Polyethylene Vs Polypropylene: When To Choose

1. What is polyethylene?

Polyethylene is a polymer composed of repeated ethylene monomer units (-CH2-CH2-) which are derived from petroleum or natural gas. It is available as:

Low-density polyethylene (LDPE) which is flexible and transparent.

High-density polyethylene (HDPE) which is a rigid polymer with a higher density compared to LDPE.

Linear low-density polyethylene (LLDPE) which is a flexible and tough form that combines the properties of LDPE and HDPE.

2. What is polypropylene?

Polypropylene is a polymer composed of repeated propylene monomer units (-CH2-CH(CH3)-) derived from petroleum. They are well known for their high strength & stiffness. It is mostly available as:

Homopolymer polypropylene which is made solely from propylene monomer units.

Random copolymer polypropylene which contains both propylene and ethylene or other alpha-olefin comonomer units.

Block copolymer polypropylene which consists of blocks of polypropylene and ethylene-propylene rubber.

 

3. Cost – Which polymer wins the budget battle?

The cost of both can vary on the basis of region, supplier, application, etc. Generally, PE is slightly more expensive than PP mostly because of its manufacturing.

The cost of HDPE ranges from $0.50 to $1.50 per pound. LDPE ranges from $0.30 to $0.70 per pound. LLDPE is in between the two, costing between $0.40 to $1.00 per pound.

Homopolymer polypropylene which is a more commonly used type is priced at around $0.30 to $0.35 per pound. Copolymer polypropylene costs around $0.35 to $0.40 per pound.

 

4. Processing Methods: From Raw to Finished Product

Processing of polyethylene

Most popular technique for polyethylene is injection molding. In this process, thermoplastic in molten form is injected into a mold under high pressure, then cooled to solidify it into the desired shape. With this method, complex parts for automotive components can be made.

It can also be processed via extrusion. This involves pushing molten polyethylene through a die to create a continuous shape, such as a tube or sheet. Pipes and films can be produced with this.

 

Processing of polypropylene

Polypropylene can be processed in similar fashion with the two techniques namely injection molding and extrusion. But one technique unique to PP is thermoforming. It involves heating a sheet of plastic until it becomes soft and pliable, and then shaping it over a mold using vacuum pressure. Food packaging trays and interiors for automotives can be produced this way.

PP requires higher processing temperatures and has a narrower processing window vs PE. It tends to have a higher shrinkage rate during cooling, which can affect the dimensional accuracy of molded parts.

 

5. Typical Applications: The Limitless Possibilities of PE vs PP

Industries served by polyethylene

It is a widely used thermoplastic owing to its low cost, excellent resistance to chemicals, and low density. Here are some known applications:

Packaging: Used in materials such as plastic bags, shrink wraps, and stretch films.

Pipes: Used in water supply and drainage systems due to chemical resistance and durability.

Automotive components: Used in fuel tanks, battery cases, etc., as it is tough

 

Industries served by polypropylene

Packaging: Used in food containers, bottle caps, and closures as it is tough.

Textiles: Used in carpets, upholstery, and geotextiles due to strength.

Automotive components: Used in bumpers, interior trim, and battery cases due to their resistance to chemicals.

 

6. About Us

Luoyang Dema Import & Export Co., Ltd. aims to provide high-quality, cost-effective products for global factories, plastic product manufacturers, and material distributors. Luoyang Dema Import & Export Co., Ltd. provides the best PP, PE, PVC, PET, EVA, ABS material solutions for plastic product manufacturers, wholesalers, distributors, distributors, factory owners, processing workshops, etc.

If you are looking for general plastic materials, please feel free to get the latest prices and quotations from Luoyang Dema Import & Export Co., Ltd. The sales team will reply within 48 hours.