The palm leaves used in the production of WPC have unidirectional loading
with thin and thick fibers that exist in the frond. The fibers extend from the fronds
to the leaves and form the main loading fibers. The swelling ratio and the tensile
strength of the three portions of the palm leaves namely; nodal, middle and rear
portion along with their average are calculated and plotted in Fig. 2. The swelling
is due to absorption of water which varies in the three portions of leaflet with
69.8% in near nodal portion followed by 60–64% in middle and rear portions of
the leaflet. The tensile strength of the leaf is between 41.8 and 50.7, with an average
of 45.3 MPa. Tensile strength near the nodal portion is slightly greater than middle
and rear portions, with an average of 45.33 MPa (see Fig. 2), which accounts for the
shrinkage of leaves as water content is lost and the increased ratio of fiber. Furthermore,
this variation may be due to more aggregation and distribution of fiber content
per unit area at nodal region.