Insulating capacity

Poly(organosiloxane)s have a number of outstanding properties such as thermal and oxidative stability, water and chemical resistance, electric insulating capacity, selective permeability to gases, and biocompatibility. 

By heat stability is exclusively understood the stability (or retention) of properties (weight, strength, insulating capacity, etc.) under the influence of heat. The melting point or the decomposition temperature invariably forms the upper limit the "use temperature" may be appreciably lower. 

Fiberboards are manufactured primarily for panels, insulation, and cover materials in buildings and other structures where flat sheets of moderate strength and/or insulating capacity are required. They also are used as components in doors, cupboards, cabinets, furniture, and millwork. 

Vacuum circuit breakers show a very small stroke due to the high insulating capacity of vacuum. In a gas, the mean free path length ZF of molecules, atoms or ions is reciprocal to the gas pressure p /p 1 Ip. 

Another factor augmectting the heat conductivuty of plastic foams under conditions is the absorbed moisture. For example, for CCljF-foamed polyurethane at 25 °C and a relative humidity of 65%, the ambient moisture diffusion rate is 10-20 g/m for 24 h. Especially strong is the effect of moisture on heat conductivity if the temperature differential across the sample is considerable. For example, in plastic foams used in cryogenic technology, the inner layers are exposed to low temperatures the water vapor first condenses and is then convected into ice. Since the thermoconductivity of water and ice are 0.5 and 1.5 kcal/m x h °C, respectively, even minor tunounts have a considerable detrimental effect of the heat insulating capacity of a foam material... 

Foamed carbon has 600 times the thermal insulation capacity of the same weight of firebrick and is therefore used as a self-supporting thermal insulation material in furnaces or in fire-retarding sandwich-constructions. Foamed carbon cores are used in foundry technology, because they are easily produced and can be easily removed by combustion from inaccessible cavities. Furthermore foamed carbon is utilized as a filter material for the filtration of corrosive materials, as sintered plugs in gas inlets, as an electrode material and as a catalyst support. 

Thermal conduction occurs primarily through the solid polymer it is the gas that provides thermal insulation. In closed-cell foams, restriction of convection Insulates further and choice of the gas, particularly fluorocarbons, produces the maximum insulating capacity. On the other hand, the gas in a closed-cell foam aggravates the coefficient of thermal expansion and contraction most seriously when it is used in refrigeration and condenses to a low-volume liquid. If the gas in a closed cell is a flame-retardant fluorocarbon rather than air, it may contribute to overall flame retardance of the polymeric material. 

Optical gas sensors generally have some characteristics such as a high insulating capacity, independence of electrical noises and operation in safety. Moreover it is possible for them to detect a variety of gases by choosing a gas sensing material. For environmental use of optical sensors, applications for NO , SOj, CO2 and CO are expected. 

PCBs were first manufactured commercially in 1929. Because of the insulating capacity and flame retardant nature of PCBs, they were widely used as coolants and lubricants in transformers and electrical equipment. PCBs were also commonly used in the formulation of a great variety of common products such as plastics, paints and varnishes, pesticides, carbonless copy paper, adhesives, sealants, newsprint, fluorescent light ballasts, and... 

The insulating capacity achieved by the IGU is described by a physical parameter called thermal transmittance, respectively U-value. As illustrated in Figure 41.3, it can be defined by the amount of heat Q, which is transmitted through an area A within the time period t along a temperature gradient AT (11.1). 

The insulating capacity is influenced by the internal heat transfer hi, the heat transfer in the cavity l, which can be divided into 17% heat conduction, 17% convection and 66% radiation and the external heat transfer h. so that the U-value can be calculated according to the standard DIN EN 673 [1] (11.2). 

Good electrical properties glass has a low dielectric constant and good insulation capacity. 

The primary energy consumption amounts to about 300 kWh for each cubic meter of AAC produced, which is much more economical than for similar materials. Owing to the high thermal insulation capacity of AACs, the ratio of primary energy consumption and heating energy consumption is particularly attractive. 

Tiles and slabs incorporating ceramic fibres offer the advantage of reduced thickness in conjunction with equally good heat-insulating capacity, but they suffer from the drawback of limited strength, so that they can suitably be installed only in relatively small kilns (up to about 3.6 m diameter) and in the static parts of... 

Cavities in parts introduce discontinuities in the flow path of heat through the wall thus increasing the insulating capacity. Anyway, the heat-sink effect caused reduced... 

There are many thermal benefits of treating textile structures with PCM microcapsules such as cooling, insulation and thermo regulating effect. Without phase change materials the thermal insulation capacity of clothing depends on the thickness and the density of the fabric (passive insulation). The application of PCM to a garment provides an active thermal... 

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