Study on Preparation and Properties of High Permeability Polyurethane Composites with Low Swelling

The water vapor permeability and water-swelling property of Polyurethane (PU) membranes with hydrophilic group and the PU composites were investigated. The water vapor permeability of the PU membranes increases with increasing polyethylene glycol (PEG) content. The highest water vapor permeability of PU membrane reaches 5,500 g/m 2 ×24h, whose expansion ratio reaches fifty-eight percent. The PU composites have three PU layers. The best surface layer of the composite is PU with fifteen percent PEG content, and the best base layer is PU with one hundred percent PEG content. The middle layer uses PU with PEG content from fifty to one hundred percent. The water vapor permeability of the PU composites can reach 4,000 g/m 2 ×24h, and the water-expansion ratio of the composites is below four percent when the surface layer of the composites contacts with water.