A multilayer fabric with woven layers consists of a number of woven layers stacked on top of each other and held together with connection yarns in the third dimension (Z-direction). This article Knitting fair introduces to you.
Technical textiles are the fastest growing sector in the textile industry. Therefore, it is highly essential to develop all techniques and types of equipment in order to decrease the production time especially with the use of electronically equipped modern looms and communicated with computers.
The automatization of woven design is one of the ways to facilitate the work and to increase the production, especially in the conventional weaving of complex structure, due to the time consuming and difficulties involved in the manual design (e.g., the combination of weaves, seeking of stitches and introducing it, generating of lifting plan, doing cross-sections, etc. However, a number of CAD/CAM fabric woven structures with complicated weaves have been developed and represented in the form of 2D and 3D matrices.
Some of these researches depended on mathematical functions to describe and generate automatically the 2D and 3D weaves. In other words, the algorithm of the Kronecker Product was applied to describe weaves. In addition, other CAD/CAM software’s that deal with geometric modeling of woven structures have been developed to visualize the fabric appearance before weaving (Liao & Adanur, 1998; Lomov, Perie, Ivanov, Verpoest, & Marsal, 2011; Smith & Chen, 2009). However, they do not discuss all the problems due to the wide variety of weaves and stitching ways.
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Definition Multilayer fabrics
A multilayer fabric consists of several layers woven above each other with a maximum of 12 woven layers or 22 warp yarn layers and 23 weft yarn layers (unidirectional layers). The connection can be realized by connection yarns in the third dimension or by interlocking. As a result, the delamination resistance of the fabric increases and the manual labor of stacking different layers on top of each other could be decreased. All types of yarns can be used and combined. This combination could be different layers with different types of yarns but also in one-layer different types of yarns can be used.
A multilayer fabric with woven layers consists of a number of woven layers stacked on top of each other and held together with connection yarns in the third dimension (Z-direction). The geometry of the woven layers can be customized.
3D Weaving
The term 3D weaving is commonly used in reference to the weaving of cloths that have pre-designed three-dimensional shapes (multilayer fabrics) or can be directly manipulated by interlocking and non-interlocking methods into a 3D shape immediately after being woven. It is also used to describe the weaving of fabrics with substantial thicknesses, many times greater than the diameters of the yarns used to produce the fabrics.
3D Shape Weaving
Conventional projectile/rapier-dobby/ Jacquard looms can be used to produce certain three-dimensional shapes by weaving multiple layers of fabric interlinked to each other, similar to a ‘double cloth, treble cloth ‘formation, so that after being woven the layers of 2D fabric can be manipulated into the required 3D shape; for example, a dobby/jacquard loom can be used to produce the cellular structures. For obvious reasons, this method is also termed multilayer weaving.
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It is highly essential to have knowledge and understanding of double/treble cloths which are basic for the formation of multilayer fabric
Double cloths structures—The simplest structure of double cloth is composed of two series of warp threads and two series of weft threads. One series of each kind forming an upper or face fabric, and the other, an under or back fabric. It is necessary for the face picks, to be arranged in definite order with the backing picks, and the face ends with the back ends
Treble cloths structure—In treble cloths there are three series of warp and weft threads which form three distinct fabrics one above the other. Except for the forties, when a face pick is inserted all the center and back ends are left down; when a center pick is inserted all the face ends are raised, and all the backing ends are left down, while a backing pick is inserted all the face and central ends are raised.
For more knitwear knowledge, please pay attention to the knitting fair.
Source: textiles school
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Cleaning ensures sanitization and thus the safety of the artefact itself and others stored/displayed in its vicinity. At the same time, the process invariably alters the character of textile to a certain extent. Cleaning ensures removal/deactivation of soil and harmful organic matter from the artefact. However, a small number of surface molecules from the textile might be eroded in the process as well. This leads to weakening of the textile and might cause alteration in colour spectrum/ depth etc. Controlled cleaning techniques in conservation laboratories focus on minimizing this damage. However, not much scientific data is available on the efficacy of present cleaning techniques employed in conservation laboratories. Presently aqueous cleaning and solvent cleaning are primary modes utilised as next step to dry tools. Additionally, novel cleaning technologies like enzyme wash and ultrasonic wash provide soil specific methodology that would reduce the threat to the base fabric. This article Knitting fair introduces to you.
The present paper is a systematic analysis of these cleaning techniques and their impact on aged museum fabrics, i.e., cotton, wool and silk. Change in tensile strength parameters, whiteness index and yellowness index have been used as indicators to test the efficacy of different cleaning techniques on aged museum textiles. Numerical data generated by laboratory experiments clearly indicate that there is no standard cleaning treatment available for the three natural fibres. Each fibre has exhibited suitability to different cleaning treatment while balancing between restored whiteness and minimizing strength loss.
