Plastics & their Disposal
Section: 11. Organic Chemistry | Syllabus: Cambridge AS Level Physics 9702
Plastics & their Disposal Plastics are synthetic polymers that have become essential materials in modern life. However, their widespread use has created significant environmental challenges related to disposal and waste management.
Plastic A synthetic polymer that can be molded into shape when hot and retains that shape when cooled. Image Placeholder [INFOGRAPHIC: Timeline showing plastic production growth from 1950s to present, with images of everyday plastic items and statistics on global plastic production] Types of Plastics Thermoplastics Thermoplastic A plastic that softens when heated and can be remolded into new shapes.
It can be heated and reshaped multiple times. Structure: Long polymer chains with weak intermolecular forces between them No (or few) cross-links between chains Chains can slide past each other when heated Properties: Soften when heated Can be remolded and recycled Generally flexible Lower melting points Examples: Poly(ethene) - PE Poly(propene) - PP Poly(chloroethene) - PVC Poly(styrene) - PS Nylon Polyester (PET) Thermosetting Plastics (Thermosets) Thermosetting Plastic A plastic that sets hard when first heated and molded, but cannot be softened or remolded by further heating.
Structure: Polymer chains with many strong covalent cross-links Forms a rigid 3D network structure Cross-links prevent chains from sliding Properties: Do not soften when heated Cannot be remolded once set Rigid and hard High melting points Char and decompose rather than melt Examples: Bakelite - electrical switches, saucepan handles Melamine resin - worktops, plates, adhesives Epoxy resins - adhesives, boat building Polyurethane - foam cushions, insulation Diagram Placeholder [COMPARISON DIAGRAM: Two side-by-side illustrations: Left: Thermoplastic structure - linear chains with few cross-links, arrows showing chains sliding when heated Right: Thermosetting structure - heavily cross-linked 3D network, showing rigid structure that can't move when heated Use different colors for polymer chains and cross-links] Comparing Thermoplastics and Thermosets Property Thermoplastics Thermosetting Plastics Structure Separate polymer chains, weak forces between them Cross-linked 3D network Cross-linking None or very few Many strong covalent cross-links Effect of heating Softens and can be remolded Does not soften, chars/decomposes Can be recycled?
YES - can be melted and remolded NO - cannot be remolded Flexibility Generally flexible Rigid and hard Strength Moderate Very strong Examples Polyethene, PVC, nylon, polyester Bakelite, melamine, epoxy resins Uses Bottles, bags, packaging, pipes Electrical fittings, saucepan handles, worktops Environmental Issues with Plastics Problems Non-biodegradable - most plastics don't break down naturally, persist for hundreds of years Landfill waste - takes up valuable space, doesn't decompose Marine pollution - plastic waste in oceans kills marine life, enters food chain Microplastics - tiny plastic particles contaminate water, soil, and organisms Made from crude oil - uses non-renewable fossil fuel resources Toxic fumes when burned - incomplete combustion produces harmful gases Litter and visual pollution - spoils natural environments Wildlife hazards - animals can get trapped or ingest plastic Carbon footprint - production and disposal release greenhouse gases Image Placeholder [PHOTO GALLERY: Environmental impact images: - Plastic pollution in ocean with marine life - Landfill site filled with plastic waste - Beach covered in plastic litter - Microscope image of microplastics - Wildlife affected by plastic (turtle with plastic bag, bird with plastic in stomach) Include statistics overlay showing persistence times for different plastics] Great Pacific Garbage Patch Massive area of floating plastic debris in Pacific Ocean Estimated to be 1.6 million km² (twice the size of Texas) Contains approximately 80,000 tonnes of plastic Formed by ocean currents concentrating plastic waste Harms marine ecosystems and enters food chain Interactive Placeholder [INTERACTIVE MAP: World map showing ocean plastic pollution hotspots, including the Great Pacific Garbage Patch.
Click on regions to see: - Amount of plastic waste - Types of plastic most common - Species affected - Cleanup initiatives] Methods of Plastic Disposal 1. Landfill Process: Waste plastic buried in designated sites Compacted and covered with soil Advantages: Cheap and simple method Can handle large volumes of waste Prevents litter and visual pollution Disadvantages: Takes up valuable land space Plastics don't decompose - waste of resources Potential for toxic chemicals to leach into groundwater Methane gas production from decomposing organic waste Land cannot be used for other purposes for many years Unsightly and may attract pests 2.
Incineration (Burning) Process: Plastics burned at high temperatures (>850°C) Heat energy can be recovered for electricity generation Reduces volume of waste by ~90% Advantages: Reduces volume of waste…
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