A fluid pumping mechanism in one embodiment includes a fluid reservoir, and a multiple layer film extending over a portion of the fluid reservoir, wherein fluid is moved through the reservoir by movement of the film from a first position to a second position, the film including first and second layers, each of first and second layers comprising a blend of a polypropylene and a styrene ethylene butadiene block copolymer. Peritoneal dialysis systems are also provided and may include a peritoneal dialysis machine and a disposable cassette defining at least one pump chamber and having a multiple layer film extending over a portion of the at least one pump chamber, the film including first and second layers, each of the first and second layers comprising a blend of a polypropylene and a styrene ethylene butadiene block copolymer.