Characterization of henequen fibers and the henequen fiber/poly(hydroxybutyrate-co-hydroxyvalerate) interface

The henequen fiber/poly(hydroxybutyrate-co-hydroxyvalerate) resin (PHBV) interfacial shear strength was characterized by single-fiber fragmentation (SFF) (also called the single-fiber composite test) and microbond techniques. The surface microstructure and tensile properties of henequen fibers were characterized using a scanning electron microscope (SEM) and an Instron tensile testing machine. The moisture content of the fibers was measured using a Brabender rapid moisture/volatile tester. SEM photomicrographs of the longitudinal views of the henequen fibers showed their fibrillar structure and the transverse views showed their hollow/multicellular nature and noncircular cross-section. The henequen fiber/PHBV interfacial shear strength was 6.97 MPa, as measured using the SFF test, and 5.24 MPa, as measured using the microbond test. These results are surprisingly close in spite of the different stresses experienced during the SFF and microbond tests. SEM photomicrographs showed interfacial failure. The interfacial shear strength was attributed mainly to the mechanical interlocking resulting from the fiber surface roughness, since no hydrogenbonding possibility existed for PHBV.The fiber/resin mechanical interlocking, however, may also be limited because of the high viscosity of the resin, which limits its ability to penetrate into and around the cells.