AQA GCSE DT - Polymers

Core technical principles + specialist technical principles

What are the 2 types of polymers?

Thermosetting + thermoforming polymers

What is a thermoforming polymer?

= type of polymer that can be reheated and reshaped multiple times

What are the main properties of a thermoforming polymer? (Name 3)

• Recyclable

• Pliable (flexible & easy to bend)

• Good impact resistance

What are 4 examples of thermoforming polymers?

• Acrylic (PMMA)

• Polypropylene (PP)

• High Impact Polystyrene (HIPS)

• Polyethylene (PE)

What are thermosetting polymers?

= type of polymers that cannot be reshaped after heating and shaping it once

What are some properties of thermosetting polymers? (Name 4)

• Heat-resistant

• Electrical insulators

• Durable

• Brittle

What are 3 examples of thermosetting polymers?

• Epoxy resin

• Urea formaldehyde

• Melamine formaldehyde

What is the primary source of most polymers?

Crude oil

How is crude oil refined?

Through fractional distillation

Outline the 5 main steps of fractional distillation

1. Crude oil is heated until it becomes a vapour

2. Vapours rise up the distillation column

3. Column cools and different hydrocarbons condense at different temps

4. Seperated into different fractions & drawn off for further processing

What is cracking?

= breaking down large hydrocarbons into smaller ones used in polymer production (eg. Propylene)

What type of polymer is best suited for seating and why? (name 3 properties it must have)

Polypropylene:

• Flexibility - user can adjust in seat without breaking it

• Impact resistance - prevents damage from sudden force (sitting on it abruptly)

• Heat resistance - can withstand temp changes (outdoor use/exposure to sun)

What type of polymer is best suited for electrical fittings and why? (name 3 properties it must have)

Urea formaldehyde:

• Insulating properties - avoids risk of short circuits or shocks

• Rigidity - electrical components can maintain shape under stress & pressure

• Heat resistance - can withstand high temperatures from electrical components

What are polymer stabilisers & what are they used for?

= additives to prevent degradation & discolouration from UV sunlight exposure

When are polymer stabilisers commonly used?

Outdoor products - improves durability

What equipment can be used for cutting/drilling polymers?

• Saws

• Laser cutters

• Standard drill bits

What is polymer casting? + what type of polymer is it used for?

Liquid polymer poured into moulds - used for thermosetting polymers

What is polymer deforming?

= heating thermoforming polymers to reshape them (eg. Vacuum forming)

What is polymer welding? + what are the 3 main types?

= joining polymers through: heat welding, solvent welding, ultrasonic welding

Outline the process of injection moulding in 4 main steps

1. Granules held in a hopper

2. Granules are heated and melted along a heating chamber via Archimedean screw

3. Melted polymer pushed into mould with a hydraulic ram

4. Mould cools, polymer solidifies and product is ejected

Outline the process of extrusion in 4 main steps

1. Granules held in a hopper

2. Granules are heated and melted along a heating chamber via Archimedean screw

3. Melted polymer pushed through a die mould

4. After cooling in cooling chamber, extruded plastic is cut to desired length

Outline 3 surface finishes that can be applied to polymers

1. Vinyl decals = adhesive vinyl decals applied for custom designs/brand logos

2. Polishing = smooths & enhances gloss of (mainly) thermoforming polymers

3. Printing = adding decorative/informational text - methods eg. screen printing, laser printing

What are 2 environmental issues caused by using polymers?

• Most are non-biodegradable → disposal contributes to pollution

• Fractional distillation & cracking are very energy extensive → high CO2 emissions

What are 2 challenges to consider when recycling polymers?

• Contamination: If polymers aren’t sorted/cleaned properly → affects quality of recycled material

• Downcycling: Recycled polymers often have inferior properties compared to virgin plastics → leading to lower-quality products

What are some alternatives to traditional polymers?

• Bioplastics: Made from renewable sources such as plant materials instead of fossil fuels.

• Plant based polymers: such as PHA

What are 3 ways to reduce polymer use?

• Design for the Environment: designing products that use less material & can be recycled

• Longevity and Reusability: Creating durable products that can be reused

• Legislation: introducing plastic bans (e.g., banning single-use plastic bags or straws)