Notes. air. oil. Resistant Materials Plastics. resins. granules. There are two basic types of plastic: thermosetting plastic and thermoplastic.

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1 Resistant Materials Plastics Notes Plastics There are two basic types of plastic: thermosetting plastic and thermoplastic. Plastics are produced from the following ingredients Oil, Air, Water and Salt. The ingredients are processed to produce powders, granules and resins. The addition of dyes produce a large range of colours. Although thermosetting plastic and thermoplastic come from the same ingredients, the two materials have very different properties. properties thermosetting salt water processed resins granules air thermoplastic oil

2 Thermosetting Plastics The most important thing about thermosetting plastics is their resistance to heat. Once formed into a shape they cannot be re-shaped. These plastics are used in situations where strength and resistance to heat is very important. Although they are generally quite hard, they can be easily chipped or cracked by being dropped or banged. banged formed cracked dropped strength resistance heat Thermosetting Plastics The following are some common thermosetting plastics. Polyester Resin Epoxy Resin Melamine formaldehyde Phenol formaldehyde Urea formaldehyde

3 Polyester Resins Polyester comes as a thick liquid. This can be used in two ways. The clear version of this resin is used for casting as when making a paperweight. The resin can also be used along with sheets of glass fibre matting to make glass reinforced plastic (GRP) mouldings, e.g. boat hulls and car bodies. Epoxy resin This is used to make glues. Two examples are: Araldite - which sticks most things. Aerolite - a waterproof wood glue.

4 Melamine Formaldehyde This is a durable, heat resistant plastic. It is used for kitchen work surfaces, good quality plastic cups, dishes, tumblers, trays, etc. Phenol Formaldehyde Dark, hard and quite brittle, it is used for saucepan handles and some electrical fittings.

5 Urea Formaldehyde Usually white in colour, it is tough yet attractive to look at. Urea formaldehyde is used in the manufacture of good quality electrical fittings, such as mains sockets, plugs, light switches, etc. Thermoplastics Thermoplastics can be easily reshaped with the application of heat and, for this reason, they cannot be used in situations where they will get hot. hot cannot reshaped heat situations Despite this, they have been used in many hundreds of examples where resistance to heat is not a problem, such as moulded chairs.

6 Thermoplastics The following are some common thermoplastics. Acrylic Rigid Polystyrene Expanded Polystyrene Rigid PVC Flexible PVC High Density Polythene Low Density Polythene Acrylic Also known by its tradename, PERSPEX, acrylic is a versatile plastic which is used for many items such as shop signs, baths and jewellery. Underwater restaurant Ithaa, five meters below sealevel, is encased in acrylic. It is also used a lot in Technology projects, because it can be worked and formed easily, in so many ways. It comes as clear, opaque or semitransparent sheets, in thicknesses from 2 to 6mm. When finished properly, it is colourful and attractive to look at.

7 Rigid Polystyrene Most often used for containers, such as cosmetic and shampoo bottles. It is also used for TV cabinets and as thin sheets to make disposable drinking cups. It is used in Technology projects to make simple polystyrene shapes by vacuum forming. Expanded Polystyrene Most commonly seen as the white granular packing used to prevent damage to expensive or fragile goods in transit.

8 Rigid PVC Polyvinyl chloride Rigid PVC is mostly used for drain pipes and guttering. Flexible PVC Flexible PVC is used in the manufacture of inflatable dinghies, hose pipes, cheap shoes and upholstery material.

9 Polythene Can be moulded into almost any form due to its excellent moulding qualities. Used for the production of bottles, bowls, toys, tube etc. It is available in large sheets. There are two types: High density which is rigid and hard, and low density which is tough and flexible. High density Polythene