Differentiate between rubbers and plastics on the basis of intermolecular forces.
Rubber is a natural polymer which possesses elastic properties. Natural polymer is a linear polymer of isoprene (2-methyl-1, 3-butadiene).
In natural rubber, m-polyisoprene molecules consist of various chains held together by weak van der Waals’ interaction and has a coiling structure. So, it can be stretched like a spring and it regains its original shape after the force is released.
Plastics are synthetic or semi-synthetic polymers of organic compounds which possess intermediate intermolecular forces of attraction. It has linear, structure that can be moulded but cannot regain its original shape after stretching is over.