CONCLUSIONS
Traditional pulp-molded products, such as egg cartons, are typically
of low density and function primarily as cushioning for
packaging. At the Forest Products Laboratory, the development
of Spaceboard process technology has been an attempt to produce
highly densified, three-dimensional structures from paper
pulp. One of these structures is a GRIDCORETM panel. The
hex mold configuration and process conditions used result in
panel facings with specific gravities near 1. At these densities,
significant internal bond strength is developed and mechanical
properties suitable for structural applications can be achieved.
For example, from bending tests at 50% RH, calculate MOE
values ranged from 5 GPa for 100% OCC panels to 6 GPa for
100% kenaf panels. The MOR values range from 20 to 35 MPa
for the same respective panels. These values are very near reported
values for high density hardboard and above the geometric
mean for high strength papers. Sheathing grade plywood,
however, has about twice this strength. However, Spaceboard
has less than one-half the basis weight of an equivalent
thickness of plywood.
One of the most desirable features of the Spaceboard forming
process, in terms of recycling, is the ability to tolerate “contaminated”
fiber sources. The kenaf pulp used in this study had
a rather high shive content (24%). This shive content is unacceptable
for making paper but works well in Spaceboard.
Therefore, pulps made from agricultural fiber sources such as
kenaf need not be reduced to single fibers, reducing both the
energy required to produce pulp and damage to fiber integrity.
The ONP used in this study was not deinked. Drainage rates are
an important aspect of the Spaceboard process and are affected
by contaminate level and mold design. Provisions can be made
to circumvent these problems.
Although our results show that the mechanical properties of
Spaceboard may be suitable for structural applications, there
are other significant issues that must be addressed before it can
be used in these applications. Of utmost concern is the issue of
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durability. To meet code requirements, sheathing panels must
pass a wet/redry cycle. Therefore, wet strength and stiffness
must be imparted to the panels. Other concerns are fire resistance,
pest and fungal resistance, and fastening requirements.
These areas are the focus of continued research under CRADA
activities with GSI.