Plastics

Ikmalzatul Abdullah

Plastics1. Introduction2. Polymerisation process3. Types of plastics4. Properties5. Uses in construction

Objectives:To review, evaluate and analyses plastics based

on properties, economy, life and performance which used in construction industry

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Introduction

• Since the 1950’s plastics has grown to a major industry that effects all of our lives• Plastics remain the most versatile and energy efficient materials used today• Since 1976 plastic has become the most used material in the world

Material replacement Innovative uses/applications

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Cont..

• Plastics are by common consent taken to be mainly organic materials derived from petroleum and to small extent from coal, which at some stage in processing are plastic

when heated

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Cont..

• Like paints, rubbers and sealants, plastics consist of molecules joined together to form chain molecules, or polymers which are normally randomly coiled• Identical molecules or monomers, when polymerized, produce copolymers

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Plastics

•When oil is cracked ethene is often made.

•Ethene is a very useful molecule as it is the starting material for making many plastics.

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Cont..

•Plastics are huge molecules.

•They are usually made from chains of thousands of atoms.

•These long chains are called polymers

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Cont..

•Polymers are made from joining thousands of small molecules called monomers together.

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Cont..

•Ethene is a monomer that joins up to form poly(ethene).

•This reaction is called polymerisation

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Cont..

Monomer Polymer

ethene poly(ethene)

styrene poly(styrene)

vinyl chloride poly(vinyl chloride)

PVC

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History • Polyvinyl chloride was the first plastic. Polymerization was discovered by accident by

the French chemist Henri Regnault in 1838.• Bakelite plastic was the first really successful

plastic. It comprised mainly synthetic phenol formaldehyde resins and was patented in 1909.• Other milestones in plastics include the first

production of polystyrene in Germany in 1930, polyethylene and acrylates in 1993, polyester in 1942 and silicones in 1944

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Why Use Plastics?

• Plastics are light in weight and have goods strength; weight ratios, but rigidity is lower than that of virtually all other building materials

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Cont..

• Plastics have low thermal conductivity and thermal capacity, but thermal movement is high.• They resist a wide range of chemicals and do

not corrode but they tend to become brittle• Plastics are combustible.• Some are highly flammable while others such

as polyvinyl chloride, are difficult to burn

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Plastic is Polymer

• Plastics are Polymers of organic compounds or resins that can be mould into any shape by the application of heat and pressure.• All plastics are polymers; these polymers

are further divided into two basic types: Thermoplastics Thermosetting plastics

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Cont..

• Thermoplastics melt when heated – so they can be melted and re-formed again and again• Thermosetting plastics harden when they are

heated, if heated further, they will break down chemically and lose their properties.• Some Thermosetting plastics have properties

very similar to rubber, and are used as synthetic rubber; they are categorized as elastomers

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Cont..

• During production process substances such as chlorine, hydrochloric acid, fluorine, nitrogen, oxygen and sulfur are used, as well as oil-based chemicals.• Almost all plastics have a rich variety of

additives including plasticizers, pigments, stabilizers against solar radiation, preservatives and perfumes.

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Thermoplastics

A plastic material that can be soften when heated with pressure and can be re-mould into another shape. •General properties: low melting point, softer, flexible.•Typical uses: bottles, food wrappers, toys,..•Examples:Polyethylene: packaging, electrical insulation, milk and water bottles, packaging film

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Cont..

Polypropylene: carpet fiber, automotive bumpers, microwave containers, prosthetic body parts for disabled people

Polyvinyl chloride (PVC): sheating for electrical cables, floor and wall coverings, siding, credit cards, automobile instrument panels

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Thermosetting plastics

Thermosetting plastics have the property of becoming permanently hard and rigid when heated or cured. It cannot be softened or re-mould. The phenol resins and plastics were the original synthetic thermosetting materials.•General properties: more durable, harder, tough, and light.•Typical uses: automobile parts, construction materials.

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Cont..

• Examples: Unsaturated Polyesters: lacquers,

varnishes, boat hulls, furniture Epoxies and Resins: glues, coating of

electrical circuits, composite materials like fiberglass used in helicopter blades, boats, reinforcement and etc.

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Elastomers

• General properties: these are thermosetting plastics, and have rubber-like properties.• Typical uses: medical masks, gloves, rubber-

substitutes• Examples: Polyurethanes: mattress, cushion, insulation,

toys Silicones: surgical gloves, oxigen masks in

medical and other applications, joint seal

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