A permeability model of packed particles material based on 2-dimensional fractal gradation spectrum

The permeability property of a packed particles material has been caught much attention, it depends upon its pore characteristics caused by the particle accumulation, but the current empirical formulas and the permeable theory could not reveal the effect of the particle accumulation thoroughly. In this paper, a theoretical formula is derived, and the fractal gradation spectrum is adopted to confirm the particle size distribution (PSD), furthermore the pore feature is determined by the particle size and accumulation features, finally a permeability model of the packed particles material is established. In this model, the effect of PSD on pore features is estimated more thoroughly than those in conventional models, and the calculated results are more accurate and verified experimentally.

Evaluation on the Air Permeability Properties of the Mainstream Sportswear Brands

The present study investigated the air permeability of three representative sportswear brands products (OUDIKE, NIKE and an unknown brand bought from the boutique) in Hong Kong marketplace. It was found that NIKE sportswear had the highest air permeability (0.23kPa*s/m) among the samples, which indicates that it allows more air flow passing through the textile and provides good comfort property to wearer, while OUDIKE samples showed the lowest air permeability in capacity (0.08kPa*s/m). The fiber content and fabric structure may be the reason that affects the air permeability. This study would provide a comparative information about air permeability property of the mainstream sportswear brands product in Hong Kong market.

Evaluation of the air permeability of elastic knitted fabrics and their assemblies

Purpose The purpose of this paper is to evaluate the air permeability of knitted fabrics containing elastane fibre and their seams applying both the new approach based on fabric thickness measurement at different pressures and standard method. Design/methodology/approach Investigations were performed with commercially available eight polyester knitted fabrics containing different elastane yarn proportion. Bonded seams were laminated applying the urethane thermoplastic adhesive film of 0.175 mm thickness. Bonds were laminated by heat at 5.6 kPa pressure applying pressing device GTK DEA 25 R at 140°C temperature for 40 s duration. Sewn seams were assembled with 607 covering chain stitch applying 5.0 stitches per cm density and 512 overedge chain stitch applying 5.0 stitches per cm density. Specimens without and with the seams were conditioned in standard atmosphere conditions according to the standard LST EN ISO 139 before air permeability testing according to the standard LST EN ISO 9237. Standard thickness of the investigated knitted fabric was determined according to the standard EN ISO 5084. It is known from literature that the porosity is dominant factor influencing the air permeability of knitted fabrics. Therefore, the assumption was made that due to fabric porosity knitted fabric thickness being measured at different pressures also may differ. Thus, the permeability property may also be related to the difference between fabric’s thicknesses being measured under different pressures which may be applied with different material thickness gauges. Findings There was shown that fabric assemblies make the significant influence on the textile permeability to air. The results obtained indicate that the air permeability of the investigated knitted fabrics depends not only on their structure parameters but also on the fabric seam type. Air permeability of the specimens with the seams was lower than one of specimens without the seams. The highest decrease in permeability which ranged from 19.9 per cent up to 60.0 per cent was determined for the bonds. Fabric specimens with 607 covering chain stitch seam were in the second place with regard to the previously considered parameter. And, their permeability was decreased from 0.6 per cent up to 52.6 per cent. Changes in the air permeability of the specimens with 512 overedge chain stitch seam were lowest in the range of investigated assemblies. Based on the determined results, it was concluded that the thickness difference of the specimens with and without seams measured at different pressures is related to fabric porosity which makes the significant influence on the air permeability. Practical implications The samples of investigated fabrics were taken from the two companies which manufactures leisure clothing and sportswear such as skiing or swimming costumes, etc. Thus, the obtained investigation results are significant not only for clothing science but also leads the improvement of clothing quality in fashion industry. Originality/value Assuring the comfort of the human body is one of the most important functions of clothing, especially of sportswear and leisure wear. Knitted fabrics should not only be elastic, but also have high air permeability for easily transmit of the perspiration from the skin to the atmosphere, thus making the wearer to feel comfortable. In this research, the air permeability of commercially available polyester knitted fabrics containing different amount of elastane was investigated and the influence of fabric assemblies on the air permeability property was evaluated. A new approach based on the fabric thickness measurement at different pressures and the standard methods for the evaluation of air permeability were used.

Air permability of worsted fabrics

Comfort is one of the most important aspects of clothing. Air permeability, one of the comfort charectaristics of fabrics, depends mainly on the fabric structure, which can be described by weave and yarn density. In this study, 16 worsted woven fabric samples were produced for winter clothing using eight frequently implemented weave types together with one warp density (28 ends/cm) and two weft densities (25 and 28 picks/cm). Additonally, semi-dull finish was applied on raw fabrics. Results revealed the effect of weave, weft yarn density and finishing process on air permeability of woven fabrics. 2/2 twill woven fabric, whose porosity is the lowest, have the lowest air permeability properties, therefore it is more convenient for winter clothing. It is observed that in all weave types, an increase at weft setting caused to decrease in air permeability and porosity values. Finishing process also leads to decreasesin porosity thereby to decrease air permeability property

Permeability Customisation through Preform Manipulation Utilising 3D-Printing Technology

The importance of preforming techniques is constantly increasing due to the fast development of liquid composite moulding processes. Besides traditional preforming methods such as tufting and stitching, tackifier based methods have developed rapidly. This paper presents a new methodology utilising 3D-printer technology for fabrics, through preform manipulation and thus enabling in-plane permeability property customisation. Two patterns of 45° and 90° with respect to the predominant permeability direction were printed onto the fabric consisting of parallel thermoplastic polymer melt strands. After a hot pressing stage the resulting preforms were characterised in terms of their in-plane permeabilities with an optical permeameter and compared to the original material's permeabilities. Furthermore a parameterised model is proposed describing the phenomena causing the manipulation by introducing a scale matrix for translating the original material's permeabilities into the permeabilities of the manipulated preforms.