Thermal and Mechanical Properties of Polyurethane Foams and a Survey of Insulating Concretes at Cryogenic Temperatures

摘要

Thermal and mechanical properties of expanded plastics, foams, are reported. The system studied was rigid, closed cell, CCl3F blown, polyether based polyurethane. The primary temperature range of study was 100 to 300 K; however, several properties were determined to 4 K. The nominal densities of the foams tested were 32, 64, and 96 kg/cu m. Properties reported are thermal conductivity, thermal expansion, strength and moduli in tension and in compression, proportional limit, yield strength, ultimate strength, and shear strength. Physical properties were determined both parallel and perpendicular to the orthogonal axes of the bulk supplies. The gas content of the specimens was determined using a gas chromatograph-mass spectrometer and with a gas displacement pycnometer. Empirical procedures for estimating the temperature dependent thermophysical properties were developed. These procedures are based on the experimental data and utilize the characterization parameters for molar gas concentration, gas pressure, and cell morphology. Regulations affecting vapor dispersion in the area around liquefied natural gas facilities make it attractive to construct dikes and impounding areas out of materials having low thermal conductivities. Several insulating concretes have the general properties required for such applications. Screening tests were done to determine the thermal conductivity, modulus of rupture, and the compressive strength of several polyester based materials with glass bead or perlite aggregate and of portland cement based materials with vermiculite or polystyrene aggregate. A bibliography resulting from an extensive literature survey of lightweight concretes is presented. Seven of the references which were particularly applicable are presented in annotated form.