Commodity Materials
The least expensive materials are also the easiest to process. Polyethylene (PE) and polypropylene (PP) are the most popular blow-molding resins. PE is currently less expensive but PP tends to be stiffer which sometimes offsets the cost difference.  These materials are resistant to most chemical attacks.  One difference is temperature performance with basic grades of PE performing well from -100 to +175 degrees F and PP performing well from -20 to +220 degrees F.  These materials usually perform according to this design guide.