Chemistry Reference
In-Depth Information
Figure 6.5 The effect of water and fibers on the DSC (differential scanning calor-
imetry) behavior of bio-based PU spray foams.
Reproduced from ref. 6 with permission from the authors.
that both wood fiber and microclay could improve foam tensile and
compressive strengths with the increase of isocyanate index from 110 to 250
(ref. 3). Moreover, wood fiber has better reinforcement properties than
microclay with higher isocyanate indexes, as shown in Figure 6.6(b) and (c).
Therefore, wood fiber is a better reactive bio-mass in PU foam manu-
facturing than microclay, when considering increasing environmental
concerns and economic considerations.
With the demands of decreasing carbon footprints, bio-mass materials are
attracting interest in PU foam manufacturing, typically for building PU insu-
lation. Gu and co-workers have done lots of work on wood-fiber-reinforced PU
spray foam composites with the potential for use in building and construction
applications.
4,6,7
With the exposure of hydroxyl groups on the fiber surface, the
existence of wood fiber increased the foam density and the cell size
4,7
(Figure 6.7) but decreased the foam tensile strength at low isocyanate
index.
3,4
The tensile strength of the PU spray foam decreased, while the com-
pressive strength increased, as the fiber amount increased (Figure 6.8). Wood
