The development of natural fiber-based composite materials is an
attractive alternative to replace synthetic materials due to its
lightweight, strong, and environmentally friendly properties. This
study aims to determine the effect of the combination of sugar palm
fiber and pineapple leaf fiber on the bending strength and
macrostructure of polyester resin matrix composites. The fibers used
were derived from natural waste, each cut to 150 mm in length and
combined with Yucalac 157 BQTN-EX polyester resin and MEKPO
catalyst. The specimen manufacturing process used the hand lay-up
press method, while the flexural strength testing was carried out
based on the ASTM D-790 standard. The macrostructure was
observed using a macro lens to see the fiber distribution, voids, and
delamination. This study used five variations of specimen
composition, namely: specimen 1 (40% palm fiber, 59% resin, 1%
catalyst), specimen 2 (40% pineapple fiber, 59% resin, 1% catalyst),
specimen 3 (20% palm fiber, 20% pineapple fiber, 59% resin, 1%
catalyst), specimen 4 (15% palm fiber, 25% pineapple fiber, 59%
resin, 1% catalyst), and specimen 5 (25% palm fiber, 15% pineapple
fiber, 59% resin, 1% catalyst). The results showed that variations in
fiber composition affected the flexural strength and macrostructure
of the specimens. The combination with pineapple fiber dominance
in specimen 5 produced the highest bending strength of 80 MPa,
while the specimen with sugar palm fiber dominance in specimen 3
only reached 59.4 MPa. The even fiber distribution, strong
interphase bonding, and minimal voids contributed significantly to
the improvement in mechanical performance. This study shows that
natural fibers have great potential in the manufacture of high-quality
composites.