An Investigation on the Formation Mechanism of the Porous Structure of the PU Films

Abstract

Application of polyurethanes (PU) is extending into various fields, such as artificial leather, microfiltration, moisture-permeable water-proof material, and osmosis membranes. The polyurethane coated films are a porous material with dense surface backed by a porous substructure; they possess an excellent adsorption and permeability, a useful strength and toughness. These properties are closely related with their microstructure. The microstructure of PU film may be altered dur ing its formation. The investigation of the formation mechanism of microstructure of leather type PU films made from different PU/DMF/additive systems is reported in this paper. The microstructure of the different PU films is also elucidated and ana lysed on the triangular phase diagram consisting of PU/DMF/H2O additive system and precipitation values.