ABSTRACT

Mechanical and morphological properties of pure polypropylene (PP) polypropylene/calcium carbonate (PP/CaCO3) and polypropylene/cashew nutshell powder (PP/CNSP)are reported in this work. The composites were prepared by compression moulding technique. The compressed moulded articles that is the PP, (PP/CaCO3) and (PP/CNSP) of different compositions (10/90, 20/80, 30/70, 40/60, 50/50, 60/40, 70/30, 80/20) were characterised for mechanical properties, water absorption capacity, structural characterisation and morphological arrangements. Comparative studies was made on the mechanical properties of the pure polypropylene (PP), polypropylene/calcium carbonate (PP/CaCO3) and polypropylene/cashew nutshell powder (PP/CNSP). Mechanical properties such as tensile strength, Young‟s modulus and percentage elongation at break, Hardness behaviour and Impact resistance of both PP/CaCO3 and PP/CNSP composites increased with increment of filler weight content (10-50g). It was noted that the specimen samples of ratio50/40 PP/CaCO3 and PP/CNSP had the highest tensile strength, when compared with other sample. These specimens could bear loads of 1075N and 468N with extensions of 4.44mm and 6.12mm respectively. Decrease in the mechanical properties were noted on continuous addition of both fillers, with drastic reduction of the mechanical properties at (70g and 80g) fillers weight except hardness that slightly increased at all the filler loading (10-80g). The surface sorption characteristics of calcium carbonate and cashew nutshell powder have been investigated and the highest percentage was recorded at 20/80 of PP/CNSP (100%). Scanning electron microscopy (SEM) revealed that, both 60/40 PP/CaCO3, PP/CNSP and 50/50 PP/CaCO3, PP/CNSP are completely compatible at which there are no phases that are grossly separated. X-ray diffraction analysis showed that, the incorporation of the two fillers into the neat polypropylene decreased the crystallinity of the polypropylene and the crystallinity decreases with increasing filler loading.

CHAPTER ONE

INTRODUCTION

1.1 Background of the Study

Particle reinforced plastics composites (PRPCs) are composites to which fillers (discrete particles) have been added to modify or improve the properties of the matrix and/or replace some of the matrix volume with a less expensive material. Common applications of PRPCs include structural materials in construction, packaging, automobile tires, medicine, etc. Determination of effective properties of composites is an essential problem in many engineering applications (Van, 2003 and Love, 2004).

These properties are influenced by the size, shape, properties and spatial distributions of the reinforcement (Liu, 1995 and Lee, 1998).

Modification of organic polymers through incorporation of additives yield, with few exceptions, multiphase systems containing the additive embedded in a continuous polymeric matrix. The resulting mixtures are characterised by unique microstructures that are responsible for their properties. Polymer composites are mixtures of polymers with inorganic or organic additives having certain geometries. Thus, they consist of two or more components and two or more phases. In addition to polymer composites, other important types of modified polymer systems include polymer-polymer blends and polymeric forms. Blending procedures had been employed since time immemorial. The principle of blending is geared towards achieving property averaging. A blend is therefore the physical mixture of two or more substances, without a chemical bond, (Mamza, 2011).

Among the various studies carried out with particle filled PP worth mentioning, are works by Maiti and Mahapatro (1992 and 2011) on the tensile and impact behaviour of nickel powder-filled PP and CaCO3 filled PP composites. It was discovered that the addition of nickel-powder causes decrease in tensile modulus, tensile strength and elongation-at-break with increasing filler. In the case of the addition of CaCO3, tensile modulus increased while tensile strength and elongation-at-break decreased with increasing filler. Izod impact strength for the composites at first application of filler loading increased up to a critical filler content, beyond which the value decreased appreciably.

The filler cashew nutshell powder (CNSP) has been under utilised, in composite formulation, as it is considered as waste material especially in the Northern part of Nigeria. Thus, there is need to convert this waste to wealth meanwhile this conversion would serve as an environmental waste control.

The main aim of this work was to determine the impact resistance of cashew nutshell powder and calcium carbonate used as fillers for polypropylene.

The specific objectives of the study are;

1. Collection of samples from the outlet centre and preparation of samples.
2. Determination and characterisation of cashew nutshell powder using X-ray diffraction analysis.
3. To carry out mechanical tests such as hardness, tensile strength, elongation at break, impact resistance and to carry out sorption test on the produced samples,
4. Determination of microstructure of the processed samples using scanning electron microscopy (SEM).

Cashew nut shell powder as one of the fillers used in this research can reduce the cost of production of articles compared to the commercially available fillers. It can create job opportunity locally, by paying people supplying it for the researchers. The use of cashew nutshell powder as filler can help to reduce environmental pollution caused by the shell, this is because, it is biodegradable and it can decay and becomes a pollutant to the society.

1. To prepare and characterise CNSP filler
2. To fill cashew nutshell powder in polypropylene
3. To fill calcium carbonate in polypropylene
4. To carry out mechanical tests on the prepared composite, such as hardness, tensile strength, elongation at break, sorption test, and impact resistance
5. To compare the impact resistance of cashew nutshell powder and calcium carbonate filled polypropylene