A special type of HDPE film that has the properties for film applications to food wrapping, carrier sacks and grocery bags and other materials is available. Ethylene is polymerized through a process that is catalytic and this is pumped out of the chamber where it is produced. These are then shipped off to manufacturers of HDPE films. This is made through a die where compressed air is blown up into a thin bubble of film. The types and properties of HDPE film can be studied online. HDPE granules can be bought in film grade or pellet by filling in the contact form on their website. They would surely get back to you.