Abstract
D.Ing. (Mechanical Engineering)
In recent years, there has been increasing worldwide interest in the advance of new technologies concerning the use of products that cause lower environmental impact. In this context, particular attention has focused on synthetic fibre composites materials since they lead to several questions that require attention, particularly onbiodegradability
and the difficulty of recycling, which ends up by generating vast increases of this type of material in deposits, garbage dumps, and in the environment itself. In the search for a solution to this problem, various researches and works in the area of polymeric composites have and are still being conducted to ensure environmental protection. The researches in this area that have been growing and stand out are those that seek applications for natural modifiers, mainly in terms of the use of natural fibres. Importance should be given to the use of natural fibres of plant origin, due to the enormous biodiversity of available plants that can be investigated and because they represent a renewable resource. Several natural plant fibres are produced in almost every country. A number of products are being developed using natural plant fibres, mainly for internal finishing parts for vehicles, where other mechanical, thermal and acoustic properties are relevant. In the present dissertation author characterized native African Napier grass fibre strands and analyzed their properties to assess their suitability as reinforcement in the polymer composites. In this direction, the author selected the native African Napier grass fibre as the reinforcement. Napier grass fibre strands were characterized using NaOH and acetic acid treatment. Fourier transform
infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction analysis (XRD), Thermo gravimetric analysis (TGA), Chemical analysis,and Tensile testing techniques were used to characterize untreated, NaOH (5, 10, and 15%) and acetic acid (5, 10, and 15%) treated fibre strands. Of both treatments in the present work, it was observed that NaOH treatment contributes better characteristics over acetic acid treatment. Therefore, the NaOH treated native African Napier grass fibre strands were used to produce composites with epoxy resin as matrix material using hand lay-up technique. Epoxy (LY-556) of density 1.15 g/cm3 matrix and hardener (HY-951) of density 0.98 g/cm3 were used to fabricate the composite. The weight ratio of 100:15 was used to mix epoxy and hardener respectively. In the present work, the composite laminates were prepared with weights of 10, 20, and 30% of untreated and sodium hydroxide treated Napier grass fibre strands with long fibre strands (unidirectional) and short fibre strands (random orientation). Composites were characterized using Scanning electron microscopy, Chemical resistance, Water absorption and Tensile test. The effect of NaOH
treatment of the fibres on the mechanical properties of the resulted composites was
also studied in this work. The ASTM procedures were followed in the preparation
and testing of the specimens. The author also investigated the bonding between the
matrix and the reinforcement, for this the author recorded the scanning electron
micrograms of fractured samples. The NaOH treatment of the Napier grass fibre
strands was found to refine its mechanical properties and this favors its application
in the automobile industry.