ABSTRACT

This study produced locust bean pods ash, synthesized from it nanoparticles which were subsequently used for the production of polyester matrix composite. It characterized the synthesized particulates and the composite produced. It also evaluated the effects of degradation of the composite subjected to different agents on mechanical properties such as hardness, tensile, flexural and impact strength. This was with a view to determining the degradability of the composite.Scanning Electron Microscopy (SEM) was used to characterize the synthesized nanoparticles and some testsamples (composite). The minimum average Particle size of the synthesized LBPA Nanoparticles was 52.4nm, which falls within the range of 1 – 100nm, the recommended particle size required for a material to be classified as Nanomaterial. The mechanical properties of the control samples increased as the reinforcement was increased from 0%LBPA – 12%LBPA; the impact, tensile and flexural strengths increased from 0.03 – 0.37J/m, 4.30 – 6.84MPa and 10.75 – 14.17MPa, respectively. The mechanical properties of buried and weathered samples decreased with increase in reinforcement (from 0%LBPA – 12%LBPA) and exposure time (90days). The impact, tensile, flexural and hardness values of the buried samples decreased from 0.04 – 0.023J/m, 32 – 10MPa, 47.27 – 16.47MPa and 8.7 – 6.5HRF indicating 43, 69, 65 and 25% decrease,espectively. Similarly, decreases were observed in the impact, tensile, flexural and hardness values of the weathered samples from 0.05 – 0.023J/m, 28 – 12MPa, 62.13 – 8.73MPa and 11.6 – 6.6HRF indicating a decrease of 54, 57, 86 and 43% decrease, respectively. It was noted that the composite became more susceptible to degradation with increase in reinforcement. The swelling and shrinking of natural filler when exposed to natural weather and activities of microorganisms in the soil might have been responsible for the decrease in their properties. The rate of moisture absorption of the composite samples increased with increase in reinforcement; the highest value of 1.42% was obtained at 12%LBPA. The percentage by weight losses for the impact, tensile, flexural and hardness tests samples after soil burial and weathering were respectively, 0.55, 1.01, 0.09, 0.77 and 0.35, 0.93, 0.14, 0.42% after 90days of exposure. SEM examinations of the weathered and buried samples showed roughened surfaces with some voids and pits observed on the soil buried samples. 

CHAPTER ONE

1.0                                                       INTRODUCTION

The continuous growth in modern technology calls for materials with unusual combination of properties that cannot be met by most of the conventional metals, alloys, ceramics and polymeric materials. This is especially true for materials needed for the aerospace, underwater and transportation applications. Most industries are increasingly searching for materials that are light, strong, stiff, abrasion and impact resistant and are not easily corroded as may be required in the aerospace industry (Mishra et al., 2002).

Over the last three decades, composites materials, plastic and ceramics have been the dominant emerging materials. The number of applications of composites particularly polymeric composites reinforced with synthetic fibers such as glass, carbon and aramid has grown steadily due to their unique properties of high stiffness and strength-to-weight ratio (Mishra et al., 2002).

Furthermore, polymers have substituted many conventional materials. They are used in many applications due to the advantages they have over conventional materials; ease of processing, high performance, low cost and versatility. However, for some specific uses, some mechanical properties such as strength and toughness of polymer materials are inadequate. Various approaches have been developed to improve such properties. In most of these applications, the properties of polymers are modified using fillers and fibers to suit the high strength/high modulus requirements. In polymer matrix composites, fibrous materials e.g. synthetic or natural fibers, serve either as filler or reinforcement by giving strength and stiffness to the base material; while the polymer matrix serves as the adhesive to hold the fibers in place (Taj, 2011).  The shift of composite application from aircraft to other commercial uses has become prominent in recent years, increasingly enabled by the introduction of newer polymer resin matrix materials and high performance reinforcement fibers of glass, carbon and aramid. The industrial uses of.