Impact strength describes how well a film can withstand a sudden, concentrated load without puncturing or bursting. A full bag being set down on the floor, or a sharp-cornered product inside it striking the film, are everyday situations in which impact strength is put to the test.
In the laboratory, this property is usually measured by dropping a weight onto the film from a set height. The choice of raw material clearly affects the result; LLDPE and some blends give the film higher impact strength. Film thickness, layer structure and production conditions also play a part. This property is especially important in products such as garbage bags and courier bags.