Slide 2 THERMOPLASTICS - AIMS: To understand: What thermoplastics are Why we use them When we wouldnt use them and to identify examples of thermoplastics in use. Slide 3 WHAT ARE THERMOPLASTICS? Thermoplastics are plastics that can be MELTED and RESHAPED when HEATED but HARDEN again when COOLED. MELT / FREEZE cycle Slide 4 WHY DO WE USE THEM? Thermoplastics soften and MELT at quite low temperatures (as low as 100C) so theyre easy to manipulate. The MELT / FREEZE cycle can be repeated many times over, so theyre great for RECYCLING. They can be used for a range of different manufacturing techniques. Slide 5 EXAMPLES: Acrylic - hard, clear, good optical properties (can be used for lighting) easily machined, polishes well. Light up signs Display stands Slide 6 EXAMPLES: High Impact Polystyrene (HIPS) - Light, hard, stiff, water resistant, can be transparent or coloured. CD caseAudio tape casing Slide 7 EXAMPLES: High Density Polythene (HDPE) - stiff, strong plastic, can be easily coloured and is often used for toys. UtensilsToys Slide 8 EXAMPLES: Acrylonitrile butadienestyrene (ABS) - high impact strength, tough, scratch and chemical resistant. Household Appliances Slide 9 WHEN would we avoid using thermoplastics? IN SITUATIONS WITH VERY HOT TEMPERATURES (ESPECIALLY OVER 400C) In these cases we tend to use thermosetting plastics which retain their form even in extreme heat. Slide 10 QUIZ WHICH TYPE OF THERMOPLASTIC Acrylic, HIPS, HDPE or ABS? Slide 11 ABS Slide 12 HDPE Slide 13 HIPS Slide 14 ABS Slide 15 HDPE Slide 16 Acrylic Acrylic Slide 17 THERMOPLASTICS - EVALUATION QUESTIONS: 1) What are thermoplastics? 2 ) Why do we use them? 3 ) When wouldnt we use them? 4) identify one example of: HIPS Acrylic HDPS ABS and give reasons why it is used.