Effects of Kenaf Fiber Orientation on Mechanical Properties and Fatigue Life of Glass/Kenaf Hybrid Composites

The objectives of this work were to investigate the effect of kenaf fiber alignment on the mechanical and fatigue properties of kenaf/glass hybrid sandwich composites. Three types of kenaf fibers were used, namely, non-woven random mat, unidirectional twisted yarn, and plain-woven kenaf. A symmetric sandwich configuration was constructed with glass as the shell and kenaf as the core with a constant kenaf/glass weight ratio of 30/70% and a volume fraction of 35%. Tensile, compression, flexural, and fully reversed fatigue tests were conducted, and a morphological study of the tensile failure surface of each hybrid composite was carried out. The non-woven mat kenaf hybrid had poor properties for all tests, while the unidirectional kenaf hybrid composite possessed higher tensile strength and similar compressive properties compared with the woven kenaf. Hybridization with kenaf fibers improved the fatigue degradation coefficient of the final composites to 6.2% and 6.4% for woven and unidirectional kenaf, respectively, compared with 7.9% for non-woven. Because woven kenaf hybrid composite is lightweight, environment friendly, and has a considerable balance in static and fatigue strengths with low fatigue sensitivity in bidirectional planes compared to glass, it is strongly recommended for structural applications

Partial Replacement of Glass Fiber by Woven Kenaf in Hybrid Composites and its Effect on Monotonic and Fatigue Properties

Natural–synthetic fiber hybrid composites offer a combination of high mechanical properties from the synthetic fibers and the advantages of renewable fibers to produce a material with highly specific and determined properties. In this study, plain-woven kenaf/glass reinforced unsaturated polyester (UP) hybrid composites were fabricated using the hand lay-up method with a cold hydraulic press in a sandwich-configuration laminate. The glass was used as a shell with kenaf as a core, with an approximate total fiber content of 40%. Three glass/kenaf weight ratios percentages of (70/30)% (H1), (55/45)% (H2), and (30/70)% (H3) were used to fabricate hybrid composites. Also pure glass/UP and kenaf/UP were fabricated for comparison purposes. Monotonic tests, namely tensile, compression, and flexural strengths of the composites, were performed. The morphological properties of tensile and compression failure of kenaf and hybrid composites were studied. In addition, uniaxial tensile fatigue life of hybrid composites were conducted and evaluated. The results revealed that the hybrid composite (H1) offered a good balance and the best static properties, but in tensile fatigue loading (H3) displayed low fatigue sensitivity when compared with the other hybrid composites

Effects of Processing Method, Moisture Content, and Resin System on Physical and Mechanical Properties of Woven Kenaf Plant Fiber Composites

Effects of the processing method, moisture content, and polymer type were evaluated relative to the physical and mechanical properties of composites based on natural plants. When kenaf was heated above the glass transition temperature of lignin, there was a reduction in moisture content by more than 8% of the total weight of the raw material. To investigate polymer behavior, the raw material was reinforced with three types of polymers: epoxy, unsaturated polyester (UP), and vinyl ester fabricated using hand lay-up with cold press (HCP) and vacuum infusion (VI). The results of (HCP) showed a noticeable improvement in tensile and flexural strength and their moduli for all types of polymer used compared with (VI), in ascending order from UP and vinyl ester to epoxy. Using the HCP method, the tensile strength improved considerably, by 60% for epoxy, 59% for UP, and 250% for vinyl ester, while flexural strength was enhanced by 16% for epoxy, 126% for UP, and 117% for vinyl ester compared to VI. Impact results showed a slight or no improvement in absorbed energy