2 Plastics Introduction Polymerisation process Types of plastics PropertiesUses in constructionObjectives:To review, evaluate and analyses plastics based on properties, economy, life and performance which used in construction industry
3 IntroductionSince the 1950’s plastics has grown to a major industry that effects all of our livesPlastics remain the most versatile and energy efficient materials used todaySince 1976 plastic has become the most used material in the worldMaterial replacementInnovative uses/applications
4 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 plasticwhen heated
5 Cont..Like paints, rubbers and sealants, plastics consist of molecules joined together to form chain molecules, or polymers which are normally randomly coiledIdentical molecules or monomers, when polymerized, produce copolymers
6 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.
7 Cont.. Plastics are huge molecules. They are usually made from chains of thousands of atoms.These long chains are called polymers
8 Cont..Polymers are made from joining thousands of small molecules called monomers together.
9 Cont.. Ethene is a monomer that joins up to form poly(ethene). This reaction is called polymerisation
11 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 and silicones in 1944
12 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
13 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 brittlePlastics are combustible.Some are highly flammable while others such as polyvinyl chloride, are difficult to burn
14 Plastic is PolymerPlastics 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:ThermoplasticsThermosetting plastics
15 Cont..Thermoplastics melt when heated – so they can be melted and re-formed again and againThermosetting 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
16 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.
17 ThermoplasticsA 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
18 Cont..Polypropylene: carpet fiber, automotive bumpers, microwave containers, prosthetic body parts for disabled peoplePolyvinyl chloride (PVC): sheating for electrical cables, floor and wall coverings, siding, credit cards, automobile instrument panels
19 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.
20 Cont..Examples:Unsaturated Polyesters: lacquers, varnishes, boat hulls, furnitureEpoxies and Resins: glues, coating of electrical circuits, composite materials like fiberglass used in helicopter blades, boats, reinforcement and etc.
21 ElastomersGeneral properties: these are thermosetting plastics, and have rubber-like properties.Typical uses: medical masks, gloves, rubber- substitutesExamples:Polyurethanes: mattress, cushion, insulation, toysSilicones: surgical gloves, oxigen masks in medical and other applications, joint seal