Flashcards in 13.5 - Polymerisation in Alkenes Deck (12)
What is addition polymerisation?
Alkenes undergo addition polymerisation to produce long saturated alkanes which have high molecular masses.
What conditions are used for industrial polymerisation?
High temperature and pressure using catalysts.
What are the benefits of polymers?
- Cheap and readily available
- More convenient than glass, metal dustbins, paper bags
- Lack of reactivity - good for storing foods and chemicals safely
Name one drawback with regards to polymer disposal?
Lack of reactivity also means that they are difficult to dispose of, they are mostly non-biodegradable
What are the benefits of recycling polymers?
- Reduces environmental impact - no need to burn fossil fuels
- Decreases landfill amount
- Discarded polymers must categorised by type (if poylmers are mixed it renders the recycling process useless)
- Polymers are made into flakes, washed and dried to be melted and reconstructed for use again
What are the drawbacks of recycling PVC?
Can't be burnt as the high chlorine content in PVC and the range of additives make it toxic (releases hydrogen chloride a corrosive gas)
- Nowadays solvents are added to PVC to dissolve the polymer, high grade PVC is recovered in precipitation from solvent, solvent is used again
What use can polymers take if they cannot be recycled?
Since some polymers are derived from natural gases or petroleum, they have high stored energy value
- They can be incinerated to produce heat > generate steam for turbines to produce electricity
What is feedstock recycling?
- Reclaiming monomers, gases or oils from waste polymers.
- Products of FR resemble those from crude oil refineries
- FR can handle unsorted and unwashed polymers
- Products can be used as raw materials for new polymer production
What are bioplastics?
Made from plant starch, cellulose, plant oils
- They are a sustainable alternative to oil-based products
Bioplastic use protects our environments and conserves oil stores.
How do biodegradable polymers work?
- Decomposed by microorganisms to form water, CO2 and biological compounds
- Biodegradable polymers usually made from starch or cellulose to allow microorganisms to break them down.
What are advantages of biodegradable polymers?
- They live no visible or toxic residues
- Supermarket bags or bin liners can be composted with the rubbish
- New products such as compostable plates, cutlery etc. mean there will be less waste plastic.