Spacer fabrics

The main purpose of middle layers is to provide additional (thermal) insulation. Nowadays, these layers are often made of fleece materials with good air entrapment properties. Their thermal conductivity (typically 0.03-0.04 W/mK) is near from air (0.026 W/mK). The thermal resistance of such layers is directly correlated with their thickness, provided that no air movement occurs within the fabric. Thermal conductivity and air permeability also are generally dependent on the fabric density (Yip and Ng, 2008). Conduction has been shown to be the main heat transfer mechanism through textile layers as long as the fibre volume fraction is higher than 9% (Woo et al., 1994). However, materials with very low density (like spacer materials) allow radiant and convective heat transfer. This was demonstrated by Das et al. (2012) who compared a spacer fabric middle layer with two non-woven middle layers and showed that the contribution of this spacer fabric to the overall insulation was higher than the two other samples in a non-convective mode, while it was the lowest in a forced convective mode. The positive effect of metallised interlayers with low emissivity on the reduction of... 

Yip, J., Ng, S.P., 2008. Study of three-dimensional spacer fabrics physical and mechanical properties. J. Mater. Process. Technol. 206, 359-364. 

In 2009, Rawlings, Inc. introduced a football helmet with a TPU cushioning system that comprised pressured gas chambers (Rawlings, 2014a). The pneumatic liner system included a network of interconnected chambers containing a spacer fabric composed of poly(hexamethylene adipamide), commonly known as nylon, to maintain the pad design. The comfort liner included a new urethane foam material that is engineered to respond with dilatant characteristics upon impact. The newly available Tachyon helmet contains individual gas chambers placed within multiimpact foam. 

During recent years, there have been new developments in the area of spacer textiles ITV Denkendorf has developed a process in which two separated textile fabric layers, covered by transparent foils, are connected by a spacer fabric. Due to this specific construction, an air space is created which provides a high degree of heat and acoustic insulation. Spacer fabrics, laminated or coated with transparent foil on both sides, are increasingly used for transparent thermal insulation. Woven spacer fabrics can be produced up to 600 mm in width and are used, sometimes with filUng, for sound damping (Fig. 2.8). 

Hon X, Hu H, Silberschmidt W. A study of computational mechanics of 3D spacer fabric factors affecting its compression deformation. J Mater Sci 2012 47(9) 3989. 

Thermo-physiological and climate-controlling properties of the spacer-fabrics will also be discussed in this paper. These tests directly relate to the functional comfort characteristics of the spacer-fabric structures which include thermal resistance, thermal absorpitivity, water vapour permeability, and evaporative heat loss. In all of the tests undertaken, comparisons are made to results obtained for traditional compression bandages and padding bandage materials. 

Four spacer fabrics identified as Black (1), White (2), White (3) and Blue (4) were used to study the pressure transference at various pressure raises. Four padding bandages (PBla to PB4a) recently available at Drug Tariff were also used for comparison. It should be mentioned that the pressure distribution of 10 commercial padding bandages were earlier studied and reported elsewhere . ... 

A fkbric extension device (Figure 2) has also been developed at the University of Bolton which cilitates the extension of spacer fabrics at the required length. The pressure transference of spacer fabrics at various extensions was measured utilising this device. 

The basic properties of padding bandages and spacer fabrics used in this study are given in Table 1. 

Table 1. Basic Properties of Padding Bandages (PB) and Spacer Fabrics...

Fig 4. Illustration of a 3D Spacer Fabric Structure Effect of pressure transference of commercial bandages... 

Spacer brics are three-dimensional structures that can be engineered to incorporate a wide range of attributes and hence fulfil specific pre-determined requirements. Knitted spacra fabrics can be produced on both weft and warp kiutting machines. Each of the fabric faces can be designed independently, as well as the middle layer (spacer layer), in terms of yams and structures and this will determine the unique individud properties of each fabric [1,2]. Spacer fabrics have been studied and developed for a few years now but the number of variables that can possibly be input in their constmetion gives such a wide range of possibilities that many are still to be developed and exploited commercially. 

This research focuses mainly on one of the least exploited properties of spacer fabrics the elastic properties. Considering that the best attribute of spacer fabrics is their thermophysiological properties, a combination of these with the elastic properties gave birth to a very important medical application compression ther y. This research has focused on pressure garments, namely knee braces and pressure garments for third degree bums. 

Two pq)ers have been previously published which discussed the development of novel three-dimoisional spacer fabrics for knee braces. In these publicadons a thorough analysis of the tensile and thermophysiological properties of each of the structures developed was also presented and critically compared with commercially available fabrics for the same end-use [3,4]. 

A niunber of knitted spacer fabrics have been developed, tested and analysed during this research with view to study their suitability for using as a knee brace material. Of these, two spacers have been identified as having the desirable properties sought after for such supports. These two novel fabrics have been produced by two different methods, weft knitting and warp knitting. 

Ehie to the shortage of matmal of the commercial products the specimen dimensions used were reduced to 15cmx2.San. The test specimens for the spacer fabrics were cut to the same dimensions as for fire commercial products in order to make a direct comparison of the mechanical properties. 

Table 2 shows the results of the elastic properties of the novel knitted spacer fabrics developed for knee braces according to the British test method BS7505. 

Anon., Karl Mayer, Spacer Fabrics - An Alternative to Laminated Foam Fabrics (April 1992). Verkauf Information Service, N. 656, Karl Mayer Textilmaschinenftibric GmbH,Obertshausen, Germany. 

In most load-bearing medical applications, however, warp-knitted structures, which include both weaving and knitting features, will generally be preferred. Specially constructed Raschel machines that have two needle bars and several guide bars are commonly used. The two needle bars, working alternately, contribute to the versatility of the products. The basic principle is that each needle bar produces a flat fabric the two fabrics are simultaneously connected to each other to form a three-dimensional structure. Examples of structures that can be produced are a double-sided, double thickness structure two separate fabrics with different structures and yarns, joined as needed tubular structure, straight or tapered, and with branches and a sandwich or a spacer fabric with filler yarns. 

Barauskas R and Abraitiene A (2011), A model for numerical simulation of heat and water vapor exchange in multilayer textile packages with three-dimensional spacer fabric ventilation layer . Text Res J, 81(12), 1195-1215. 

Key words wound, debridement, dressing, antibacterial, antiodour, venous leg ulcer, padding bandage, compression bandage, spacer fabric bandage. 

Anon (2002) Spacer fabric focus. Knit International, 109,20-22. 

In spacer fabrics, two knit layers are linked by threads that cross between them. 

Figure 1.9 High-bulk 3D fabrics, (a) Cross-laying, (b) Vertical lapping, (c) Needled spacer fabric.

As described in Chapter 11, 3D spacer fabrics have many applications in sport and leisure clothing. Sports shoes are a major market, but 3D fabrics are also used in underwear and outerwear. Two groups of features are important. The open structure provides good heat and moisture transfer, thus providing thermophysiological comfort in leisure activities, enhancing performance in athletic competition and providing... 

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