Insulation foams

Heat losses in residential buildings occur primarily via convection from the roof ( 25-35%) followed by air leakage and walls ( 15-25% each). Adequate insulation in roof and exterior walls is therefore a significant energy-saving investment. Table 5.7 compares thermal conductivity and environmental merits of different insulation materials (Dewick and Miozzo, 2002). The insulation efficiency is typically 

TABLE 5.7 The Thermal Conductivity and Environmental Performance Rating of Common Building insulation Materials 

Insulating material Density (kg/m ) Conductivity at 10°C (W/m-K) Environmental impact rating 

The various applications of plastic materials in building constmction are summarized in Table 5.8, which include both thermoplastics and thermoset materials. The number of + symbols quahtatively indicates the volume use of the particular plastic material in the specific product category. In addition to the main product categories discussed already, the table includes low-volume products such as plastics used in roofing or as moisture control films. 

TABLE 5.8 Main Types of thermoplastics Used in Building Construction 

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Phosphorus-Containing Diols and Polyols. The commercial development of several phosphoms-contaiuing diols occurred in response to the need to flame retard rigid urethane foam insulation used in transportation and constmction. There are a large number of references to phosphoms polyols (111) but only a few of these have been used commercially. 

Sources of human exposure to formaldehyde are engine exhaust, tobacco smoke, natural gas, fossil fuels, waste incineration, and oil refineries (129). It is found as a natural component in fmits, vegetables, meats, and fish and is a normal body metaboHte (130,131). FaciUties that manufacture or consume formaldehyde must control workers exposure in accordance with the following workplace exposure limits in ppm action level, 0.5 TWA, 0.75 STEL, 2 (132). In other environments such as residences, offices, and schools, levels may reach 0.1 ppm HCHO due to use of particle board and urea—formaldehyde foam insulation in constmction. 

Phenol—formaldehyde resins are used as mol ding compounds (see Phenolic resins). Their thermal and electrical properties allow use in electrical, automotive, and kitchen parts. Other uses for phenol—formaldehyde resins include phenoHc foam insulation, foundry mold binders, decorative and industrial laminates, and binders for insulating materials. 

In Europe total consumption of plastic foam insulation for 1992 was 29 x 10 m (>12 billion board ft) withHttle or no growth seen from 1991. AU products were expected to grow by an average of 1% due primarily to the continued effects of the economic recession. 

Foam Insulation Since foams are not homogeneous materials, their apparent thermal conductivity is dependent upon the bulk density of tne insulation, the gas used to foam the insulation, and the mean temperature of the insulation. Heat conduction through a foam is determined by convection and radiation within the cells and by conduction in the solid structure. Evacuation of a foam is effective in reducing its thermal conductivity, indicating a partially open cellular structure, but the resulting values are stiU considerably higher than either multilayer or evacuated powder insulations. 

The tank is typically about sixteen inches in diameter and about four to five feet tall. The top of the tank is domed upward and the bottom of the tank is also domed upward in a concave manner. The outside of the tank is insulated with a polyurethane foam insulation that is squirted into the gap between the tank and a thinner sheet metal jacket. The polyurethane is made of two different components that react and harden when mixed. Included in the mixture is a blowing agent that causes the polyurethane to expand in a foam-like manner. Prior to about 1980, water heaters were insulated with fiberglass insulation. The foam insulation process was developed to allow automation and increased manufacturing speed and reduced costs. A side benefit was improved insulating ability leading to a slight increase in efficiency. 

Dichlorofluoro-ethane (CCI2FCH5) The leading substitute blowing agent for CFC-11 in rigid foam insulation applications such as construction (commercial, residential, and public), appliances, and transport vehicles. 

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. 

Chlorotetrafluoro-ethane (CHCIFCF5) A potential medium pressure refrigerant for chiller applications. It is designed to replace CFC-12 as a diluent in sterilizing gas. A potential replacement for CFC-11 and-12 in rigid foam insulation applications. 

It should be noted that prior to 1987, total CFC emissions were made up from aerosol sprays, solvents and foam insulation, and that refrigerant emissions were about 10% of the total. However, all the different users have replaced CFCs with alternatives. 

Polyurethane foams Insulating systems for high-temperature marine pipelines [1389]... 

Figure 1 indicates a typical nitroglycerin facility "inside out" wood frame construction at a concrete floor slab. Note that the exterior cant strip, the lead conductive floor cant and the wood cap are all sloped to discourage product build-up and facilitate cleaning. This assembly also indicates spray-on foam insulation as an optional construction item. At Radford AAP this is a safety approved insulation system. The insulation at Radford AAP received a chlorinated rubber paint coating for weathering. 

Formaldehyde Germicide, pressed-wood products, urea-foimaldehyde foam insulation (UFFI), adhesives, paints, plastics, carpeting, gypsum board, ceiling tiles and panels, wood paneling. 083 2A... 

Formaldehyde from particle board, pressed wood, urea-formaldehyde foam insulation, plywood resins, hardwood paneling, carpeting, upholstery ... 

A few special considerations must be dealt with when reusing PET from consumer sources in chemical recycling. For example, the PET must be clean and free of contaminating materials. Using plant scrap assures the manufacturers of both the identity of the resin and its purity. Using mixed colored resins may pose a problem, although when they are used in products that are not visible to the consumer, such as foam insulation, color is not a factor. 

Freeman Chemical uses about 25 million lb of postconsumer PET bottles and film scrap to make polyols for the production of rigid foams. The company estimates that more than 50% of the laminate foam insulation used for construction is made from recycled material. 

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