Jute and banana fibers are biodegradable green fibers being increasingly used to replace synthetic fibers in fiber-reinforced polymer composites. Integration of jute and banana distinct natural fibers has the potential to improve composite performance in secondary structural applications. In this study, an equal quantity of unidirectional jute and banana fibers with four different fiber orientations [(0/0) 3s , (0/45) 3s , (0/90) 3s , and (+45/À45) 3s ] was embedded in phenol formaldehyde resin to make hybrid laminates using the hot press method. Tensile, flexural, impact, interlaminar shear strength (ILSS), and single-end notch bend tests are performed in accordance with the ASTM standards to evaluate the effect of fiber orientation on natural fiber hybrid composites (NFHCs).Experimental results revealed that changing the fiber orientations [(0/0) 3s ] leads to a major impact on reducing the mechanical properties of NFHC laminates to the extent of 39%. Furthermore, the tensile strength, Young's modulus, impact and ILSSs, and fracture toughness were found to be 37% higher for the (0 /0 ) 3s composite. Additionally, tensile, flexural, and impact fractured specimens were examined by scanning electron microscopy to understand the fiber-matrix failure behavior due to inter-ply orientation in NFHCs.

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The primary purpose of this study is to realize quantitative fiber loading effects on free vibration, damping behavior, fracture toughness, thermal conductivity, inter-laminar shear strength, and flammability of jute-banana fiber phenolformaldehyde (PF) hybrid composites. These composites were manufactured with fiber weight percentages ranging from 30% to 60% using hot press technique. Hybrid composite with equal amount of fiber and resin (PJB-2) had a higher natural frequency in the range of 4.8%-59%, a higher inter-laminar shear strength varying from 30% to 54%, a higher fracture toughness with minimum of 19 to maximum of 44%, and a low damping factor in the range of 25%-59% to that of other composite having unequal amount of fiber and resin loading. In contrast to other composites, the composite containing 30 wt% fiber (PJB-4) has a high heat conductivity of about 10%-20%. However, the thermal conductivity of jute-banana fiber PF composites declined as the fiber content increased beyond 30 wt%, while the flame resistance was improved as the resin concentration increased. Additionally, Scanning electron microscopy (SEM) studies clearly indicates the failure patterns of fiber matrix interface under Inter laminar shear strength and fracture toughness tests were supports to justify the experimental results.

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Laminates of L-bends are inherently weak in the through thickness direction at the region of curvature. To address this behavior, experimental investigations have been made to find the influence of graphene oxide (GO) and Kenaf short fibres on interlaminar radial stress of a unidirectional glass epoxy L-bend composite laminate. Kenaf in the range of 5-10 wt% and GO in the range of 1-2 wt% were loaded at each ply at the curvature of a L-bend and their influence on curved beam strength (CBS) was investigated experimentally as per ASTM D6415. L-bend composite specimens with and without fillers were fabricated with the aid of hand lamination technique. Four point bending fixtures were designed and fabricated to hold the specimen firmly in the uniaxial tension machine. Tests were carried out as per ASTM D6415 and load displacement plots were carefully recorded. Experimental data revealed that the laminate loaded with Kenaf fibres at the curvature radius of L-bend had greater influence on CBS and interlaminar stresses than GO. Further, the delaminated surfaces of L-bend at the curvature region was carefully examined using scanning electron microscope to know the interfacial adhesion mechanism of Kenaf and GO with epoxy and glass fibre.

Laminates of fibre-reinforced prepreg have excellent in-plane mechanical properties, but have inadequate performance in the through thickness direction. Here, we address this issue by application of epoxy-terminated butadiene nitrile (ETBN) liquid rubber between the prepreg laminae using an automatic draw bar coating technique. Test results reveal that by adding ETBN in small quantities in the range of 9.33–61.33 g/m2, the interlaminar critical energy release rates (GIc and GIIc) are improved by up to 122% in mode-I and 49% in mode-II. Moreover, this finding is further supported by the dynamic mechanical analysis thermograms that clearly indicate that coating has not altered the Tg of ETBN-coated samples. Scanning electron microscopic analysis of fracture surfaces showed that rubber particles formed micro cavitations in the epoxy, causing localised rubber rich regions. These resin-rich regions require more energy to fracture, resulting in increased toughness of the glass epoxy prepreg systems.