High-Density Polyethylene Films
High density polyethylene or HDPE is a low cost, milky white, semi-translucent thermoplastic. It is flexible but more rigid and stronger than LDPE and has good impact strength and superior puncture resistance. Like LDPE, it also has good chemical resistance, good release properties, and good vapor but poor gas barrier and weathering properties. Other limitations or disadvantages include: subject to stress cracking, difficult to bond, flammable, and poor temperature capability.
Typically, high-density polyethylene is more linear and consequently more crystalline than LDPE. The higher crystallinity leads to a higher maximal service temperature up to about 130°C and results in somewhat better creep resistance. The lower service temperature is about -40°C.
HDPE tends to be stiffer than other polyethylene films, which is an important characteristic for packages that need to maintain their shape. HDPE is easy to process and can be blended with other polymers and/or additives, like (surface treated) fillers, other polyolefin (LDPE, LLDPE), and pigments to alter its basic properties.
HDPE film is often used in many of the same applications as LDPE and LLDPE and in some cases it is blended with LDPE to modify its properties. HDPE is well suited for applications where a greater tensile and compression strength is needed and/or when higher stiffness and rigidity is required. Like LDPE, HDPE possesses excellent impact strength and corrosion resistance.
Due to the low odor, high chemical resistance and inertness, many PE grades are suitable for packaging applications under FDA regulations. Due to the high boiling point, many grades can be sterilized in boiling water.
Typical HDPE film applications include bags; liners; food and nonfood packaging; agricultural and construction films.
In recent years, HDPE has gaining market share mainly because of its down-gauging properties, which allows for thinner films and packaging (i.e. less material is used) that deliver an equal performance.
HDPE films are typically 0.0005" to 0.030" thick. They are available in translucent or opaque colors. HDPE is also available with anti-static, flame retardant, and ultraviolet additives.