A level revision

Polymers

Polymers are made up of long chain molecules, much like a can of worms. This construction explains their properties

Structure of a polymer: Long chain molecules 'tangled' together

Structure of a stretched polymer: Long chain molecules stretch becoming straight and parallel

Conductivity

Polymers are poor conductors (insulators) because of a lack of free electrons. Electrons are not free to move because of the bonds in the molecules.

Elasticity

Polymers like rubber are elastic because the long chain molecules are allowed to stretch and become parallel. When the stress is released they return to their original state. Like other materials some polymers are only elastic up to point - their elastic limit. This reached when the bonds in the molecules break.

Stiffness

Polymers are stiff because the long chains are often linked together backing them hard to break.