4.2. Flexural properties
Fig. 2, enumerates the flexural properties of PHBV, and it composites
in various proportion of talc and wood fiber. Trends of flexural
strength and modulus are moderately identical to those of
tensile. A leap of 270% in modulus and 22% in strength was observed
with the 40 wt.% talc in PHBV. Modulus of the hybrid composites
plummeted, while replacing the talc with wood fiber by
10 wt.% in each subsequent step. There was no difference in
strength and modulus between the final two compositions (10/
30/60 wt.% talc/wood fiber/PHBV and 40/60 wt.% wood fiber/
PHBV) of composites. The modulus and strength of the composition
at 20 wt.% of talc and 20 wt.% wood fiber was higher by
200% and 8%, respectively from that of neat PHBV and by 17%
and 8% from that of 40 wt.% wood fiber in PHBV. Meager difference
in the trends of flexural properties to that of tensile was due to different
directional stresses induced to the specimen during the testing.
During the tensile testing the specimen was induced to the
uniaxial tensile stress while in the flexural testing the specimen
was induced to uniaxial compression as well as tensile stress acting
simultaneously in the opposite directions.