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Rubber (Elastomer)

Overview

Rubber is an elastomer, a type of polymer known for its elasticity, flexibility, and ability to return to its original shape after deformation. In A Level Product Design, rubber is studied to understand elastic behaviour, shock absorption, grip, and sealing, rather than strength or rigidity.

Rubber can be: - Natural rubber - Synthetic rubber

Classification

  • Polymer type: Elastomer
  • Thermoplastic / Thermoset: Neither (elastomers form cross‑links during vulcanisation)
  • Recyclable: Limited (depends on type and additives)

Types of Rubber

Natural Rubber (NR)

  • Made from latex sap of rubber trees
  • Renewable resource
  • Excellent elasticity

Examples: rubber bands, tyres (partly), gloves

Synthetic Rubber

Made from oil‑based polymers. Common types include: - Neoprene - Styrene‑Butadiene Rubber (SBR) - Nitrile rubber

Examples: car tyres, seals, hoses, wetsuits

Physical Properties

  • Opaque
  • Dull or matt surface finish
  • Flexible and stretchy
  • Waterproof
  • Good grip (high friction)
  • Electrical insulator

Mechanical Properties

Property Description
Elasticity Excellent
Flexibility Very high
Toughness Good
Hardness Low
Impact resistance Excellent
Wear resistance Good (varies by type)

Working Properties

Advantages

  • Can stretch and return to original shape
  • Excellent shock absorption
  • Provides grip and friction
  • Good sealing properties
  • Resistant to water
  • Can be moulded into complex shapes

Disadvantages

  • Degrades under UV light
  • Can perish or crack with age
  • Limited temperature resistance
  • Some types affected by oils and chemicals
  • Difficult to recycle

Manufacturing Processes

  • Compression moulding
  • Injection moulding
  • Extrusion
  • Calendaring
  • Vulcanisation (adds sulphur and heat to improve strength and elasticity)

Vulcanisation

Vulcanisation is a key process in rubber production.

What it does:

  • Adds sulphur
  • Creates cross‑links between polymer chains
  • Improves:
  • Strength
  • Elasticity
  • Durability
  • Heat resistance

Typical Uses

  • Tyres
  • Seals and gaskets
  • O‑rings
  • Shoe soles
  • Rubber bands
  • Hoses and tubing
  • Shock absorbers
  • Mats and grips
  • Electrical insulation

Sustainability and Environmental Impact

  • Natural rubber is renewable
  • Synthetic rubber is oil‑based
  • Rubber is difficult to recycle
  • Tyres are often:
  • Reused
  • Ground into rubber crumb
  • Long lifespan reduces replacement
  • Disposal can be environmentally damaging if not managed

Health and Safety

  • Latex (natural rubber) can cause allergic reactions
  • Rubber fumes during processing can be harmful
  • Hot moulds and materials cause burn risks
  • Safe practice includes:
  • PPE
  • Ventilation
  • Temperature control
  • COSHH awareness

Cost

  • Low to medium cost
  • Natural rubber price varies with supply
  • Synthetic rubbers offer consistent pricing
  • Cost depends on additives and performance requirements

Suitability for Product Design

Rubber is suitable for: - Products requiring flexibility - Shock‑absorbing components - Seals and gaskets - Grip surfaces - Waterproof products

Rubber is less suitable for: - Rigid structures - High‑temperature applications - Precision components - Load‑bearing products

Comparison with Other Polymers

  • Rubber vs Thermoplastics:
  • Rubber is elastic
  • Thermoplastics are rigid or semi‑flexible
  • Rubber vs Silicone:
  • Silicone handles higher temperatures
  • Rubber is cheaper and tougher

Exam Tips (A Level Product Design)

  • Identify rubber as an elastomer
  • Key properties to mention:
  • Elasticity
  • Flexibility
  • Shock absorption
  • Link:
  • Elasticity → seals and tyres
  • Grip → shoe soles
  • Mention:
  • Vulcanisation
  • Compare with:
  • Plastics (rigid)
  • Foams (lighter, less durable)
  • Use key terms: elastomer, vulcanisation, elasticity

Summary

Rubber is a flexible, elastic elastomer widely used for products requiring grip, sealing, and shock absorption. Through vulcanisation, rubber gains improved strength and durability, making it suitable for demanding applications such as tyres and seals. Although recycling is difficult, rubber’s performance and longevity make it an essential material in A Level Product Design, especially when studying elastic behaviour and material selection.