Polyurethanes Insulation

Cryogenic Polyurethane Insulative foam for cryogenic tankage... 

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. 

ASTM C 945-81 (1987) Standard Practice for Design Considerations and Spray Application of a Rigid Cellular Polyurethane Insulation System on Outdoor Service Vessels, 11 pp (Comm C-16)... 

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. 

Polyurethane Enamels. Small volumes of this enamel type are used in applications for which the temperature does not rise above approximately 105 C. These enamels are made from hydroxyl-bearing polyesters and blocked isocyanates. During the heating cycle in the enameling process the isocyanates become unblocked and react with hydroxyl groups of the polyesters to form a cross-linked polyurethane film. Wires so insulated can be directly soldered, without prior removal of the polyurethane insulation. 

Potential for metal ion oxidation (Fig. 1.16a), an oxidative degradation of polyurethane insulation, true for both kinds (80A and 55D)... 

Most synthetic polymers are made in chemical plants, with the completed products shipped to fabricators for final molding, spinning, blowing, etc. Polyurethanes are different in that the polymer itself is made on the spot in the facilities of appliance and furniture manufacturers, at automotive suppliers, and on construction sites. For example, polyurethane insulation is formed within the shell of a refrigerator during appliance assembly. Usually, there is no need to drive off reaction byproducts to force the reaction to completion and the polyurethane is formed without addition of heat. 

Material carbon steel lined with neoprene latex polyurethane insulation Surface area 875 m exposed to air (say 9(X)), 227 to ground (say 250). 

Fig. 1.24 Two designs of pacing leads using cabled conductors. Above A traditional multifilar coiled conductor for stylet delivery lies parallel to a cabled conductor. The lead is slightly oval (Medtronic 5044. Never marketed). Below. Coaxial design (Medtronic 3830 SelectSecure ). The cathode cable lies at the center of the lead and is then covered with a protective cover (ETFE) and over that a conventional silicone insulator. It is then surrounded with a polyurethane insulated multifilar coiled anode conductor. There is no lumen for a stylet. (Permission for use Medtronic.)...

A contemporary ventricular defibrillator lead consists of multiple internally separated metal wires that are externally encased in silicone rubber or polyurethane insulation. This allows the lead to function similarly to a standard pacemaker lead, i.e. transmission of electrical pacing/sensing signals between the heart and generator, but also structurally provides a separate pathway that participates in the delivery of shocks. This pathway includes what are commonly referred to as the lead "coil(s)." Shocks are delivered across the heart between the coil(s) and potentially the ICD can. Each element of the lead has its own pin that may connect to the ICD header. 

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 use of Pulverised Fuel Ash (PFA) as a filler for low density polyurethane insulation foams has been evaluated. The chemical and physical interaction of PFA and polyurethane were investigated. The mixing characteristics of PFA lyurethane was examined. PFA/polyurethane foams were tested to see if their properties were within the... 

Certain polyether polyurethanes possess ideal properties to make relatively small, maneuverable, and slippery (in blood) leads. Of those available at the time, only the Pellethane 2363 series met our needs. In 1975, the first polyurethane-insulated lead was implanted in a human as part of a spinal stimulator. The softer Shore 80A and stiffer Shore 55D polymers were tested extensively in vivo over the ensuing 5 years for cardiac use. This may leave the impression that we implanted neuro leads in humans first, then tested the material. In fact, the neuro implants were based on the... 

---