Foam polyurethane

Foams. Polyurethane foams are prepared by the polymerization of polyols with isocyanates. 

Data on the thermal conductivity for a variety of foams used at cryogenic temperatures have been presented by Kropschot Cryogenic Technology, R. W. Vance, ed., Wiloy, New York, 1963, p. 239). Of aJl the foams, polyurethane and polystiyene have received the widest use at low temperatures. The major disadvantage of foams is that they tend to crack upon repeated thermal cychng and lose their insulation value. 

Dry A filter manufactured from cotton wool, glass-fiber fabric, pleated paper, foamed polyurethane, cellular polythene, or other suitable materials. As the name suggests, the filter is dry in nature and has no oil coating. 

Foamed polyurethane. The basic chemicals are mixed in the liquid state with foaming agents, and swell into a low-density foam which sets by polymerization into a rigid mass. As the swelling material will expand into any shape required, it is ideal for the core of sandwich panels, and the sheet material skins may be flat or profiled. When the panels are manufactured the mixture is injected between the inner and outer skins and expands to the thickness required, adhering to the lining materials. 

Example 15.4 What is the heat conduction through a panel of foamed polyurethane 125 mm thick, 46.75 m long and 6 m high if the inside temperature is - 25°C and the ambient is 27°C ... 

Addnl Refs 1) W.G. Joseph, Use of Foamed Polyurethane in Decreasing Erosion in Guns , PATR 2520 (1958) 2) Anon, Polymer,... 

Unlike other polymers, we have no universally accepted chemical nomenclature for polyurethanes. Instead, we typically refer to polyurethanes in terms of their general characteristics. Thus we refer to flexible polyurethane foams , polyurethane elastomers , integral skin polyurethane foams , and others. 

Figure 25.8 Schematic diagram outlining the general process for making foamed polyurethane slabstock... 

How does the number of multifunctional isocyanate units in a foamed polyurethane influence the rigidity of a foam ... 

Why is it necessary to have a balance between the rates of crosslinking and expansion when manufacturing a foamed polyurethane What variables affect these rates ... 

Polytetrafluoro ethylene Polyurethane foam Polyurethane foam, fire retardant Polyvinylacetate... 

Certain incinerator chimneys are in hybrid stainless steel with an inner lining in sandwich resin/glass fibres with a core in foamed polyurethane. 

Foams are commercially produced several ways. Some polymerization processes produce their own foam. Polyurethanes, for example, are very exothermic. When they are formed, if a little water is present, CO2 will be a by-product. As the polymer forms, the CO2 will cause closed cell foam. As another example, a blowing agent can be injected into the molten polymer. The agent will later decompose, giving off a gas when the polymer is heated to melting. Epoxy resins are expanded into foams this way. 

Dike surface flow using soil, sand bags, foamed Polyurethane, or foamed concrete. ... 

Two other derivatives of toluene are the important explosive trinitrotoluene (TNT) and the polyurethane monomer toluene diisocyanate (TDI). TNT requires complete nitration of toluene. TDI is derived from a mixture of dinitrotoluenes (usually 80% o,p and 20% o,o) by reduction to the diamine and reaction with phosgene to the diisocyanate. TDI is made into flexible foam polyurethanes for cushioning in furniture (35%), transportation (25%), carpet underlay (20%), and bedding (10%). A small amount is used in polyurethane coatings, rigid foams, and elastomers. 

Lock Foam Polyurethane foam Nopco Chemical... 

Tenn Foam Polyurethane foam Morristown Foam Corp. 

Keywords Algae Castor ESO Foam Polyurethane Renewable Triglyceride... 

As described in Sect. 4.2.1 foamed polyurethanes can be obtained especially through the so-called water-crosslinking of suitable polyol/diisocyanate combinations. Carbon dioxide liberated during the reaction partially causes the expansion of the foam. For a number of reasons additional foaming agents (in the form of low-boiling liquids or CO2) are added in practice, i.e., in order to vary the foam density and the pore size. 

The toxicokinetics of 2,4- and 2,6-toluenediisocyanates in 11 chronically exposed workers at two flexible foam polyurethane production plants have been reported. The toluene diisocyanate concentrations in air varied between 0.4 and 4 pg/m in one plant and in the other between 10 and 120 p-g/m. In one of the plants, the plasma 2,4-toluene diamine levels were 0.4-1 ng/mL before a 4-5-week holiday and 0.2-0.5 ng/mL afterwards. The corresponding plasma levels of 2,6-toluene diamine were 2-6 and 0.5-2 ng/mL, respectively. In the other plant, the plasma 2,4-toluene diamine concentrations were 2-23 ng/mL before the holiday and 0.5-6 ng/mL afterwards and those of 2,6-toluene diamine were 7-24 ng/mL before and 3-6 ng/mL afterwards. The plasma concentrations of 2,4-toluene diamine were 2-24 ng/mL before a 12-day holiday, and 1-14 ng/mL afterwards. The corresponding values for plasma 2,6-toluene diamine were 12-29 and 8-17 ng/mL, respectively. The urinary elimination rates for 2,4-toluene diamine before the holiday were 0.04-0.54 and 0.02-0.18 pg/li afterwards. The corresponding values for 2,6-toluene diamine were 0.18-0.76 pg/li before and 0.09-0.27 pg/h after the holiday. The half-life in urine ranged from 5.8 to 11 days for 2,4- and... 

At one time or another practically every plastic and elastomer has been processed in a cellular form. Only two of the most commonly encountered foamed plastics will be considered here styrofoam and foamed polyurethane. Both of... 

---