Properties Of Spacer Fabrics Research Articles

Development and Standardization of Testing Equipment and Methods for Spacer Fabrics

Spacer fabrics are three-dimensional textile structures consisting of two textile cover surfaces and a spacer thread. Up to now, spacer fabrics have been tested according to standards for flat textiles or other non-textile materials. However, these standards do not take into account the special requirements for testing spacer fabrics. Some sample holders of the testing devices are not designed for the thickness of the spacer fabrics, so that the tests cannot be carried out. In other tests, the samples can be mounted, but the test results are falsified by the methodology, e.g. strong compression of the sample before testing. Therefore, objective comparisons among spacer fabrics or between spacer fabrics and conventional flat textiles or non-textile materials cannot be made in all areas of application. The focus of this paper is in the developing of testing devices for seven test setups (1. sample preparation, 2. maximum force, 3. thickness, 4. compression, 5. mass per unit area, 6. permeability to air, 7. abrasion resistance). The new testing devices and methods were designed and manufactured using the method of an iterative development process. The following steps were carried out identically for all seven test setups: deficit analysis, development of concepts, construction of test benches, evaluation, transfer into standards. As part of this research work the developed devices where both tested and evaluated by industrial partners as well as later translated into a standard by the German Institute for Standardization (DIN e.V.). As a central result, a first standard for the testing of spacer fabrics was created and published: DIN 60022–1 “Spacer textiles – Terms and definitions, sample preparation” [4]. For testing textiles, it is important that geometrically identical and structurally intact samples are prepared. Therefore, this standard provides measurement tools and methods for the evaluation of sample quality (e.g. roundness of circular samples, maximum offset and shearing of the surfaces). Two further test methods (determination of thickness and air permeability) were developed and are now being transferred to standards. Within the new test standards, the special properties of spacer fabrics are given special consideration. In addition to the test methods developed within this work, further research is necessary. In particular, the tilting stability (linked to the in-plane and out-of-plane shear measurement) as well as the compression behaviour of spacer fabrics are important tests that need to be analysed and further developed. Therefore, further research is planned for six test methods (1. compression hardness, 2. compression set, 3. tilting stability, 4. pressure point distribution, 5. abrasion resistance, 6. maximum force). This work enables standardized testing of spacer fabrics and thus objective comparisons not only between various spacer fabric constructions but also with conventional flat textiles and with non-textile materials.

Prototyping and analyzing physical properties of Weft knitted spacer fabrics as a substitute for wound dressings

In this research, the required physical properties of weft knitted spacer fabrics, as an alternative for wound dressings have been investigated. For this purpose, weft knitted spacer fabrics with five different fabric structures have been produced on the electronic flat knitting machine. Moreover, in order to compare the properties of the produced fabrics with available wound dressings in the market, two kinds of wound dressing have been prepared from the market. Then, the physical properties of the spacer fabrics and the wound dressings such as air permeability, water vapor permeability, thermal conductivity, compressibility and absorbency have been measured and compared. The results show that in weft knitted spacer fabrics with the same fabric structure of the outer layer and different inclination angle (the angle formed between the outer layer and the spacer yarn), by decreasing the inclination angle, the fabric air permeability, water vapor permeability and absorbency decrease and the thermal conductivity and compressibility increase. Moreover, the use of tuck stitches in the outer layer of the spacer fabric leads to an increase of air permeability, water vapor permeability, absorbency and thermal conductivity and decrease of compressibility. The wound dressings also exhibit less air permeability and compressibility than weft knitted spacer fabrics. On the other hand, they possess higher water vapor permeability and absorbency. According to the results, among the examined weft knitted spacer fabrics in this research, the fabric with the tuck stitches in the outer layer is specified as the most appropriate alternative for wound dressing, in case of wounds with low exudates.

The influence of fabric parameter on low-stress mechanical properties of polyester warp-knitted spacer fabric

ABSTRACTLow-stress mechanical properties of spacer fabrics are investigated from the six polyester warp-knitted spacer fabrics and have been tested on Kawabata instrument. Three different types of spacer fabrics with a thickness of 2, 3.1 and 4 mm were prepared using three different face layer structures, namely locknit, rhombic mesh and hexagonal net and the influences on fabric properties were studied. The fabric with secured locknit structure and higher fabric thickness shows the high values in the compression, bending and shear properties. However, in case of tensile strength, the fabric of open mesh structure with higher fabric thickness decreases the tensile properties. The 3.1 mm fabric thickness along with hexagonal net structure shows the fine response on compression properties and reasonable effects on the other low-stress mechanical properties.

Investigation on the impact and compression-after-impact properties of warp-knitted spacer fabrics

The paper reports an experimental study on the influence of spacer fabrics' structures, that is, different surface stitches, fabric thicknesses, and diameters of spacer yarns, on the impact and compression-after-impact properties of warp-knitted spacer fabrics. Low-velocity impact tests, damage deformation characterizations, and compression tests after impacts were performed on six spacer-fabric specimens knitted on a double needle bar Raschel knitting machine. The impact method was flat-sphere (a flat striker contacted with a fabric wrapped on a hemispherical steel anvil). Deformation processes of typical spacer fabrics, force–displacement/time and energy–time curves, impact damage, and residual strength were analyzed and discussed; moreover, peak force, absorbed energy, damage depth, and the drop-off rate of residual strength were involved to estimate impact and compression-after-impact properties of the spacer fabrics with different structures. The results show that with the closed surface structure and coarser spacer yarns, the fabrics have the characteristics of lower peak forces, higher energy-absorption ability, lower damage depths, and higher drop-off rates of residual strength. Fabrics with higher thickness are of the features above but they do have lower drop-off rates