Study on the Aging Rules of Rigid Polyurethane Foams at Indoor Storage and Different Hygrothermal Conditions

The aging rules of rigid polyurethane foam (PUR) at indoor storage and different hygrothermal conditions have been studied. Four parameters, which are mass, dimension, compressive strength and compressive modulus were tested. At indoor storage, mass, dimension and compressive strength vary slowly with an increase in aging time, while compressive modulus decreases quickly. PUR is sensitive to relative humidity (RH) verified by accelerated hygrothermal aging, and hydrolysis of ester group is the main reason resulting in the decrease of compressive properties. The filling with fire retardant and glass beads had some effect on hygrothermal aging properties of PUR. The addition of fire retardant increased compressive strength with aging time in the total trend, but it made dimension stability worse. The addition of glass beads slightly improved hygrothermal aging properties.