOR strengths for both resins.
A fluorescence microscope was interfaced with a
digitizing image analysis system to measure resin
penetration area on flakes recovered from inside of the mat.
Wood anatomy was found to be the dominating factor in
creating high variablity in resin penetration area
measurements, as differences could not be detected due to
the press schedules or resin type.
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