Essay About Filament Types And Weave Structure Affect

School of Textiles and Design – Textiles 1
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[pic 1]SCHOOL OF TEXTILES AND DESIGN E17TXTextiles 1Semester 2 – 2015/16May 2016Duration: Two HoursExaminers: Dr Lisa Macintyre and Dr Danmei SunInstructions to candidates:All answers to all questions should be written in the answer booklet provided.Note you do not need to write the whole answer for the multiple choice questions but note the question number and the letter representing your chosen answer/s.Please mark the section and question number clearly for each answer you have provided.       Section 1.  Please attempt all questions.  Every question in this section is worth 4 marks.  Please note all answers to be written in your answer booklet (please write the question number and the letters of your selected answers).Select the ONE answer that has listed fibre/filament types in the correct order from biggest volume used to least volume usedPolyester > elastane/spandex > cotton > nylon/polyamide > woolPolyester > cotton > nylon/polyamide > wool > elastane/spandexElastane/spandex > cotton > polyester > nylon/polyamide > woolCotton > wool > nylon/polyamide > polyester > elastane/spandexCotton > polyester > elastane/spandex > wool > nylon/polyamideSelect ALL the true statements from the list below that correctly describe the relationship between ‘fibres’ and ‘filaments’.A fibre is short and needs to be spun to make a yarn, while a filament is long and can be used as yarn without further processing.The term fibre and filament can correctly be used interchangeably, they both describe the type of material, e.g. cotton or polyester, that a fabric is made from.Fabrics made from fibres are fuzzy/hairy while fabrics made from filaments are smooth.Filament yarns tend to be smoother, thinner and stronger than equivalent yarns spun from fibre, which leads to them having quite different end-uses.All fabrics made from natural materials are made from fibres and all fabrics made from man-made materials are made from filaments.Select the ONE incorrect statement from the 5 below.Tenacity is a measure of the relative strength of a fibre or filament in relation to its count and is measured in cN/tex.The resilience of a fibre or fabric is a measure of its ability to recover from compression.The stretch of a fibre, yarn or fabric tells us how well it will keep its shape in tight fitting garments.Fibre fineness refers to the cross-sectional diameter of the fibre and is normally measured in microns.  Fine fibres are considered better quality than coarse fibres.Dimensional stability is a measure of the ability of a fabric to maintain its shape and dimensions during use and laundry.  Select all of the definitions of non-woven fabrics that are correctly described.Felt is made by entangling animal fibres using heat, moisture and agitation.Mechanical entanglement uses inter-fibre friction to hold the fabric together.  Fibres are commonly entangled using barbed needles or water jets.  Any fibre can be mechanically entangled.Thermal bonding uses heat and pressure to melt fibres together.  All man-made fibres can be thermally bonded.Adhesive bonding uses adhesive/glue to bond the fibres in a fibre web.  Only thermoplastic fibres can be adhesive bonded.Stitch bonding is where webs of fibres and/or other materials are bonded together with multiple rows of warp knitted chain stitches.  Any fibre type can be stitch bonded and it is often used to combine other non-woven fabrics.Please select the one definition from the list below that is incorrect:‘Cellulosic fibres’ can be either man-made or natural but all are made of plant cellulose.‘Non-woven fabrics’ are fabrics made directly from fibre (not yarn).‘Warp knitted fabrics’ are knitted from at least 2 sets of yarns, with each needle being supplied with its own yarns (2 or more). ‘Weft knitted fabrics’ are knitted with yarns that run horizontally in the fabric and they can be knitted from a single yarn.‘Seamless bodywear’ (such as pants, bras, vests) can be knitted entirely without seams on small diameter circular knitting machines.Man-made fibre production involves various processes including filament extrusion, drawing of the extruded filament, texturising and cutting filaments into ‘staple’ fibres for different applications. Select from below the statements that are entirely true.Nylon is made through wet spinning process using solvents to get their polymer particles dissolved before extrusion. Lyocell is made through melt spinning process by setting a temperature higher than its melting temperature 200oC.The main purpose of drawing process is to increase strength of the filament by having the molecules in fibre more linearly orientated, in the meantime to produce thinner filament.Texturising is a process where a crimped