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Physical properties difference between PE and PP

May 19,2022

The main physical properties difference of PE( Polyethylene ) and PP(Polypropylene)
The physical properties of PE are as follow:

PE(polyethylene) is a kind of thermoplastic resin which is polymerized by ethylene. In industrial application, in also include the polymer of ethylene and a small amount of α-olefin. PE is odourless, non-toxic and feels like wax with characteristics of excellent low temperature resistance(the lowest working temperature can reach -100~-70°C), good chemical stability and resistance to most acid and alkali( not resistance to oxidizing acid). it doesn’t dissolve in common solvents with low moisture absorption and good insulativity
Polyethylene is crystalline thermoplastic resin. Its chemical structure, molecular weight, polymerized degree and other properties are largely dependent on polymerization methods. Polymerization methods decide it’s type and degree of branch chains. Crystalline degree is dependent on neat degree of molecular chain and thermal process
Polyethylene is sensitive to environment stress(chemical and mechanical effect ) and it’s heating aging property is inferior to polymer. PE can be processed by the forming methods of common thermoplastic. It’s application is extensive like film, package material, container, pipe, filament, cable and daily products and it can also be used as high frequency insulative material for television and radar
With the development of petrolchemical industry, polyethylene production has developed rapidly and its production accounts about 1/4 of total plastic production. It’s total production capacity reachs 150MT now. The tendency of PE production shows that its production and consumption are gradually turn to Asia region and China has become the most important market.

The physical properties of PP are as follow:

PP(Polypropylene) is a kind of thermoplastic resin which is polymerized of propylene. It is divided into isotactic polypropylene, atactic polypropylene and syndiotactic polypropylene according to methyl position
When methyl groups are arranged on the same side of the molecular main chain, it is called isotactic polypropylene. If methyl groups are arranged on both sides of the molecular main chain, it is called atactic polypropylene. When methyl groups are arranged alternately on both sides of the molecular main chain, it is called intertactic polypropylene. General industrial production of polypropylene resin, isotactic structure content of about 95%, the rest is random or intermetric polypropylene.
Industrial products are made of isotactic materials. Polypropylene also includes copolymers of propylene and a small amount of ethylene. Usually translucent colorless solid, odorless and non-toxic. Due to the regular structure and high crystallization, so the melting point can be as high as 167℃. Heat resistance, corrosion resistance, products can be used steam disinfection is its outstanding advantages. It is the lightest general-purpose plastic with low density. The disadvantage is low temperature impact resistance is poor, easy to aging, but can be overcome by modification respectively.
Copolymer PP material has a lower thermal deformation temperature (100℃), low transparency, low gloss, low rigidity, but has a stronger impact strength, the impact strength of PP increases with the increase of ethylene content. The veka softening temperature of PP is 150℃. The material has good surface stiffness and scratch resistance due to its high crystallinity. There is no environmental stress cracking problem in PP.

Jwell PE PP pipe extrusion line

Jwell PE PP sheet & plate extrusion line

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