Addition and Condensation Polymers: Structures, Properties, Uses & Reactions

What is the structure of LDPE?

[-CH₂-CH₂-]ₙ with highly branched chains.

What are the properties of LDPE?

soft and flexible due to branching

What is a common use of LDPE?

Squeeze bottles due to flexible walls.

What is the structure of HDPE?

[-CH₂-CH₂-]ₙ with mostly linear chains and little branching.

What are the properties of HDPE?

Denser, stronger, more rigid, and has a higher melting point than LDPE.

What is a common use of HDPE?

Rubbish bins as its rigid and durable

What is the structure of PVC?

[-CH₂-CHCl-]ₙ with polar C-Cl bonds that produce dipole-dipole attractions.

What are the properties of unplasticised PVC?

Rigid and durable; adding plasticisers makes it softer and more flexible.

What is a common use of unplasticised PVC?

Rigid water pipes.

What is the structure of polystyrene (PS)?

[-CH₂-CH(C₆H₅)-]ₙ with bulky benzene side groups.

What are the properties of solid polystyrene?

Rigid and brittle

What is a common use of solid polystyrene?

Rigid CD cases.

What is the structure of PTFE (Teflon)?

[-CF₂-CF₂-]ₙ with fluorine atoms surrounding the carbon backbone.

What are the properties of PTFE?

• High melting point, -

• unreactive, and

• non-stick.

What is a common use of PTFE?

Non-stick frying-pan coating.

What is the structure of Nylon 6,6? just say what links

[-NH-(CH₂)₆-NH-C(=O)-(CH₂)₄-C(=O)-]ₙ with amide links. (condensation)

What are the properties of Nylon 6,6?

• High tensile strength

• high melting point due to hydrogen bonding.

What is a common use of Nylon 6,6?

Ropes due to its high tensile strength.

What is the structure of PET (polyester)? Just say what links it has

[-O-CH₂-CH₂-O-C(=O)-C₆H₄-C(=O)-]ₙ with polar ester links. (condensation)

What are the properties of PET?

Strong and lightweight

What is a common use of PET?

Soft-drink bottles.

What is addition polymerization?

Unsaturated monomers join by reaction of their C=C bonds without eliminating small molecules.

What is condensation polymerization?

Monomers with suitable functional groups join, eliminating a small molecule like water.

What is the difference between crystalline and amorphous regions in polymers?

• Crystalline is regularly arranged, closely packed;

• amorphous lack order.

What is the effect of plasticisers on polymers?

They reduce effective interchain attractions and increase flexibility.

What is vulcanisation?

Heating rubber with sulfur to form covalent cross-links, improving strength and elasticity.