Polyethylene

Polyethylene or polythene 

Is the most common plastic. As of 2017, over 100 million tones of polyethylene resins are produced annually, Polythene are divided mainly into two types:-

(1). Low density polyethylene.
(2). High density polyethylene.

Low density polyethylene are manufactured with high pressure (1000-5000 atm), high temperature (520 Kelvin); whereas High density polyethylene are manufactured with low pressure (6-7 atm), low temperature (.333-343 Kelvin).

Polypropylene

Polypropylene (PP)

 also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene is the second-most widely produced commodity plastic (after polyethylene).