2 What are they ? Why are they so popular? Where do they come from? A synthetic material made from a wide range of organic polymers such as polyethylene, PVC, nylon, etcIts cheap, durable, versatile and can be shaped to form whatever the manufacturer needs it to be. Unlike other materials such as glass, the process is faster. Generally speaking it can also be reused and recycled.Plastics can be either found in natural substances or may be man-made. Most of the plastics used today are man-made. Man-made plastics are known as synthetic plastics which is mainly sourced from crude Oil. Natural plastic products occur in such things as animals' horns, animals' milk, insects, plants and treesWhy are they so popular?Where do they come from?
4 What are the main types? Plastics can be divided into two main types: Thermoset or thermosetting plastics. Once cooled and hardened, these plastics keep their shapes and cannot return to their original form by re heating. They are hard and durable. Main examples are polyurethanes, polyesters, epoxy resins.Thermoplastics. Less rigid than thermosets, thermoplastics can soften upon heating and return to their original form. They are easily moulded and extruded into films, fibers and packaging. Again the main examples include polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).
5 Attributes and Applications PET SymbolAbbreviationAttributes and ApplicationsPETPolyethylene terephthalate – (mainly clear/ transparent plastic) Fizzy drink bottles, squash bottles, some shower-gel bottles and some food containers/packaging.HDPEHigh-density polyethylene – (Mainly opaque plastic) Bottles for milk, some milk bottle tops, some washing-up liquids, and some shampoo bottles.PVCPolyvinyl chloride - Food trays, cling film, bottles for squash, mineral water and shampoo.LDPELow density polyethylene - Carrier bags and bin liners.PPPolypropylene - Margarine tubs, microwaveable meal trays.PSPolystyrene - Yoghurt pots, foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery, protective packaging for electronic goods and toys.OTHERAny other plastics that do not fall into any of the above categories. - An example is melamine, which is often used in plastic plates and cups.
6 Strong, insulator, brittle, hard, stiff. Name PropertiesApplications and UsesUrea formaldehydeStrong, insulator, brittle, hard, stiff.Electrical fittings. Handles and knobsPolyester resinLiquid raw state, stiff hard, insulator, chemical resistance, brittle without fibre reinforcement.Casting, bonding fibres- glass, Kevlar, carbon fibre.Epoxy resins-trade names include araldite.Good insulator, brittle chemical resistant.adhesives, bonding fibres, encapsulation.Melamine formaldehydeHard, strong, heat resistant.
7 How do we improve the properties of plastics ? One way to improve the performance characteristics of plastic products is to compound resins with additives and fillers. Additives help fight against factors such as heat, chemicals, or light. There are thousands of additives/fillers on the market today. Below are some of the most common ones used in manufacturing.Antimicrobials: Used to control the build up of bacteria, fungi and algae on the surface of plastic products. A wide range of chemical and natural compounds are used as antimicrobials. An example would be naturally occurring silver ions used in products such as cell phones or organic acids in food-related products.Antioxidants: Used to control the degradation of products due to air exposure.Antistatic: Used to minimize static electricity. These types of additives can be mixed with the resin or applied to the surface of the product. Antistatic additives are common to a wide variety of products ranging from cosmetics to industrial goods to sensitive electronic parts.Electrostatic Induction: Used for the economical and even application of polyurethane paints to consumer goods such as automobiles, bicycles, and others.Fibres: Used to increase strength and stiffness. The most common type of fibres added for strength would be carbon and glass. Glass-reinforced plastic is more commonly known and marketed as fiberglass.Conductive fibres: Used to provide special properties for certain applications.Plasticizers: Added to make products softer and more flexible. Some plasticizers evaporate and tend to concentrate in an enclosed space; the "new car smell" is caused mostly by plasticizers evaporating from the car interior.Lubricants: Used for easier moulding or for increased adhesion and viscosity of the moulded parts.UV stabilizers: Used for the protection of the resin’s mechanical properties by absorbing selective UV rays resulting in less degradation.Fillers: An inexpensive substance such as wood, metal, glass or clay that is added to plastics in very small particles to decrease cost, improve hardness, stiffness, and impact strength.Flame retardants / Smoke suppressants: A variety of chemicals that can be added to resins to eliminate its tendency to burn. For polyethylene and similar resins, chemicals such as antimony trioxide and chlorinated paraffin are useful.Colorants: Used to add colour, special effects, or patterns to plastic products.
8 Useful Links1. Plastics, Fuels and Chemicals from Crude Oil2. The Oil Refinery and Distillation Tower3. The Manufacture and Nature of Plastics4. Crude Oil to Fuels and Plastics - Summary Diagram5. Thermoplastic Elastomers (TPEs)6. Properties of Thermoplastic Elastomers (TPEs)7. Examination Question - Thermoplastic Elastomers8. Renewable and Environmentally Friendly Polylactide9. Polylactide - Life Cycle10. Polylactide - Examination Question11. Polyethylene Terephthalate or PET / PETE (Polyester)12. Polyethylene Terephthalate or PET / PETE - Examination Question13. Vacuum Forming PETE Packaging - Examination Question14. Examination Question (Part One) - Injection Moulding HIPS, HDPE, LDPE, PP, Acrylic (PMMA), ABS.15. Examination Question (Part Two) - Injection Moulding HIPS, HDPE, LDPE, PP, Acrylic (PMMA), ABS.16. Examination Question - Polypropylene Packaging17. Low Density Polyethylene Questions18. LDPE and Extrusion Blow Moulding19. Extrusion Blow Moulding - Question - 120. Extrusion Blow Moulding - Question - 220. Further Questions and Answers on Plastics
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