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The mechanical properties of the vinyl ester reinforced with oil palm of empty fruit bunch fibers (EFB) laminated at different layer arrangements with glass fiber (CSM) composites were investigated. The EFB and CSM fibers were laminated at different layer arrangements and then were impregnated with vinyl ester resin using resin transfer molding (RTM). Post-cure was carried out after cool press for about 24 h in an oven at 508C. Six different layers of lamination with a ratio of 50/50 fiber composite (50% EFB and 50% CSM) were manufactured. Control fiber composites with 100% mechanical fibers, 100% chemical fibers and 100% glass fibers were investigated for comparison. The mechanical properties (tensile, flexural, and impact test) and physical properties (water absorption, dimension stability, and density) were analyzed. The mechanical properties, water absorption, and density of hybrid composites exhibited higher properties than control composites (chemical and mechanical fibers). While comparing the layers of orientation of hybrid composites, the results of the tensile and flexural tests showed that composites with glass fiber at the outer layer showed higher tensile and flexural properties than the others.The impact test and the composites with natural fibers in the outer layer showed the highest results as compared to other layer laminations. However, hybrid composites exhibited comparable properties as compared to glass fiber composites, alone.KEY WORDS: vinyl ester, empty fruit bunch (EFB), glass fibers, mechanical and physical properties, water absorption, dimension stability, thermoset composites.

In this study, 25-year-old oil palm biomass (OPB) fiber-polypropylene (PP) composites are prepared by five different fiber loadings (10, 20, 30, 40, and 50%). The types of OPB used are oil palm empty fruit bunches, oil palm frond, and oil palm trunk. Transmission electron microscopy has confirmed that the cell wall structures of the various oil palm fibers have different cell wall thicknesses and exhibit the same ultrastructure as that of wood. The fibers consist of middle lamella, primary, and thick secondary walls with different thicknesses for different types of fibers. The secondary wall is differentiated into a S 1 layer, a unique multi-lamellae S 2 layer, and a S 3 layer. OPB fibers are compounded with PP using a Brabender DSK 42/7 twin screw extruder. The mechanical features such as tensile, flexural and impact properties of the OPB-PP composite are studied. The melt flow index (MFI) of the composite materials is also studied. Generally, the results show that lower fiber loading (10%) exhibits the highest tensile strength and MFI properties as compared to higher fiber loading (50%). Evidence of a fiber-matrix interphase is analyzed using scanning electron microscopy.

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Soil burial tests were carried out to evaluate the effect of biodegradation on the mechanical properties (tensile, flexural, and impact) and the mass loss of OPT fiber-filled RPP composites, as compared to control samples (virgin PP and RPP without filler). The composite samples were prepared using 30% w/w of OPT filler with a size of 100 mm. Compounding was carried out using a Haake Rheodrive 500 twin-screw compounder operating at 1908C and 8 MPa for 30 min. The effect of biodegradation was performed in a perspex plastic apparatus for 12 months. Assessments of the mechanical properties and the percentage of mass loss were carried out at 3, 6, and 12 months of exposure in soil. The mechanical properties (tensile, flexural, and impact) of materials deteriorate with an increase in exposure time. The effects of biodegradation increase with burial period, i.e., from 0 to 12 months. The tensile properties, flexural properties, and impact strength of the composites decrease by about 38-47%, 37-50%, and 47%, respectively, as compared to the value before the biological test.