User:Njbaugh/sandbox

Yarn Engineering
The purpose of yarn engineering is to optimize the performance and minimize the cost of textile products through the process of selecting the most effective raw materials, fiber type, manufacturing method, and yarn structure.

Yarns are used to make a wide variety of fabrics. Yarns are made up of either natural or synthetic polymer fibers. The properties of these fibers and how they’re put together dictate properties of the yarn as a whole. The different types of yarn used in the fabric result in completely different properties and therefore uses. The fibers are put together to make two main types of yarn: continuous filament and staple fiber. Continuous filament fibers are made up of long strands while staple fibers are composed of many shorter strands. The manufacturing process of yarn includes different step, each with their own purpose. These include carding, combing, drawing out, twisting, and spinning. The way the yarn is manufactured along with the properties of the fibers it was made from give the yarn important properties, such as thinness, flexibility, and porosity that determine the applications that the yarn can be used in. There are continual advancements in yarn engineering that result in novel and exciting applications in fields such as textiles and textile engineering. This article will explore the different parameters that go into engineering yarns and how they affect the properties of the resulting yarn product.

Raw Materials
Fibers are the foundational units for the structure of yarn and can be classified as either natural or man-made. Natural fibers are derived from plants, animal hair, saliva, and minerals. Man-made fibers are regenerated from natural resources or are synthesized. The fibers can either be used separately to make yarns or combined together.

Natural

 * 1) Cotton is the most utilized textile fiber in the world, consisting of over 90% cellulose. It is advantageous in that it is easily obtained in nature, absorbs moisture very well (holds up to 27 times its weight in water), has a low thermal conductivity, and it does not irritate sensitive skin. It provides better ventilation than artificial fibers due to its large amorphous portion. Also, cotton can blend easily with other fibers, making it versatile in acquiring properties, such as strength.
 * 2) Flax is produced naturally by wild-growing perennials and cultivated, annual flax plants. After flax is roasted and dried, the leaves and branches are removed and it is snapped to remove stem particles, producing broken flax and shives. It then goes through a swingline process which uncovers the fiber bundles and is taken to a spinning mill for further processing. Due to its properties, flax fibers are mostly used for apparel and house textiles.
 * 3) Wool is a primary textile fiber used for human apparel and is gathered from sheep and other animals. Wool is high in sulfur, distinguishing it from protein and silk fibers. It is scoured or cleaned to remove fat and sweat and then carbonized with sulfuric acid to remove plant-derived components. After it is dried and pressed, it can then be made into yarn at a spinning mill.
 * 4) Mainly produced in South Africa and the United States, mohair is a specialty animal fiber derived from the Angora goat. Mohair is a luxurious, lustrous fiber that is very durable, elastic, and resilient. (Franck)
 * 5) Silk is a protein fiber made up of carbon, hydrogen, oxygen, and nitrogen. It is the only natural filament fiber. Cultivated silk is derived from cocoons of domesticated worms which are fed mulberry leaves. Each cocoon will produce about 1,000 yards of continuous filament fiber. (Video) Silk fibers are fine and are often used to make comfortable, light fabrics.

Synthetic

 * 1) Acrylic fibers are based on polyacrylonitrile. Polyacrylonitrile is produced by addition polymerization of acrylonitrile, or vinyl cyanide. Commercial acrylic fibers are mostly copolymers of acrylonitrile and vinyl monomers.
 * 2) Nylon can be used in everything from textiles to cars. Nylon fibers are made by reacting amides and carboxylic groups to form polymers. It’s a synthetic polymer that can be modified to have different properties based on its synthesis.
 * 3) Polyesters are another synthetic material that is often used in clothing. Fibers made of polyester are very durable and resist stretching.
 * 4) Rayon is a synthetic fiber made from cellulose. Yarn made out of rayon is very fine and has a comfortable feeling. It was originally made to mimic the feel of silk and is a common materials used in clothing.

Types of Yarn
The type of material in the yarn distinguishes it from either a continuous filament yarn or a staple fiber yarn. Continuous filament yarns have long and thin cylinders of extruded material and are classified as either monofilament (single strands) or multifilament (multiple grouped strands). The cross section of filament is less than 1 mm. Staple fiber yarns are typically comprised of limited and much shorter length fibers, about 25-180 mm long. To be formed into yarn, the short fibers must be aligned in parallel and spun together to bond.

Manufacturing Methods
Manufacturing yarn takes place over several steps. Each step serves a specific purpose and contributes to the final structure and properties of the yarn. These steps are carding, combing, drawing out, twisting, and spinning. The manufacturing process is important to the overall performance of the yarn, because it affects the strength-twist relationship, in which the strength of a yarn is determined by finding an optimizing twist level. It also has a significant influence on the Yarn Comfort Index, which is rated on porosity, softness, and flexibility. (Elmogahzy)

A card is the first machine for spinning preparation. Carding is a process that cleans, disentangles, and blends slivers, which prepares the fibers to be spun into yarn. Carding causes parallelizing of the fibers, mixes, drafts, and forms slivers.(Gries) Combing occurs after the carding process. It is an extra processing stage that removes short fibers and contaminants and causes fiber parallelization. Combing cotton, for example, allows for yarns of finer titer to be spun, higher production speeds, and the reduction of yarn twist and breakage. (Gries) During the drawing process, the fibers are drafted which further reduce the weight per yard of the fiber. The fibers are further straightened by drawing, which causes the randomized directions of the macromolecules to be oriented in the fiber direction and a decrease in fiber diameter. (Gries, Richards). Twisting is the process which binds fibers or yarn together for added tenacity, especially in staple fiber yarn. More twist is added during each process to hold the fibers together to create yarn. The direction and the amount of twist will have an influence on the properties of the yarn.

