Polyurethane insulation material

In the mid-to-late 1980s, growth estimates of the use of polystyrene and polyurethane ceUular plastic insulation materials and products were a healthy 10% per year and greater for phenoHc (40,41). The principal appHcation where strongest growth was forecast for these types was for roofing, especially single-membrane systems (42). 

Polyurethanes. This material is available in three forms - rigid foam, flexible foam and elastomer. They are characterised by high strength and good chemical and abrasion resistance. The rigid foam is widely used as an insulation material, the flexible foam is an excellent cushion material for furniture and the elastomeric material is used in solid tyres and shock absorbers. 

Some commonly used insulating materials are calcium silicate, mineral slagwool, glass fiber, cellular glass, and polyurethane. 

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 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 foams are excellent insulators, even better than polystyrene, and are used in refrigerators and refrigerated trucks and box cars. Polyurethane coating materials are popular additives to marine finishes and varnishes, particularly for gymnasium floors, bar tops, and other surfaces that take an abusive, abrasive beating. 

The thermal insulation materials used in the walls, ceilings, and floors of refrigerated storage are usually combustible, such as polyurethane and polystyrene foam, and could present an additional fire hazard. The insulation should be covered with a noncombustible barrier material a V2-in (1.3-cm) thickness of Type-X gypsum board or cement plaster is often used for this purpose. Where the floor is insulated, the floor insulation should be covered with a layer of concrete. 

Coagulation is not the only problem with materials intended for implantation, however. Cardiac pacemakers are intended to correct arrhythmias. Insulating materials for a pacemaker lead must be tough and long lasting. The first leads were insulated with polyethylene or silicone rubber. Neither material was considered ideal because of endocardial reactions (polyethylene) and limited durability (silicone rubber). The strength and flexibility of polyurethanes led to their introduction in 1978 as lead insulators. 

Foams have a large variety of applications. Solid foams are widely used as insulating materials. Due to the presence of air bubbles they have a low thermal conductivity. Polyurethane foams and Styrofoam are examples. Styrofoam is also used as a packing material. The light weight of polymer foams makes them attractive as filling materials to stabilize otherwise hollow structures. A natural solid foam is pumice stone. Metal foams are used in the automotive and aerospace industry as light and stable materials [567], Ceramic foams are developed for electronic applications as piezoelectric transducers and low dielectric constant substrates [568],... 

Polyurethanes are not suited as an insulation material in mains voltage situations due to the ability of the polyurethane to absorb moisture and lower its resistivity. Polyurethanes alone or in a combination with an epoxy can be used as a potting material. 

Overlays for plywood deserves mentioning. Overlays for plywood may be anything that conceivably can stick to the panel and have end use utility. Overlays include polyester or phenolic impregnated paper (either medium or high density types), fi berg I ass-re in forced plastic, fabric, high pressure laminates, aluminum, lead, polyurethane insulation and pebbles. The uses for plywood are extensive and marriage with other overlay materials expand these uses tremendously. 

The most suitable containers for cooling baths are plastic bowls (ice baths), Pyrex dishes (solid CO2 baths) and Dewar flasks (solid CO2 and liquid nitrogen baths). If Pyrex dishes are to be used below —20 °C, an insulated container can be prepared by placing a smaller Pyrex dish inside a larger one and filling the space between with an insulating material such as cotton wool, cork chips or polyurethane foam chips. Remember that foam chips will dissolve if they come into contact with many organic solvents. 

Polyurethane rigid foam is an excellent insulation material, particularly well suited for applications requiring high mechanical properties. In the form of laminated boards, they are applied on roofs, ventilated facades, ventilated double walls, masonry construction, single-wall masonry interior walls, floors and ceilings and for floor heating systems. 

The current polymer foam market is dominated by gas imbibed polystyrene, polyolefins and polyurethanes used in consumer products, packagings and construction markets. However, there is a growing market for high performance foam products. Insulation materials for aerospace, transportation and some construction industries are required to have higher temperature performance and non-flammability. In this respect polyimides are naturally the material of choice. 

The insulation material is polyurethane foam, MIL-P-76514, Type II, Class 1. 

Regulation, which my company has supported, would be a partial solution. While affecting only the residential market, it would set the precedent of establishing consistent testing and reporting methods for various insulation materials. The obvious superiority of polyurethanes and isocyanurates will thus be demonstrated. 

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. 

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