Mechanical properties and dimensional stability of water-blown PU foams with various water levels.rtf

Polyurethane foam (PUF) is an outstanding material for various applications, which is manufactured by propelling liquid isocyanate-polyol mixture to form foams in the presence of blowing agent. In order to reduce the ozone depletion and environmental pollution from organic blowing agents, waterblown PU foams were prepared with various water levels (311phr), and the effects of water level on mechanical properties and dimensional stability of the foams were investigated in this study. The results indicated that water level had important effects on microstructures of water-blown PU foams and therefore affected the physi-mechanical properties because water not only formed the gas for foaming but also involved with the chain-extension of PU matrix. The volumetric changes of PU foams with various water levels were below 0.5% after kept at either -25C or 85C for 30 days, indicating the excellent dimensional stabilities of resultant PU foams. Keywordspolyurethane foam; water blowing; mechanical properties; dimensional stability; foam morphology;