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METHODOLOGY
Cotton, wool and silk samples were selected for research. The samples were tested for determination of tensile strength and Whiteness Index and yellowness index. Samples were subjected to accelerated ageing as per the method suggested in the AATCC Test Method 26-1994. This ascertained that samples were brought to a condition of approximately 20years of ageing. Aged Cotton, Wool and Silk samples were taken for Tensile Strength testing and Spectroscopy. Standard testing procedures were followed to measure the indicators. Thereafter, the aforesaid samples were divided into 4 groups for wet cleaning i.e., home laundry, enzymatic cleaning, dry cleaning and ultrasonic cleaning. The samples were subjected to treatments as appropriate for their fibre content. For example in the home laundry group cotton was exposed to the detergent, temperature and conditions prescribed for selected fabrics. After wet treatment, the samples were again tested for loss in tensile strength and removal of yellowness. Recorded values for whiteness Index and tensile strength were then compared to determine the best possible method.
A Home Laundry
Home laundry techniques are probably the oldest and simplest means of sanitizing fabrics. The primary merit of this method is that the worker gets to closely interact with fabric at every stage of treatment. This ensures the possibility of simultaneous improvisation, while the fabric is still under treatment. A crucial advantage of this technique stands that professionals can modify the procedure as per suitability to the textile while retaining absolute control over the artefact at the same time. For the purpose of this study AATCC test method 61-2007 was followed. Test no 1A- was used as specimens subjected to this test should show colour change similar to that produced by five typical careful hand launderings at a temperature of 40+/-30C. Laundering machine was adjusted to maintain the designated bath temperature of 40+/-20C. The wash liquor was prepared with total liquor volume of 200ml and detergent concentration at 0.37%. The test was run in lever lock stainless steel canisters of size 75X125 mm with 10 steel balls in each canister. The laundering machine was run for 45mins after which each test specimen was rinsed in a separate beaker. Each specimen was rinsed three times in distilled water at 40+/-20C with occasional stirring and hand squeezing. To remove excess water, flat specimens were pressed between folds of blotting paper. Thereafter, specimens were air-dried, placed flat on a blotting paper. A commercial detergent was used for cotton fabrics whereas a neutral soap was used as ‘non-ionic’ detergent for wool and silk.
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Dry Cleaning/ Solvent Cleaning
A synonym of solvent cleaning, this technique has been widely used for cleaning of sensitive textiles like wool, silk, chiffons. Most sensitive fabrics that behave adversely to aqueous medium stand comfortable to dry cleaning. For the purpose of this research AATCC test method, 158-1995 was used where samples were dry-cleaned at a commercial workshop with perchloroethylene. Drycleaning machine with a commercial rotating cage was used. The sample fabric was placed in the machine and perchloroethylene was introduced. The machine was run for the specified period of time. The solvent was thereafter drained and centrifuged. The load was dried in a drying tumbler by circulating in warm air for an appropriate time. The specimens were removed from machine immediately and placed on a flat surface for drying.
Enzymatic Cleaning
Literature about the use of enzymes is available from the late ’60s. In 1988, Segal published a paper reporting important factors affecting enzyme activity and various immersion and non-immersion techniques of application. Contemporary studies have repeatedly noted the efficiency of Cellulase enzyme as an effective bio-polishing agent for cotton fabric which considerably preserves the strength and weight parameters of the fabric in contrast to other chemical techniques (Bhat, 2000). The primary advantage of using enzymes is that enzymes are substrate-specific. Thus if proven useful, they stand superior to all parallel techniques of achieving a desirable result. The concept utilized in this section of the study is that of bio-polishing. The phenomenon talks about removing the damaged superficial layer of the fabric and restoring the fresher subsequent layers (Doshi et. al, 2001). Since the fabrics used in this section of the research were both cellulosic and protein in nature Cellulases and Proteases were the enzymes used for the purpose.
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Ultrasonic Cleaning
The potential of ultrasonic cleaning in conservation has been recognized for some time. Barton et. al. (1986), reported that archaeological conservation in Europe has resorted to this type of cleaning in dealing with waterlogged wood, textiles and leather artefacts. The principle of ultrasonic cleaning is the generation of mechanical impulses through a liquid at high frequencies. These impulses create minute bubbles of vacuum which implode against the immersed object, creating shocks which clean its surface (Dallas, 1976). Thus ultrasonic cleaning technique is effective while remaining gentle in terms of time and handle. Therefore the possibility of using ultrasonic cleaning technique for removal of a superficial damaged layer of aged fabrics was explored to restore whiteness without considerable strength loss. For the purpose of the present study, samples were cleaned in ultrasonic cleaning machine at North India Textile Research Association, Ghaziabad (Figure 1). Three cotton samples were washed at a temperature of 50oC with a commercial detergent at a concentration of 5gpl (IS: 5785: 2005). The first sample was taken out of the machine after 5mins, second after 8mins and third after 11mins (Sethi, 2012). The samples were then dried on a flat surface. Whiteness Index and tensile strength of these samples were recorded thereafter. Similarly, silk and wool samples were treated at a temperature of 40oC with a non-ionic washing detergent at 5gpl. Again the samples were dried flat and values for Whiteness Index and Tensile Strength noted thereafter. Thus the samples in all three fibres were subjected to the above-mentioned cleaning treatments. Whiteness Index and tensile properties for these samples were noted before and after the cleaning treatments. Comparison of these values provided insight into the utility of these treatments for each fibre.
For more knitwear knowledge, please pay attention to the knitting fair.
Source: textiles school
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