Polymers

Question 1

How are natural plastics formed ?

Answer 1

Natural latex is harvested by tapping a tree. This can be mixed with other things to form resins, rubbers and plastics.

Question 2

What are Bioplastics made from?

Answer 2

Made from the starch of corn or vegetables

Question 3

What are Synthetic plastics made from?

Answer 3

Made from finite petrochemical resources such as crude oil

Question 4

How are polymers produced?

Answer 4

Crude oil is mined and then refined in fractional distillation, which separates the chemicals into fractions. These fractions are split into monomers which mix with chemicals to become polymers

Question 5

Describe Fractional distillation

Answer 5

Crude oil is heated to 350 degrees then pumped into the base of the distillation tower. Crude oil vaporises and rises up the tower. As they reach there melting points the different substances of the crude oil condense. The heaviest, hardest to break molecules at bottom, lightest and easiest at top. The fractions are then siphoned off for cracking.

Question 6

What is a Thermoforming polymer?

Answer 6

Have long chains of molecules tangled together with no mixed structure or pattern. Generally soft and flexible with shape memory.

Question 7

What is a Thermosetting polymer?

Answer 7

More brittle than thermoplastics and are best suited to stiffer mouldings. They also have long chains of molecules, cross-linked to form a rigid molecular structure. Very hard and waterproof when solid

Question 8

What is PETE

Answer 8

Polyethylene terephthalate - Clear, easily coloured, smooth finish (Plastic bottles)

Question 9

What is HDPE

Answer 9

High density polyethylene - Flexible, translucent, weatherproof, tough (Hard hats)

Question 10

What is PVC

Answer 10

Polyvinyl Chloride - Durable, tensile strength, low water absorption, chemical and flame resistance (Piping)

Question 11

What is LDPE

Answer 11

Low density polyethylene - Tough, impact-resistant, low temp impact resistance, good chemical resistance (Water buoys)

Question 12

What is PP

Answer 12

Polypropylene - Translucent, easily coloured, tough, good chemical and fatigue resistance (Lunch boxes)

Question 13

What is PS

Answer 13

Polystyrene - Low cost, easy to make, easy to shape (Yoghurt pots)

Question 14

Name the primary Stock forms

Answer 14

Sheets, Rods, Tubing

Question 15

How are Plastic films used?

Answer 15

Used in packaging, especially in food industry. Heat sealed to be airtight and tamper proof.

Question 16

What is the Gauge of a plastic

Answer 16

The wall thickness of a plastic

Question 17

What is Expanded polystyrene used for?

Answer 17

EPS is used regularly as thermal insulation and food packaging.

Question 18

What are Powders and Granules used for

Answer 18

Mainly used in plastic processing, the granules are heated into a liquid and then reformed.

Question 19

What are the uses of Plastic Additives

Answer 19

Can adapt the platsic for different uses by adding chemicals, additives and compounds during manufacturing.

Question 20

How are Tailored Plastics changed for use

Answer 20

Pigments and plasticises can be added to change the colour, flexibility or scent of a plastic

Question 21

What are the uses of Thermoplastics

Answer 21

Can be woven into fabrics to make them more resistant to wear and tear.

Question 22

How does 3D Printing (Laser Sintering) work

Answer 22

Uses as laser source to provide thermal energy and selectively fuse together particles of a powdered material. More expensive and precise

Question 23

How does 3D Printing (Fused Deposition) Modelling) work

Answer 23

Extrudes a thermoplastic filament in a series of layers over a build plate. Cheaper and often used in schools

Question 24

How does Chemical Welding work

Answer 24

A chemical liquid is placed between two pieces of something which then causes a chemical reaction, forcing the tiles to fuse together.

Question 25

What are the advantages of Laser Cutting

Answer 25

A very accurate way to cut different types of thermoforming polymer sheets. Can follow an uploaded design to a very fine tolerance.

Question 26

What is Kerf Allowance

Answer 26

What the laser removes when cutting

Question 27

Explain the process of Injection Moulding

Answer 27

1. Pellets and Granules are fed into a hopper 2. Hopper feeds an Archimedes screw which drags the granules to a heater where they melt 3. Melted plastic falls into the mould 4. Injection cylinder fills and seals the mould 5. Plastic cools in the mould and the moving plate is removed, leaving the moulded object

Question 28

Explain the process of Extrusion Moulding

Answer 28

1. Pellets and Granules are fed into a hopper 2. Continuous flow of molten plastic is forced under pressure and through a die (mould). 3.Long continuous strips same shape as exit hole is created 4. Passed through a water tank and pull rollers to cool and solidify it

Question 29

Explain the process of Blow Moulding

Answer 29

1. A tube of heated and softened plastic is inserted into a solid mould with the mould gripping the parrison 2. Air is then injected which forces the plastic to expand into the shape of the mould 3. Mould is opened and finished project is trimmed

Question 30

What is Rotational Moulding

Answer 30

Makes hollow shapes with uniform wall thickness Powder is put in a mould and heated and rotated and then cooled while still rotating

Question 31

Reasons for Surface Treatments and Finishes

Answer 31

Protection Aesthetics Functionality

Question 32

Why are Spray Primer and Paints used?

Answer 32

Plastics are primed and sprayed with paints for aesthetics and protection from UV degradation. They are quick to apply but contain VOCs (Volatile Organic Compounds) which release hazardous fumes.

Question 33

What are Vinyl Decals

Answer 33

Printed and cut self-adhesive vinyl can be attached to most surfaces. They are easy to make and use in projects if you have access to vinyl sticker machine and a CAD programme.

Question 34

What is Flocking

Answer 34

When flocking fibres are bonded to statically charged materials with an adhesive

Question 35

Wha are the uses of Etching and Frosting

Answer 35

Patterns or grooves can be etched into surfaces to make light reflect more effectively or the material can be frosted across large areas to make the plastic more opaque

Question 36

What is Heat transfer printing

Answer 36

An image is printed onto special papers and bonded onto the surface of an object with a heat press. This is commonly used for t-shirts and mugs

Question 37

What is Electroplating

Answer 37

Plastics are covered in a conductive layer or etched before plating. This is mainly used in the car industry

Question 38

What are Rubberising sprays

Answer 38

A slightly textured coating with a matt finish. Sprayed onto various materials to provide grip

Question 39

Why is Polishing used

Answer 39

Polishing is used to restore a high quality finish if the plastic becomes rough or scratched during the process

Question 40

What is Hydrographic printing

Answer 40

Colour images are printed onto a water soluble film which floats in a tank. The object is then dipped in the tank and is coated by the film which contains an adhesive