Rigid polyurethane insulating

Not only are rigid polyurethane insulating foams energy efficient, they are durable as well. Du Pont recently completed an accelerated aging study to determine the length of time that the fluorocarbon remains in the insulation. The study found that one-half of the fluorocarbon remained in a one-inch thick piece of rigid polyurethane insulation after more than 80 years, and the half-life of fluorocarbon in a two-inch slab of polystyrene insulation is estimated at 75 years. 

As example, a rigid polyurethane insulation manufacturer may not make the statement that 5-1/2 inches of his product has an R-value of 34 unless he has tested samples 5-1/2 inches thick and the product, indeed, had an R-value of 34. That sounds fair enough. But, test instruments that will accomodate samples of this thickness are extremely scarce. Rigid polyurethane foams are quite efficient insulators, so great thickness is not required to achieve large R-values. In the case of the less efficient insulation materials, R-value of 34 can be achieved only with thicknesses far greater than can be accomodated by any test instrument. Therein lies the battle. 

The utilisation of P.F.A. (pulverised fuel ash) as a filler in rigid polyurethane insulation foams... 

THE UTILISATION OF P.F.A. rPULVERISED FUEL ASm AS A FILLER IN RIGID POLYURETHANE INSULATION FOAMS... 

The avadabihty of PMDI also led to the development of polyurethane-modified isocyanurate (PUIR) foams by 1967. The PUIR foams have superior thermal stabiUty and combustibiUty characteristics, which extend the use temperature of insulation foams well above 150°C. The PUIR foams are used in pipe, vessel, and solar panel insulation glass-fiber-reinforced PUIR roofing panels having superior dimensional stabiUty have also been developed. More recently, inexpensive polyester polyols based on residues obtained in the production of dimethyl terephthalate (DMT) have been used in the formulation of rigid polyurethane and PUIR foams. 

Difluorochloro-ethane (CH5CCIF2) An effective replacement for CFC-12 in rigid polyurethane, polystyrene, and polyethylene foam insulation applications. Uses include both residential and commercial construction and process piping. 

The largest use for rigid polyurethane is in construction and industrial insulation due to its high insulating property. Figure 12-7 compares the degree of insulation of some insulating materials. ... 

The plastic insulants are rigid, homogeneous materials, suitable as the core of sandwich panels. Such a method of fahrication is facilitated when using foamed rigid polyurethane, since the liquids can he made to foam between the inner and outer panel skins and have a good natural adhesion, so making a stiff structural component [40]. 

The glycolysis of rigid polyurethane foams produces polyol products which can be reintroduced into the production cycle of PUR insulation materials to form materials with properties practically equivalent to dtose of materials produced using virgin polyols. Aromatic amines produced as by-products in die glycolysis process are toxic and therefore undesired side products. The most frequently observed side product is diphenylmedianediamine (DMDA), which is formed... 

Rigid polyurethane foams can be made from either polyester or polyether prepolymers, which are crosslinked with polyfunctional isocyanates. The resulting foams are largely closed cell, with only about 5 to 10% of cells being open. Rigid polyurethane foams are widely used as insulation in commercial, residential, and industrial settings. 

Rigid polyurethane foams are mostly based on polyether alcohol and are highly cross-linked. Rigid foams are many times blown by halogenated alkanes like trichlorofluoromethane. These foams have closed cell structures and are used for thermal insulation. Semi-rigid foams are used in car crashpads and packaging. 

Rigid polyurethane foams account for 80% of MDI use, especially for construction (about half of this use), refrigeration, packaging, and tank and pipe insulation. Other uses are reaction-injection molding (RIM) applications (13%) and cast elastomers (2%). 

Rigid polyurethane foams are mainly used as insulating and damping materials (construction industry, cooling equipment, ship construction). 

Applications. The principal use for rigid polyurethane foams is lor insulation in various forms utilized by a variety of industries. Packaging constitutes another significant use and is often a foam-in-place opcralion lo protect industrial equipment such as pumps or motors. 

Thermal degradation of foams is not different from that of the solid polymer, except in that the foam structure imparts superior thermal insulation properties, so that the decomposition of the foam will be slower than that of the solid polymer. Almost every plastic can be produced with a foam structure, but only a few are commercially significant. Of these flexible and rigid polyurethane (PU) foams, those which have urethane links in the polymer chain are the most important. The thermal decomposition products of PU will depend on its composition that can be chemically complex due to the wide range of starting materials and combinations, which can be used to produce them and their required properties. Basically, these involve the reaction between isocyanates, such as toluene 2,4- and 2,6-diisocyanate (TDI) or diphenylmethane 4,3-diisocyanate (MDI), and polyols. If the requirement is for greater heat stability and reduced brittleness, then MDI is favored over TDI. 

More than 50% of the rigid polyurethane foams manufactured in the United States in 1994 are used in the construction industry (Table 10). About 60% of the total rigid foam is used in laminated boards and insulation panels about 30% is poured in place. Insulated appliances is another important use of rigid insulation foam. 

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