CHAPTER ONE

INTRODUCTION

Polyurethane foam otherwise known as expanded polymer products are group of materials developed as gotten by there action between alcohol with two or more reactive hydroxyl group per molecule. This branch of polymer technology are finding increasing applications in many field of engineering including arts and sciences. Foam was discovered as a result of man’s strong desire in quest to his environment. There are many kinds of foam based on their inherent features such as high rigidity, stiffness per unit weight of polymer thermal and acoustical insulating properties. Cushioning properties or shock absorbency characteristics, low internal stresses of foamed mouldings and ease of forming. As a result of these, extensive range of materials and manufactured articles with different applications are produced from polymer.

The three types of foams are flexible, rigid and semi-rigid foams. It’s used in many structural applications where they form light weight care. Cellular products contains gas usually air, within their structures, they have lower thermal conductivity and are therefore good thermal insulants. Because foams able to dissipate energy reversible and storage capacity. They are used in cushions and are exploited in upholstery bedding laminated clothing and packaging.

Every polymer can be produced in cellular form but these that have been extensively used includes, polyurethane, polystyrene, polyethylene, polyethylene, poly- (vinyl chloride), cellulose acetate, phenolies epoxides, urea-formaldehyde resins, silicones naturally rubber e.g. later from which is made from liquid starting material; sponge rubber and expanded rubber, both made from solid materials.  Cellular plastics are basically of two types, flexible foam and rigid or structural foam.  They may also be classified according to density as low density foam (< 100kg/m3), medium density foam (600-1000kg/m3).

Cellular polymers may have either an open-cell structure in which the cells are closed separate units (unicellular foams) and may contain gas or air.  Materials with open-cell structures have high permeability’s to liquid and gases but because closed – cell structures contains air, their elastic moduli in compression are higher and they have the best thermal insulations.

Polyethylene foams can be produced by injection moulding or may be processed by special machines designed to measure the required ratio of chemical, mixing them together and dispense the reaction mixture in predetermined amounts.  There has been continuous development of machine for processing along side the development of polyethylene technology.

Based on the environmental impact and protechona, new dimensions to further challenges in the development of polyethylene technology has taken place which have contributed to the increasing application of polyethylene in our daily lives from foam resistant coating.

As a matter of facts, this research project is centered on flexible foam of higher density and characterization and different types of polymeric reactions could produce different materials like plastics rubber, filmos, fire surface coating and adhesive.  As a result of variation in reaction hydroxyl groups of alcohol and isocyanate, senies of polyethylene products have been produced.  This ranges from flexible soft and revilement material to hard, brittle and rigid.

Generally, four bare isocyanates and a range of polyol of different molecular weight and functionalities are used in the production of whole spectrum of polyethylene products/materials.

As the case may be, various types of foams with different characteristics features are produced by varying the medium, mixing ratio etc.

1.1             PROBLEM STATEMENT

Based on the fact that some raw materials are gotten from out petrochenueal industries/chemical industries, these unused materials are property channeled to effective use in producing polymer materials e.g. foam, such materials are toluenemdi-isocyanata, polyether, resin, polyol, etc.

1.2             AIMS AND OBJECTIVES OF THE PROJECT

This project/research is aimed at producing polyethylene foam that could be used or applied in various fields to satisfy human wants in Nigeria particularly and the world in general.

It is expected that if this research project is successful, a medium-layer scale industries would be established to best foam production.

Thirdly, an employment opportunity would be created for many Nigerians and would also bring foreign exchange to the country and also attract foreign investors to come into Nigeria.

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