Closed Cell Rigid Polyurethane Foams Based on Low Functionality Polyols: Research of Dimensional Stability and Standardised Performance Properties.

Currently, polyurethane foam producers come across the several problems when petroleum-based polyols are replaced with low functionality biomass, or waste-based, polyols. In addition, the dilemma is intensified with regulations that require full or partial replacement of blowing agents that can cause high ozone depletion with alternatives like water, which causes the formation of CO2.

Therefore, these gases diffuse out of the foam so quickly that the polymeric cell walls cannot withstand the pressure, consequently causing huge dimensional changes at ambient temperature and humidity. Even though the theoretical stoichiometric balance is correct, the reality shows that it is not enough.

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Therefore, polyethylene terephthalate waste-based polyol was chosen as a low functionality polyol which was modified with high functionality sucrose-based polyol in order to obtain dimensionally stable polyurethane foams in the density range of 30-40 kg/m3. These more stable foams are characterized by linear changes no higher than 0.5%, short-term water absorption by partial immersion no higher than 0.35 kg/m2, and water vapor resistance factors up to 50.