Membranes of polyurethane based materials including polyester polyols

The present invention relates to a membrane comprising: polyurethane polyester containing membrane having a gas permeation rate of 1.5 · 10-5 m3 / m2 of nitrogen gas for 24 h or less if the average thickness of the membrane is about. 0.5 mm. The invention also relates to a container and cushioning device utilizing such membrane as well as a hydropneumatic battery. The invention further provides a method of making a diaphragm wherein a laminate membrane extrudes a layer of a first layer and a second layer of urethane having a polyester polyol having hydrogen bonding hydrogen containing functional groups which bind to the polyurethane of the first layer.