Flashcards in 13.5 - Polymerisation in Alkenes Deck (12)
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1
What is addition polymerisation?
Alkenes undergo addition polymerisation to produce long saturated alkanes which have high molecular masses.
2
What conditions are used for industrial polymerisation?
High temperature and pressure using catalysts.
3
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
4
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
5
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
6
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
7
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
8
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
9
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.
10
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.
11
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.
12
