U.S. Plastic Corp.® is your tank source for polypropylene tanks. Polypropylene tanks are made of polypropylene, a polyolefin which is a thermoplastic made by the polymerization of propylene gas. Polypropylene offers a good balance of thermal, chemical and electrical properties with moderate strength. Polypropylene possesses a good strength to weight ratio. Because it has such a hard, high gloss surface, polypropylene is ideally suited to environments where there is concern for bacteria build up that can interfere with flow.