Polyethylene / Polyproplene Information

PolyEthylene (PE) and PolyPropylene (PP) are the two most common materials used for the manufacture of flexible packaging products. Both these materials are collectively referred to as "Poly". Polyethylene (PE) and Polypropylene (PP) films are manufactured into "poly bag" products.

Polyethylene:  A lightweight thermoplastic used especially in packaging. Polyethylene (PE) molecules have two hydrogen atoms attached to each carbon atom in a chain. This structure gives polyethylene it's tough, flexible and chemical resistant characteristics.

Common forms of polyethylene used in making plastic bags include:

Low Density Polyethylene (LDPE) is the most commonly used material for flexible packaging because it is tough, transparent and electrically stable.  Low Density Polyethylene (LDPE) also has a low melting point, which is required for heat sealing applications. When low density polyethylene bags (LDPE) are made with virgin (no additives) polyethylene resin, they meet FDA standards for use with food products.

Linear Low Density Polyethylene (LLDPE) A given thickness of Linear Low Density Polyethylene (LLDPE) is significantly stronger than the same thickness of Low Density Polyethylene (LDPE). Therefore, Linear Low Density Polyethylene (LLDPE) can be thinner and lighter and perform the same job as LDPE.  These bags are bottom sealed for added strength.  Linear Low Density Polyethylene (LLDPE) also has a low melting point, which is required for heat sealing applications.

High Density Polyethylene (HDPE) is used because of its excellent strength and significantly light weight.  It has excellent protection capability and it is used in grocery and other retail segments extensively, while also suitable for a myriad of other uses.

Metalocene is a catalyst agent that creates a polyethylene structure with greater clarity and strength.  Bags are made using metalocene and the additive EVA to enhance their elasticity and strength at lower temperatures.  Due to these unique properties, Metalocene bags are well suited for storing and transporting ice.

Nylon Laminated Polyethylene Vacuum packaging is the process of removing the air from within an impermeable plastic package and sealing food items inside to maintain flavor, freshness and color.  Some forms of harmful bacteria thrive in the presence of oxygen.  A Nylon film is incorporated into vacuum bags to prevent oxygen from returning to the bag after the extraction process, and prevents bacteria from spoiling the contents.  Nylon vacuum bags can be used to preserve many different types of food, including beef, lamb, chicken, fish and cheese.

Polypropylene (PP): Polypropylene has excellent chemical resistance is strong and has the lowest density of the plastics used in packaging.  It has a high melting point, making it ideal for hot-fill liquids.  In film form it may or may not be oriented (stretched). Polypropylene is found in everything from flexible and rigid packaging to fibers and large molded parts for automotive and consumer products. (Adapted from Modern Plastics Encyclopedia 1995; Plastic Packaging Opportunities and Challenges, February 1992).

Polypropylene (PP) is a strong, stiff thermoplastic with excellent chemical resistance and a high melting point.  It is stiffer and clearer than polyethylene and has excellent resistance to water, salt and acid solutions and, when manufactured with virgin resin, polypropylene (PP) meets FDA requirements for food applications.  Polypropylene (PP) is exceptionally suited to maximize visual appeal of food and display products. Any product that needs an outstanding professional appearance can benefit from polypropylene (PP) packaging.