William R. Proops

Thermal Conductivity of Rigid Urethane Foam Insulation in Low Temperature Service

. tion of moisture accumulation. Under the influence of the water vapor pressure gradient between the surroundings and the structure to be insulated, water vapor moves through the insulation toward the cold surface, to eventually condense as liquid water and freeze as solid ice, both of which have relatively high thermal conductivities and thus increase the effective thermal conductivity of the insulation. The rate at which this movement occurs

Boron and Antimony Compounds as Flame Retardants in Rigid Polyurethane Foam

ditives, and are not available in a sufficiently wide variety of liquid compounds. The reported work using boron compounds in polyurethane foams appears relatively limited (6). Dip-treating methods are ineffective because of the closed-cell structure of most rigid polyurethane foams, and compositions with built-in boron seem generally susceptible to hydrolysis under ambient conditions. Non-reactive boron-containing additives appear to be the most useful form at present. Antimony compounds have found some use in rigid polyurethane foams, primarily in conjunction with halogen compounds (7). However, the catalytic activity of some antimony compounds complicates their use as flame retardants.

Bromine, Chlorine, and Phosphorus Compounds as Flame Retardants in Rigid Urethane Foam

I n recent years, cellular plastics have received considerable attention and widespread acceptance in many market areas because of the advantages they offer in thermal insulation, cushioning, packaging, and flotation. Because many of these applications involve varying degrees of fire hazard, the performance of these cellular plastics when sub]ected to fire is often a major factor affecting the acceptance of foam for a particular application (1,2). Consequently, many studies of the flammability characteristics of plastics have evolved (3-21). A cellular plastic is an organic material and will burn when certain conditions exist. Many tests have been devised to describe the flammability characteristics of cellular plastics but no single test or perhaps no combination of a limited number

The Mold-Pressure Characteristics of Rigid Urethane Foams

cars and highway trialers. Indeed, numerous foam users have expressed high interest in obtaining a foam system which would enable them to singlepour a large panel or cavity without the use of expensive and cumbersome jigging. Such a system, of course, would also be required to have good properties such as low humid aging, a good flammability rating, little or no friability, good molding characteristics, and little or no shrinkage on cold aging. An extensive study was undertaken in an effort