Effect of Hybrid Castor Nutshell/Pineapple Leaf Fiber Loading on Creep Behavior of Epoxy Composites

Abstract

Epoxy composites can undergo time-dependent deformation under sustained loading, limiting their dimensional stability, while agricultural residues offer potential as sustainable reinforcements. This study evaluated the effect of hybrid castor nutshell (CNS) and pineapple leaf fiber (PALF) powder loading on the displacement response and fracture-surface morphology of epoxy composites. CNS and PALF powders (75 µm) were combined at a 50:50 weight ratio and incorporated at total loadings of 0, 5, 10, 15 and 20wt%. The composites were fabricated by hand lay-up and evaluated using dynamic mechanical analysis (DMA)in three-point-bending mode at 100°C; scanning electron microscopy (SEM) was used to examine the tested specimens. The neat epoxy reached a displacement of approximately −103µm. The reinforced formulations showed loading-dependent responses, with reported later-stage displacements of approximately −63, −78 and −65µm for the 10, 15 and 20wt% composites, respectively; the 5wt% specimen showed a distinct change to approximately +12µm. SEM indicated the most homogeneous dispersion and lowest measured void and agglomerated areas in the 5wt% composite, whereas the 15wt% composite showed the greatest agglomeration and void content. These results indicate that hybrid CNS/PALF loading and dispersion influence the measured deformation response. However, because the study reports displacement rather than a normalized creep strain or compliance, and is limited to one temperature and a short test, further standardized creep testing is needed before drawing conclusions about long-term performance.