Polyethylene films are found in a wide variety of applications. Some examples include: grocery bags, food packaging, industrial shrink wrap, and agricultural films. And a variety of specific polyethylene products are employed to make these films depending upon the physical properties required in the film: high density, low density, linear low density and other forms of PE are used in films. Also, PE films might be made in multi-layers where polymers known as nylon or EVOH might be used to increase gas barrier and/or strength of the film.
From this page you can access the APR DesignTM Guidelines specific for PE Films.