3.4 - polymers Flashcards
what are polymers?
polymers are very large molecules composed of small repeating structural units, known as monomers.
what are addition polymers?
addition polymers can be synthesised from alkene monomers, it occurs when monomer molecules link without the loss of atoms.
explain the advantages of synthetic polymers.
strong and light weight, flexible, cost effective and the ability to resist corrosion.
explain the disadvantages of synthetic polymers.
- non-biodegradable, some contribute to the pollution of the earth.
- plastics constitute 22 to 29% of the volume of solid waste.
- in production, fumes contain toxic products such as carbon monoxide, carbon dioxide and sulphur dioxide.
what are thermoplastic polymers?
thermoplastic polymers are long chain polymers with minimal cross links characterised by exhibiting weak intermolecular forces between the individual polymer chains within the material.
- they can be heated and remoulded
- they are recyclable
what are thermosetting polymers?
thermosetting polymers are characterised by the presence of strong covalent bonds between individual polymer chains within the material. There is an increased amount of cross linking and hence they have greater strength and rigidity.
- the do not melt, they are durable, however they are not recyclable.
what is vulcanisation?
vulcanisation is a chemical reaction between sulphur and a natural rubber. It creates cross-links between the molecular chains in rubber, and they purpose is to harden the rubber so it does not melt or soften in cool temperatures.
