Polypropylene is a flexible plastic made from the monomer (H2C=CHCH3).  Polypropylene has excellent UV and chemical resistance, making it the ideal choice for applications where the liner will not be buried.  A reinforcing scrim gives polypropylene additional tensile strength.  The scrim is a net made from polyester fibers with 9 threads per square inch.  Polypropylene is seamed with heat welds because it is almost chemically inert.  Projects requiring more than a single panel should be installed by a professional crew.