Types of Plastic (Cambridge International IGCSE Environmental Management)

Types of plastic

• Plastics are long-lasting synthetic materials used in packaging, industry and everyday products

• Their environmental impact depends on:

  • What they are made from
  • How they break down

• Different types of plastics behave differently in soil, water and other ecosystems

Conventional plastics

• Conventional plastics—plastics made from fossil fuels, such as crude oil or natural gas

• These plastics are generally non-biodegradable

• They do not decompose naturally within a short time

• They break into smaller fragments rather than fully decomposing

  • They can take hundreds to thousands of years to break down into smaller fragments

Bioplastics

• Bioplastics—plastics made fully or partly from biological raw materials

  • Sources include plant starch, vegetable oils or algae

• Bioplastics can be biodegradable or non-biodegradable, depending on their chemical structure

  • Not all plant-based plastics decompose naturally

• They are designed to reduce reliance on fossil fuels

• Their environmental benefit also depends on how they are disposed of

Biodegradable plastics

• Biodegradable plastics—plastics designed to decompose in water or soil

• Breakdown occurs through natural processes

• They can be decomposed by bacteria and fungi

  • Microorganisms help break chemical bonds in the plastic

• Decomposition rate varies with biotic factors microbial activity

  • High microbial activity increases breakdown

• Decomposition also depends on abiotic factors such as temperature, moisture and oxygen levels

  • Warmer, wetter conditions encourage microbial activity and therefore speed up biodegradation

Non-biodegradable plastics

• Non-biodegradable plastics—plastics that do not decompose quickly

  • Break down over very long periods (hundreds to thousands of years) through physical processes like sunlight degradation or wave action

• These plastics often accumulate in landfills, oceans and coastal environments

  • They contribute heavily to long-term plastic pollution

Microplastics

• Microplastics—plastic fragments less than 5 mm in length

• Can be invisible to the naked eye

• Formed when larger plastics break down over time

  • These fragments spread easily through water and soil

• They are also manufactured for use in commercial products

  • Examples include microbeads in cosmetics or cleaning products

Exam Hint Students often assume all bioplastics are biodegradable. You need to know that some bioplastics do not decompose naturally.