| Summary: | Availability of raw material eichornia crassipesfiber in Indonesiais
relatively abundant, the potential of eichornia crassipes is very suitable for reinforcement of the materials. The particles of coconut coir (coco sponge), i.e. particles that cling to the coconu tfiber until now considered as waste material has been increased mainly from home industry in Kebumen. Research that will push the use of eichornia crassipes is considered very important to do. As aconsequence, for the primary structure, it also needs to study the characteristics of the mechanical properties of composite with core by coco sponge. Combining the mechanical properties of this optimization is apotential to be applied in composite sandwich structure in the future. The aims of the study is to determine the tensile, bending, impact properties of core by coco sponge, and composite reinforced by eichornia crassipes fiber, also composites and wich of a combination of these two materials.
The materials required in the manufacture of test specimens of eichornia crassipes fiber, coco sponge, urea formaldehit type UA-181, hardener HU-12, unsaturated polyester yukalac type 157 BQTN-EX, and catalyst MEXPO. Manufacturing of composite, core and sandwich made by press mold method. Specimens of composite, core and sandwich for bending test based on ASTMD-790, impact test specimens based on ASTMD-5942, and tensile test specimens based on ASTMD-638.
The results showed that the tensile strength, bending strength, and impact toughnessoptimumwere obtaind on the core by composition of 20% (fractionweight) coco spongeand 80%UF. The tensile strength, bending strength, and impact toughness of core are 3,54±0, 366MPa, 4,33±0, 366MPa, and 0,0043±0,00067J/mm2. Core with variations of thickness produce a linear value. The best result of composite in tensile and bending strength was composites by 20% (fractionvolume) fiber,i.e.
31,28±2,23MPa and 49,57±3,34MPa, while the bes timpact toughness was obtained incomposites by 40% (fractionvolume) fiberi.e. 0,011±0,0017J/mm2. Bending strength and impact toughness of composites and wich with core 5 mm in thickness of80% (fractionweight) UFandskincompositeby20%(fractionvolume)fiberi.e.
3,64±0,63MPaand0,007±0,001J/mm2. The best result of the composites and wichin bending strength by 20% (fractionvolume) fiber and 50% (fractionweight) coco sponge i.e.16,60±1,65MPa, while the best impact toughness was obtained incompositess and wich by 20% (fractionvolume) fiber as skin and 60% (fractionweight) coco sponge as core with 10mm in thickness i.e.0,00406±0,00029J/mm2.
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