Presentation on theme: "THERMOPLASTICS - AIMS: To understand: What thermoplastics are… Why we use them… When we wouldn’t use them… and to identify examples of thermoplastics."— Presentation transcript:
THERMOPLASTICS - AIMS: To understand: What thermoplastics are… Why we use them… When we wouldn’t use them… and to identify examples of thermoplastics in use.
WHAT ARE THERMOPLASTICS? Thermoplastics are plastics that can be MELTED and RESHAPED when HEATED but HARDEN again when COOLED. MELT / FREEZE cycle
WHY DO WE USE THEM? Thermoplastics soften and MELT at quite low temperatures (as low as 100ºC) so they’re easy to manipulate. The MELT / FREEZE cycle can be repeated many times over, so they’re great for RECYCLING. They can be used for a range of different manufacturing techniques.
EXAMPLES: Acrylic - hard, clear, good optical properties (can be used for lighting) easily machined, polishes well. Light up signs Display stands
EXAMPLES: High Impact Polystyrene (HIPS) - Light, hard, stiff, water resistant, can be transparent or coloured. CD caseAudio tape casing
EXAMPLES: High Density Polythene (HDPE) - stiff, strong plastic, can be easily coloured and is often used for toys. UtensilsToys
EXAMPLES: Acrylonitrile butadienestyrene (ABS) - high impact strength, tough, scratch and chemical resistant. Household Appliances
WHEN would we avoid using thermoplastics? IN SITUATIONS WITH VERY HOT TEMPERATURES (ESPECIALLY OVER 400ºC) In these cases we tend to use thermosetting plastics which retain their form even in extreme heat.
QUIZ… WHICH TYPE OF THERMOPLASTIC… Acrylic, HIPS, HDPE or ABS?
THERMOPLASTICS - EVALUATION QUESTIONS: 1) What are thermoplastics? 2 ) Why do we use them? 3 ) When wouldn’t we use them? 4) identify one example of: HIPS Acrylic HDPS ABS and give reasons why it is used.