Polyethylene (PE) and polypropylene (PP) are both widely used polymers in the plastic and rubber industry. These two have similarities and common features. Long life, high quality, flexibility can be mentioned among these commonalities. Also, these two polymers are thermoplastic and semi-crystalline polyolefins that produce oily liquids when combined with other materials. But PE and PP also have differences, the most important of which is in their monomer unit, which is polyethylene monomer unit, ethylene and polypropylene monomer unit, propylene. But apart from the monomer unit, these two have other differences with each other that make polyethylene and polypropylene separate. Among these differences, the following can be mentioned:
1- Impact resistance and physical properties of polyethylene are such that it is more stable against cold. On the other hand, polypropylene has high fatigue resistance. In other words, polypropylene is usually used at temperatures above zero degrees Celsius due to its properties of bending, softening to heat and resistance to impact, and this is the most important difference between polyethylene and polypropylene.
2- Polypropylene is made from the combination of propylene monomers and polyethylene from the combination of ethylene monomers.
3- The static charge of polyethylene is lower than polypropylene and it is a good electrical insulator.
4- The melting point of polypropylene is higher than that of polyethylene, and they are used in the production of structural plastics and fibers.
5- The resistance to UV light of polyethylene is higher than that of polypropylene.
6- The chemical formula based on which polypropylene is produced is (C3H6)n and the chemical formula of polyethylene is (C2H4). The presence of a nucleating agent will be effective, while in polyethylene, due to the high speed of crystallization, the presence of nucleating agents is less effective. Therefore, it is more possible to produce a transparent product in polypropylene.
8- The printability of polypropylene films is more than that of polyethylene, and in polyethylene films, printability is possible only if the surface is modified.
9- Polyethylene is the first product used in the world. And polypropylene is the second plastic product.
10- The use of polyethylene is usually 100% pure, but polypropylene is generally copolymerized with polyethylene. It means that pure polypropylene has no tensile properties and is generally stiffer than polyethylene.
11- The chemical resistance of polypropylene against organic solvents, acids and electrolytes is much higher than that of polyethylene.
12- Polyethylene has physical characteristics that allow it to be used in Low temperatures can be used. Of course, polypropylene does not have this ability and should be used at higher temperatures.
13- The resistance to cracking of polypropylene is low, but polyethylene is somewhat elastic and has more flexibility.
br>14- Polypropylene is harder than polyethylene and is more useful for producing molded parts.
15- Polyethylene is a good electrical insulator, but it is easily electrostatically charged, which can be reduced by adding graphite, black carbon or anti-static agents. On the other hand, polypropylene is a bad electrical insulator compared to polyethylene.
16- The weight of polypropylene is lighter compared to polyethylene.
17- The price of polypropylene is much lower than the price of polyethylene.
18- Polypropylene is mostly used in automobile and packaging industries, hinges, household furniture and toys, carpets, Fibers, caps, synthetic papers, etc. are used, and polyethylene is used in plastic bags, food containers, bottles, films, food boxes, etc.
