Alkaline Surface Modification of Banana Stem Fibres

One of the important issues in producing composite materials with natural fibres is the modification of the surface of the fibres to enhance adhesion and interfacial bonding with polymer matrix. In this report, the effect of alkalization on the mechanical properties, thermal stability and surface morphology of banana stem fibres is examined. The results show that treatment with sodium hydroxide modified the surface of the fibre, attenuating IR absorption intensities at 1733cm corresponding to reduction of C=O groups, at 1514cm and between 3000 and 2850cm associated with reduction/removal of low molecular weight constituents of the fibres. It was found that alkali-treatment improved both tensile and flexural strengths, and the thermal stability of the fibres. INTRODUCTION Polymer matrix composites are made by embedding fibres such as carbon, aramid or glass in a polymer matrix. Carbon fibres have remarkable properties with tensile strength of 3.2 GPa and a tensile modulus of 230 GPa. The high stiffness and strength of this material makes it ideal for many applications in the defense and aerospace industries and in civilian applications. The disadvantages of carbon fibres are their high cost and brittle nature. Glass fibres are the most widely used fibres for general reinforcement of polymers and while not as strong as carbon fibres, glass produces desirable properties in composites such as cost. Because of increasing environmental consciousness and demands of legislative authorities, there is a paradigm shift towards designing materials that are compatible with the environment. * Author for correspondence The use of natural fibres as replacement for synthetic fibres has thus received considerable research attention. Although carbon fibres remain superior to natural fibres in high-end applications, natural fibres have comparable properties to glass fibres in high volume applications. Natural fibres are complex in structure, whose characteristic properties vary considerably, and depend on whether the fibres are taken from plant stem or leaves, quality of plant location, the age of the plant, etc. Depending on their origin, natural fibres may be grouped into leaf (e.g. sisal, pineapple leaf), bast (flax, hemp, jute), seed (cotton), fruit (coconut coir). Natural fibres are lignocellulosic, consisting of helically wound cellulosic microfibrils in an amorphous matrix of lignin and hemicellulose. Lignocellulosic materials are the most abundant renewable biomaterial of photosynthesis, with annual production estimated at 2.0x10 tons (compared to 1.5x10 tons of synthetic polymers) and are widely distributed in the biosphere in the form of