It was known that the variability of either compressive or tensile
strength depended on the foam morphologies, especially of
cell walls. Although the porous cell structure was observed in
latex foam as shown in Fig. 3(a), the cells were continuous and
most starch and CaCO3 particles were deposited around the fiber
areas as exhibited in Fig. 3(b). This observation was not surprising
because the superior compatibility between aspen fibers and
rubber molecules appeared to promote latex coating as well as
the distribution of introduced starch and CaCO3 particles in the
batter. During baking process, the presence of wood fiber slowed
the water evaporation and achieved foam with good cell structures
behaved as a thickener. Moreover, the embedded fibers also
helped the latex matrix form porous structures during baked foaming
process, unlike gelatinized porous foamed starch. Due to fiber
presented, latex foams had improved mechanical properties.