Polymers are giant structures made of many repeating units called monomers
The properties of polymers depend on what they are made of and by which method they are made..
High and low densities of polymer are made using different reaction conditions and catalysts.
Thermosoftening These plastics are flexible and melt when heated because there are weak intermolecular forces between the polymer chains so they can slide over each other easily.
Thermosetting These plastic are rigid and do not melt when heated because there are strong intermolecular forces (cross links)between the polymer chains