Failure Studies on Adhesive Bonded and Bolted Joints of Natural Fiber Composites

Composites with natural fibers as reinforcements are playing a vital role in recent developments. The present work deals with the fabrication of okra and empty fruit bunch banana fiber polyester matrix composites with varying reinforcement content (5%, 10%, and 15%). Composites were fabricated by using the hand layup technique. After the fabrication process, composites were then adhesively bonded and also joined with bolts. The main objective of this work is to analyse the failure studies on adhesive bonded and bolted joints of okra and empty fruit bunch banana composite specimens. The specimens were tested under tensile load, flexural creep studies, and SEM analysis. It has been observed that empty fruit bunch banana fiber composites exhibited better joint strength properties under tensile loading when compared to the okra fiber composites. To estimate the flexural creep behaviour, all the samples were tested at a constant load of 2.5kg and 5kg. The deflections obtained during regular time intervals (four months) were noted. The presence of internal defects and void content was observed by using the scanning electron microscope. The results showed that adhesive-bonded composites were exhibited less deflection compared to the bolted joints. The empty fruit banana fiber composites exhibited higher creep than okra fiber composites. Decreased creep with the increased fiber has been observed in both cases. SEM Adhesively bonded joints possessing better sustainability as compared to the bolted joints in both the fiber-reinforced composites.

Improvement of the Mechanical Properties of Hibiscus Esculentus (Okra) Fiber Reinforced Polymer Composite

Natural fiber and their composites are the emerging trends in material science. They are speedily gaining grounds in the replacement of synthetic reinforcements. This is due to their low density, high specific mechanical strength, ultimate availability and disposability and less processing requirements. Most plant based fibers have become centers of research. This work is based on Okra fiber. Okra fiber was used as reinforcement in vinyl ester polymer matrix. Okra fiber was chemically treated using NaOH to clean fiber surface, modify the surface to increase the surface roughness and in general enhance bond strength between fiber and matrix. Reinforcement of the matrix using Okra fiber increases mechanical properties of the composite. But for optimal result, certain parameters were considered and varied. The two parameters considered were: fiber length, and proportion or volume fraction. Different variations of fiber length considered were: 10mm, 30mm and 50mm while the different fiber volume fractions considered are 10%, 30% and 50%. This work has analyzed how these parameters can be best combined for optimum values of tensile properties of the composite. The tensile strength of composite was highest at fiber length of 50mm and volume fraction of 10% at ultimate tensile strength of 214MPa.

Comparative Study of Jute, Okra and Pineapple Leaf Fiber Reinforced Polypropylene Based Composite

In this experimental studies, three types of fabric such as Jute, Okra and Pineapple Leaf Fiber (PALF) were selected and matrix material such as polypropylene (PP) was selected to manufacture composites. Jute/PP, Okra/PP, and PALF/PP based composites were prepared successfully by a conventional compression molding technique. The objective of this study is to compare the mechanical such as tensile strength (TS), tensile modulus (TM), bending strength (BS), bending modulus (BM), elongation at break (Eb%) and interfacial properties of the composites. Jute fiber (hessian cloth)-reinforced polypropylene matrix composites (45wt% fiber) were fabricated by compression molding. TS, TM, BS, BM, and IS of the composites were found to be 45 MPa, 2.2 GPa, 54 MPa, 4.1 GPa, and 16 kJ/m2, respectively. Then Okra and PALF fiber reinforced polypropylene-based composites (45 wt% fiber) were fabricated and the mechanical properties were compared with those of the jute-based composites. The result revealed that mechanical properties of PALF composite higher than jute and Okra fiber reinforced composites. Water absorption and elongation percentage at break showed different scenario and it was noticed from the experimental study that water absorption and elongation at break (%) of jute fabric was higher than other composites. Fracture sides of the composites were studied by scanning electron microscope (SEM), and the results revealed poor fiber-matrix adhesion for jute fiber-based composites compared to that of the other fiber-based composites (OF/PP and PALF/PP). KEY WORDS: Polypropylene, Jute Fiber, Okra Fiber, Pineapple Fiber, Mechanical Properties, Interfacial Properties, Composites. *Corresponding Address: [email protected]

Fabrication, Mechanical Characterization and Interfacial Properties of Okra Fiber Reinforced Polypropylene Composites

In this study, an attempt has been taken to manufacture okra fiber (OF) composites with varying the fiber content ranging from 25-65% on total weight of the composites and polypropylene (PP) was preferred as matrix material. To fabricate the composites untreated and mercerized fibers were selected. A systematic study was done to observe the mechanical behaviors of the composites such as tensile, impact and bending properties. It was found that treated (mercerized) fiber composites exhibited improved mechanical properties than that of untreated fiber composites. Maximum tensile strength (TS) and bending strength (BS) was examined 38.5 MPa and 72.5 MPa respectively, whereas the highest tensile modulus (TM) and bending modulus (BM) was observed 675 MPa and 5.4 GPa respectively. The optimum impact strength (IS) and hardness value was found to be 22.87 KJ/m2 and 97 (Shore-A) for mercerized fiber composites containing 45% fiber. The composite samples were exposed to different intensities of γ radiation (2.5 kGy–10.0 kGy) and found significant improvement in the mechanical properties up to 5.0 kGy dose. Water absorption, degradation properties due to heat and soil medium of the composites were also performed. The interfacial property was examined by Microscopic Projector and Scanning Electron Microscope (SEM) and found that the interfacial bonding between matrix material and fiber was enhanced due to the treatment of fibers which authenticate the found mechanical characteristics of the composites.