shape is put into man-made filament in order to produce bulkier and more opaque yarns with desired degree of elasticity.Sometimes, man-made filaments are cut into “staple” fibres. The fibre lengths of the cut filaments will be approximately the same as the other fibres that the man-made filament is likely to be blended with. All the man-made filaments including polyester, viscose, lycra, and acrylic are regularly cut into staple fibres for the next stage of spun yarn production. Select from below all the untrue statements in relation to textile dyeing.Pigments are water soluble. They transfer from water, diffuse and attach to fibres through inter-molecule force. Dyes react to all fibres to form strongest bond. Disperse dye is the only dye class which can be used for any types of fibre materials such as cotton, wool and polyester. Furthermore it produces the best quality of dyeing.Dyeing at fabric form is always recommended because it has all the advantages such as:excellent evenness of dyeing; andgarments may be dyed to popular fashion colours as required quicklyDyes are fibre specific. For instance, acid dyes are made for dyeing protein and nylon fibres. If cotton is dyed by acid dyes, the dyes are not strongly attracted to the fibres as a result cannot get expected colour strength.Dyes are mainly used for natural fibre materials; pigments on the other hand are used for synthetic fibres.Select from below the one correct sequence for manufacture of woven fabrics.Warp preparation> weaving> sizing> finishingWarp preparation> sizing> weaving> finishingWinding> picking>shedding> finishing Sizing> cloth take-up> picking>finishingSizing>shedding>beat up>finishingSelect all the true statement in describing factors affecting woven fabric production speeds.Weft yarn insertion methods affect woven fabric production speed. eg. Air jet weaving looms have higher production speed than shuttle looms.Fabric construction parameters such as warp and weft yarn density, fineness of warp and weft yarns (or yarn count) as well as weave structure affect woven fabric production speed. The quality of yarn, especially warp yarn strength affects woven fabric production speed. One of the reasons behind sizing of warp yarns is to strengthen warp yarn.Generally speaking, the production speeds of synthetic fabrics are much faster compared to natural fabrics made of cotton and wool. This is mainly caused by the significant strength difference between the two types of fabrics.Generally speaking, the simpler the woven fabric structure and colour pattern effect, the higher the woven fabric production will be if other construction parameters are the same, such as the type of yarn and yarn sett of the fabric. Select ALL the untrue statements in describing printing and finishing of textiles.Screen printing is currently the most important industrial textile printing method; it has fast speed and is very economical for long runs in comparison to digital printing.Digital printing has all the advantages compared to screen printing such as: It is able to quickly respond to fashion changes and enables instant change of patterns;It is economical for both short and long runs; and The machinery and ink are relatively less expensive.Comparing to dyes, pigments have many advantages such as comprehensive range of colours,  environmental friendly due to the fact that no need for substantial wash off therefore less energy required and low cost.The ingredients contained in a printing paste include:water;thickener;dye or pigment;softener;chemicals required to aid fixation of dyes (eg., acids and alkalis);finishing agent for easy-care when printing cotton fabrics.Unlike easy care finishing which can be performed as part of printing process, anti-static finishing is a separate process used for fabrics made of natural fibres.       Section 2.  Please attempt all questions.  All questions in this section are worth 2 marks.  Please write your short answer in your answer booklet (2 or 3 sentences at most will be required)Name 2 cellulosic ‘bast’ fibres and 2 animal ‘hair’ fibres.Any 2 of bast: linen, hemp, jute, ramie and animal: mohair, angora, camel, cashmere, alpaca State 1 advantage and 1 limitation of wool for application in winter jumpers.Main advantage is warmth (or half mark for resilient, elastic, durable, absorbent without feeling wet) main limitation is felting in wash, or fine wools expensive and cheaper wools can be scratchyBriefly explain what is meant by the term ‘yarn slippage’ and give a specific example of circumstances under which a fabric would need to have low yarn slippage.This is where yarns slip at the edge of a fabric and so the seam can slip towards the edge opening up the fabric … low slippage is essential in products like parachutes and is important in any tight fitting garment,  1 mark for definition and 1 for example