Marlex is a trademarked name for crystalline polypropylene and high-density polyethylene (HDPE). These plastics were invented by J. Paul Hogan and Robert Banks, two research chemists at the Phillips Petroleum company.
Marlex was used by Wham-O for their Hula Hoops in the 1950s, which helped create a market for this plastic. It is now used surgically as a reinforcing mesh in inguinal hernia repair.
References
Marlex Wikipedia(Text) CC BY-SA