1. Plastics & Adhesives

2. Plastics can be derived from Coal Natural Gas Other Petroleum Products Cotton Wood Waste Organic Matter

3. From the base product monomers are extracted. These monomers react with each other to form chains which are called polymers See diagram page 1

4. Development Plastics are being used in many facets of our industry Where do we see plastic?

5. Two Types of Plastic 1.Thermoplastics 2.Thermosetting Plastics

6. Types of Plastic 1.Thermoplastics Become Soft when heated Reharden when cooled This process can be repeated to allow the plastic to be moulded or formed to a required shape Constant Cooling & Reheating will affect it’s appearance & Strength Soften then catch fire

7. Types of Plastic 2. Thermosetting plastics (Thermosets) Undergo a irreversible chemical change during production Will not soften when heated Will not soften before catching fire Cannot be moulded or bent to shape

8. Properties of Plastics Strength – High Tensile Strength to weight ration Due to elasticity they are not suitable for structural applications Heat will also degrade when heat applied Thermal Expansion can be as much as 10 x steel

9. Properties of Plastics Thermal Conductivity Expanded Plastic has Low Thermal Conductivity Foamed Plastics are good insulators

10. Properties of Plastics Electrical Properties Non Conductors Will build up Electrostatic Charges Attract Charges Sparking Can Occur- This has OH&S Implications

11. Properties of Plastics Combustibility Will catch fire when open flame applied Will propagate fire Additives can be used to retard fire- usually will still burn when open flame applied and self extinguish when flame removed. Gases emitted are toxic Some plastic will melt and cause injury

12. Properties of Plastics Durability Do not corrode Will be degraded by UV radiation which will break down the plastic Plastic for External use must be UV stabilised

13. Properties of Plastics Environmental Hazards Not Biodegradable May be recycled Burning released toxic gases

14. Plastics in the Building Industry Polythene – Builders Plastic- Concrete Underlay – Thermoplastic Polyvinyl Chloride – PVC Pipes, Roof & Wall sheeting, Vinyl Floor Covering, Electric Cabling Resistant to Fire

15. Plastics in the Building Industry Polyvinyl Acetate (PVA), Glue, Curing Compound, Bonding agent for Plaster, Insitu Floor Coverings Polymethyl Methacrylate (Acrylic) – Roof Sheeting Polystyrene – Insulation, Form Voids in concrete – easily dissolved by organic solvents

16. Plastics in the Building Industry Teflons – Resistant to heat, very low friction, plumbers tape Nylons – Nuts, bolts, Carpets, Door Fittings Polycarbonates – High Ductility, High Tensile, Roof Sheeting, Bullet Proof Glass

17. Plastics in the Building Industry Bakelite –, Thermosetting Oldest form of plastic, Electrical fittings, resistant to ignition Resorcinal Formaldehyde – Waterproof & Boil proof Glue Polystyrene – Insulation, Form Voids in concrete – easily dissolved by organic solvents

18. Adhesives Originally based on animal and vegetable matter – Horse Glue! Last 20 years synthetic glues developed that provide high stress bonds

19. General Properties Properties vary Some are Highly Flammable eg Contact Adhesives Liquid Nails is Flammable and degrade polystyrene while Liquid Nails Fast Grab is not flammable and will not degrade polystyrene

20. Types of Adhesives Adhesives from Natural Products Wall paper paste based on cellulose Only suitable for Interior use Susceptible to attack by micro- organisms

21. Types of Adhesives Adhesives from Natural Products Bituminous Adhesives resistant to water and many chemicals May reactivate under heat Used for Vinyl & Parquetry Bonding of Roof Felt