High thermal insulation materials

The applications for addition polyimides are for electronic/electrical materials such as printed circuit boards and insulators, as matrix resins for structural composites in aircraft and as thermal insulation materials. Recently the market for polyimide based structural composites has suffered from the termination and reduction of military aircraft programs. However, the possible emergence of the High Speed Civil Transport program (HSCT) may offer an opportunity for addition polyimides (2). 

Because the thermal diffusivity of SC water is comparable to that of many high quality insulation materials, gross radial temperature gradients can easily exist in a flow reactor. As shown in Figure 2, radial temperature gradients within the annular flow reactor are negligible. A computer program, which accurately accounts for the effects of the various fluid (solvent, solvent and solute, air) compressibilities on flow measurements, calculates mass and elemental balances for each experiment. A typical experiment evidences mass and elemental balances of 1.00+0.05. 

If a polymer is intended for use in applications requiring high thermal insulation, its thermal conductivity is very important. The low thermal conductivities of polymers, and of foams [12] made by expanding polymers and incorporating pockets of air or other gas molecules in the "cells" resulting from the expansion, when coupled with other desirable properties, have made polymers and polymeric foams the insulating materials of choice in many applications. 

Phenolic resin foam is an interesting material for the cellular insulation industry because of its high temperature resistance, fire resistance, and very low smoke generation [16]. The aqueous resole is crosslinked in the presence of a surfactant and a low boiling liquid, that volatizes during the increase ofviscosity or plasticity of the mixture. The surfectant is necessary to develop a uniform fine cellular foam stracture [1,6], Carbonization of phenolic foams yields carbon foams with an excellent thermal resistance, that are applied as high temperature insulation materials for the production of filters for corrosive agents and catalyst supports [1]. 

Epoxy or polyepoxide is a thermosetting polymer formed from reaction of an epoxide resin with polyamine hardener. Epoxy is used in coatings, adhesives and composite materials. They have excellent adhesion, chemical and heat resistance, good mechanical properties and electrical insulating properties. Epoxies with high thermal insulation, thermal conductivity combined with high electrical resistance are used for electronics applications. There are a few studies conducted on OPE-epoxy composites. 

Carbon fibers from isotropic pitch Isotropic pitch or a pitch-like material, such as molten polyvinyl chloride, is melt spun at high strain rates to align the molecules parallel to the fiber axis. The thermoplastic fiber is then rapidly cooled and carefully oxidized at a low temperature (<100 °C). The oxidation process is rather slow, so as to ensure stabilization of the fiber by cross-linking to make it infusible. However, upon carbonization, relaxation of the molecules takes place, producing fibers with no significant preferred orientation. This process is not industrially attractive due to the lengthy oxidation step, and because only low-quality carbon fibers with no graphitization are produced. These fibers are used as fillers in various plastics to form thermal insulation materials. 

Lee JK, Gould GL, Rhine W (2009) Polyurea based aerogel for a high performance thermal insulation material J Sol-Gel Sci Technol 49 209-220... 

This product has higher compressive strength, high utilization rate of space (1/3-1/5 of the thickness of traditional thermal insulation material), excellent sound insulation characteristics in addition to waterproof and fireproof, and can be widely used in machinery, sea vessels (ships), high-speed trains, refrigeration equipment, etc. (see Figures 40.5 and 40.6). 

In case of the thermal insulation, the technical limits are nearly reached today and a further improvement will affect aspects like the units transparency (yiP - Vacuum Insula-ti(Mi Panels) or their maximum size, not mentioning the costs. A functional transparent vacuum insulating unit with U-values of 0.1 W/(m K) is not available by now due to the technical problems of keeping the system permanently gas-tight. Therefore, the use of translucent Silica Aerogels, as a highly efficient insulating material inside the/Gf/ s cavity, represents the best possible thermal insulation at the moment. 

Within fire protection of building materials, intumescent coatings are among the most widely used products with some unique features. They require a much lower thickness and weight than the alternative thermal insulating materials, and they allow simple application in thin films with high performance. 

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