Polypropylene is economical and offers an excellent combination of physical, chemical, mechanical, thermal, and electrical properties that are not found in any other thermoplastic. Though lower in impact strength than polyethylene, PP has superior working temperature and tensile strength.
LLDPE (Linear Low Density Polyethylene) has a density range of 0.9150.925 g/cm3. LLDPE replaces its predecessor Low Density Polyethylene (LDPE) in many applications. LLDPE is a linear polymer with a number of short branches, made by copolymerization of ethylene with short-chain alpha-olefins. (for example, 1-butene, 1-hexene and 1-octene). LLDPE has higher tensile strength, impact and puncture resistance than LDPE. Globally, over 80% of LLDPE is used in film applications such as food and non-food packaging, shrink / stretch film, and non-packaging uses. Major growth areas are high clarity packaging, high barrier thin films and active packaging that increases shelf life and enhances flavor.
High Density, (0.95-0.965 g/cm3) Polyethylene, has higher temperature resistance, stiffness, and superior water vapor barrier properties when compared to LLDPE. HDPE has a low degree of branching, hence stronger intermolecular forces and tensile strength. HDPE is highly preferred as a sheathing material where it provides high resistance to water penetration. It is very hard, has low coefficient of friction, and is abrasion resistant. Hence, it is used in products and packaging such as milk jugs, detergent bottles, margarine tubs, garbage containers and water pipes.