Elasticity of a cryo-insulation polymer foam coating in the temperature range 8-293 K

An apparatus is developed for investigating the dynamic deformation propert ies of cryo-insulation coatings in the temperature range 8- 293 K. One type of cryo- insulation material polyurethane foam - is chosen as the object o f investigation. Test measurements on a polyurethane foam "pack'' (metal su bstrate with a polyurethane foam coating) are performed at 0.01 Hz in the t emperature range 8- 293 K. A jump in the temperature dependence of the dyna mic shear modulus (by two orders of magnitude) is observed in the temperatu re range 54- 63 K. This feature is attributed to the solidification of the air present in the pores of the polyurethane foam. Such a transition result s in cementation of the polyurethane skeleton of the coating by the nitroge n and oxygen "ice'' that is formed. (C) 1999 American Institute of Physics.