Fabrics composite thermal insulation

From the beginning of this century, the demand for asbestos fibers grew in a spectacular fashion for numerous applications, in particular for thermal insulation in steam engines and technologies (4). Moreover, the development of the Hatschek machine in 1900 for the continuous fabrication of sheets from an asbestos—cement composite opened an important field of industrial application for asbestos fibers. 

Their reviews suggest that standard bench-scale tests for separate determination of flame resistance, thermal insulation/protection, and heat resistance may be undertaken on a single fabric or a composite form in a manner that reflects a real application or product requirement. 

In Sections 24.3 and 24.5 the flammability and fire resistance of individual fiber/fabric type are discussed. However, as also discussed before, the fire resistance of a fabric not only depends upon the nature of components and the FR treatments applied, but also on fabric area density, construction, air permeability, and moisture content. Nonwovens, for example, will have superior properties to woven or knitted structure, even if all other variables are kept the same.93 The air entrapped within the interstices of any fabric structure and between layers of fabrics within a garment assembly provides the real thermal insulation. For effective thermal and fire resistance in a fabric structure, these insulating air domains need to be maintained.22 In general, for protective clothing and fire-block materials, for best performance multilayered fabric structures are employed. The assembly structures can be engineered to maximize their performance. It is beyond the scope of this chapter to go into details of these composite structures hence the reader is referred to the literature on specified applications and products available. 

It is noteworthy that each of these has an outer fabric containing meta- and para-aramid blends (see Chapter 8) for good fire protection and durability. However, a number of inner layers, whether joined to the outer or part of the Uner comprising breathable polyurethane or PTFE membranes, are also a common feature. Thirdly, the use of thermally insulative nonwoven interlayers and comfortable meta-aramid/FR viscose innermost linings are also present. It is the ordering and exact interlayer compositions that appear to be the major differences, while each design attempts to provide the common properties of fire resistance, thermal insulation, moisture transport, and comfort. 

In addition to providing for high heat absorption and heat dissipation per unit mass expended, ablative materials are used because they provide an automatic control of surface temperatures by self-regulating ablative degradation excellent thermal insulation tailored performance by varying the individual material components and composition of the ablative system design simplicity and ease of fabrication and lightweight and low-cost materials. 

The proposed monograph is about sihca aerogel composites. Silica aerogels are known for their excellent thermal insulation properties in many industrial applications. This monograph explores novel but practical approach to fabrication of silica aerogel composites so as to push their application boundaries beyond thermal insulation. 

Lightweight holiow fibre thermally insulating fabrics for winter clothing have been produced by Unitika. A composition containing 98 parts nylon 6 and two parts sodium stearate treated-a-AljOj particles (AKP-30) was melt-spun to form fibres with degree of hollowness 30%, drawn and made into woven fabric exhibiting heat transmission 1.6 x 10 " W/cm°C. 

Electrically insulating and thermally conductive qualities are important in computer chips fabrication. One approach taken is based on boron nitride fillers which offers these two properties. There is also a need to develop materials which are thermally conductive but electrically insulating in high humidity conditions. Polyurethane composites filled with aluminum oxide or carbon fiber can be used for this application. Figure 19.15 shows the effect of the amount of filler on thermal... 

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