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REVISION CARDS - THERMOPLASTICS

 

V. Ryan 2013

 

 

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WHAT ARE THERMOPLASTICS ?

These plastics can be re-heated and re-shaped in various ways. They become mouldable after reheating as they do not undergo significant chemical change. Reheating and shaping can be repeated. The bond between the molecules is weak and becomes weaker when reheated, allowing reshaping. These types of plastics can be recycled.

By V.Ryan
  THERMOPLASTICS 1

Acrylic. (Known also as PERSPEX) This is the most common plastic in a school workshop. Purchased in the form of sheets and comes in a range of colours. It can be translucent (e.g. smoked), transparent or opaque. It is resistant to most acids and weather conditions. Easy to cut shape. Polishes well.

Baths, safety glasses, signs.

By V.Ryan
     

THERMOPLASTICS 2

LDPE - Low Density Polythene is tough and flexible. Softer than HDPE.

Can be moulded into almost any form. Flexible, comes in range of colours.
Bottles and plastic bags are made from the low density polystyrene.

By V.Ryan
  THERMOPLASTICS 3

HDPE - High Density Polythene which is rigid and hard. Less flexible than LDPE.

Machine parts, bowls and crates are generally made from high density polystyrene.

Can be moulded into almost any form. Flexible, comes in range of colours.

By V.Ryan
 
 
 

THERMOPLASTICS 4

Polypropylene (PP) is a thermoplastic often formed into products through injection and blow moulding.
It is robust, strong, flexible and supplied in a range of colours.
Food containers, chairs, packaging and storage units.

By V.Ryan
 
THERMOPLASTICS 5


Polyvinyl Chloride. Better known as PVC. A tough material, purchased as either a hard (inflexible) material or alternatively a flexible form. It can be extruded, welded or bonded with an adhesive. Range of uses including water pipes, raincoats, long play records, coating on electrical wires and packaging.

By V.Ryan
     

THERMOPLASTICS 6

Nylon. Is used in engineering to make gears and bearings. It’s oily nature means that friction is reduced between moving parts made from nylon.

Gears, bearings, wheels and clothing.

By V.Ryan
  THERMOPLASTICS 7

High Impact Polystyrene (HIPS).
Light material and yet strong. Available in a range of colours. Can be vacuum formed. Thinner HIPS is quite flexible.

Used for electrical casings, packaging, trays

By V.Ryan
 
 
 
QUESTIONS
 
1. Complete the paragraph on thermoplastics, by adding the missing words.
 
re-shaped  -  reheating  -  chemical  -  becomes weaker  -  recycled
 
These plastics can be re-heated and ___-_______in various ways. They become mouldable after __________ as they do not undergo significant _________ change. Reheating and shaping can be repeated. The bond between the molecules is weak and ________ _______ when reheated, allowing reshaping. These types of plastics can be _________.
 
2. Acrylic, aslo known as perspex is used widely in schools. Why is this?
 
 
 
3. What is the difference between LDPE Low Density Polythene and HDPE High Density Polythene?
 
 
 
 
4. What is the name of the main industrial process, through which Polypropylene (PP) is processed into products?
 
 
5. Name four products that are often manufactured from Polypropylene (PP). 
 
 
 
 
6. Write the full name of the material also called PVC.
 
 
 
 
7. Describe some of the physical properties of PVC
 
 
 
8. Why is Nylon often used in engineering?
 
 
 
9. Give the full name of HIPS and name one product manufactured from HIPS
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