Short Communication Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites N. Venkateshwaran a,⇑ , A. ElayaPerumal a , A. Alavudeen b , M. Thiruchitrambalam c a Department of Mechanical Engineering, Anna University, India b Department of Mechanical Engineering, Kalasalingam University, India c Department of Mechanical Engineering, TamilNadu College of Engineering, India article info Article history: Received 26 November 2010 Accepted 1 March 2011 Available online 6 March 2011 abstract The tensile, flexural, impact and water absorption tests were carried out using banana/epoxy composite material. Initially, optimum fiber length and weight percentage were determined. To improve the mechanical properties, banana fiber was hybridised with sisal fiber. This study showed that addition of sisal fiber in banana/epoxy composites of up to 50% by weight results in increasing the mechanical prop- erties and decreasing the moisture absorption property. Morphological analysis was carried out to observe fracture behaviour and fiber pull-out of the samples using scanning electron microscope. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Natural fiber composites combine plant-derived fibers with a plastic binder. The natural fiber components may be wood, sisal, hemp, coconut, cotton, kenaf, flax, jute, abaca, banana leaf fibers, bamboo, wheat straw or other fibrous material. The advantages of natural fiber composites include lightweight, low-energy pro- duction, and environmental friendly; to name a few. The use of natural fibers reduces weight by 10% and lowers the energy needed for production by 80%, while the cost of the component is 5% lower than the comparable fiber glass-reinforced compo- nent [1]. In the past, composites of coconut fiber/natural rubber latex were extensively used by the automotive industry. How- ever, during the seventies and eighties, newly developed syn- thetic fibers due to better performance gradually substituted cellulose fibers. For the past few years, there has been a renewed interest in using these fibers as reinforcement materials, to some extent in the plastic industry. This resurgence of interest may be attributed to the increasing cost of plastics and the environmen- tal aspects associated with using renewable and biodegradable materials [2]. Mechanical properties of banana fiber were studied by Kulk- arni et.al [3]. They observed that the failure of banana fiber in tension is due to pull-out of microfibrils accompanied by tearing of cell walls. The tendency for fiber pull-out decrease with increasing speed of testing. Nilza et.al [4] investigated the poten- tials of banana, coir and bagasse fibers in composites. In their work, fiber samples were subjected to standardized characterisa- tion tests such as ash and carbon content, water absorption, moisture content, tensile strength, elemental analysis and chem- ical analysis. Results revealed that the banana fiber exhibited the highest ash, carbon and cellulose content, hardness and tensile strength, while coconut the highest lignin content. Venkateshw- aran and ElayaPerumal [5] reviewed the various work carried out so far in the field of banana fiber polymer composite. The paper revealed the structure, physical and mechanical properties of banana fiber composite. Further, it says that very few works on banana fiber reinforced with epoxy resin was carried out. Sreekala et.al [6] investigated the performance of mechanical properties of oil palm fiber with glass fiber and used phenol form- aldehyde as resin. The investigation revealed that maximum mechanical performance occurs at 40 wt% loading. Kasama and Nitina [7] studied the effect of glass fiber hybridisation on proper- ties of sisal fiber–polypropylene composites. Incorporation of glass fiber increases the mechanical, thermal and water resistance properties. In this work, the experiments were conducted for predicting the fiber length and weight percentage gives the maximum mechani- cal properties are investigated initially. Composite specimens were prepared by varying the fiber length (5, 10, 15 and 20 mm) and weight percentages (8, 12, 16, and 20). Further, to improve the mechanical properties of the banana/epoxy composites, sisal fibers were added at different weight ratio (25, 50 and 75%). Hybridisa- tion by sisal fibers yields positive improvement in mechanical properties. 0261-3069/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.matdes.2011.03.002 ⇑ Corresponding author. Tel.: +91 9444325794; fax: +91 44 2235169. E-mail address: venkatcad@yahoo.com (N. Venkateshwaran). URLs: http://www.annauniv.edu (N. Venkateshwaran), http://www.annauniv. edu (A. ElayaPerumal), http://www.kalasalingam.ac.in (A. Alavudeen), http:// www.tnce.in (M. Thiruchitrambalam). Materials and Design 32 (2011) 4017–4021 Contents lists available at ScienceDirect Materials and Design journal homepage: www.elsevier.com/locate/matdes