Spinning has been a part of human development starting thousands of years before the Middle Ages. Back then it was very slow and required a lot of work. Then in 1828 Thorp created Ring Spinning. In 1967, Commercial rotor spinning was created. And then in the 1970”s Air-jet and Friction spinning was made popular. There are several different types of spinning:
 * 1) Ring-spun- Ring spinning is a process used in order to achieve a 'true twist' in yarn. This means that the yarn is twisted about its central axis in a helical pattern, which proves to be useful as a base in other methods.
 * 2) Rotor-spun- Rotor spinning is similar to ring spinning, but much more efficient. Also known as open-end spinning, it produces the same pattern as ring spinning by pulling one end of the yard from a rotating apparatus. This yields a three-layered structure, but with less strength due to the reduced tension during production.
 * 3) Air jet-spun- Air jet spinning is another method that has a high production rate. This process utilizes a machine equipped with high speed air, in order to create a bundle of parallel strands, reinforced with wrap fibers.
 * 4) Friction-spun- Friction Spinning produces bulky yarn by feeding yarn into a machine where twist is applied, producing a true twist with fiber loops. This method is similar to the apparatus of air jet-spinning, but with twisting incorporated.

Properties
There are several properties of the yarn that dictate its usefulness in different applications, these include thinness, flexibility, and porosity. The thinness of the yarn can determine how fine fabrics made from the yarn can be. The flexibility determines whether the yarn will be stretchable or stiff. For example, rope is typically made from stiff yarns as they are stronger, but clothing fabrics are made from slightly flexible yarn in order to increase comfort. The porosity of the yarn effects how long the yarn lasts, the absorbency, thermal comfort, and feel of the yarnPorosity/properties.

Smart Fibers
Smart fibers are fibers that can respond to an outside stimulus, whether it be electrical, chemical, or thermal, in a predetermined waysmart materials. These materials can be made to perform differently in different environments, allowing them to have a wide range of useful applications. An important part of yarn engineering is designing novel smart materials, as yarns made out of these materials can be useful in many applications.

Shape memory polymers (SMPs) are a specific subset of smart materials. SMPs are polymers that when heated above a transition temperature become elastic and can be reshapedsmart materials. When cooled back below the transition temperature, the SMPs take the form that they are in at that moment. This phenomena can be used to design specific shapes of fiber based upon the temperature of the environment.

Textile Engineering
Yarn Engineering is most important in the Textile industry, where yarn engineers work with textile engineers and machinery to create the most efficient mill as possible. With the advancement of technology, loom s, have become much faster. With this increase in speed engineers must consider the type of yarn they can use. It must be able to withhold higher velocity and acceleration, higher frequency of shed opening and more energetic weaving motions. Also looms are now automatic, so the yarn should minimize the potential machine stoppage that would stop the loom. One way to stop stoppages is weaving in a more ideal condition with low humidity and temperature.

References (unformatted, will be done for final draft):
Yarn Engineering: http://nopr.niscair.res.in/bitstream/123456789/24502/1/IJFTR%2031(1)%20150-159.pdf

Manufacturing: http://www.cottoninc.com/product/Tech-Assistance-Training/TextileBasicsEducationalCDs/Yarn-Manufacturing-Basics/

Continuous vs. Staple Yarn: https://www.textileschool.com/299/physical-classification-of-fibers/

How yarn is manufactured: http://www.madehow.com/Volume-3/Yarn.html

Yarn engineering: https://www.researchgate.net/publication/295803445_Yarn_engineering

Fundamentals of Yarn Technology: http://www.woolwise.com/wp-content/uploads/2017/07/Wool-482-582-08-T-13.pdf

Smart Fibers: http://iopscience.iop.org/article/10.1088/0964-1726/15/6/006/pdf

Porosity determination of jersey structure (Properites): file:///C:/Users/Neil%20%20Baugh/Downloads/Porosity_determination_of_jersey_structure.pdf

Alagirusamy, R. Das, A.. (2010). Technical Textile Yarns - Industrial and Medical Applications - 1.1 Introduction. Woodhead Publishing.

Franck, Robert R. Silk, Mohair, Cashmere and Other Luxury Fibres. CRC Press/Woodhead Pub., 2001.

Gries, Thomas, et al. Textile Technology : An Introduction. vol. 2nd edition, Carl Hanser Verlag GmbH & Co. KG, 2014

VIDEO- silk http://fod.infobase.com.proxy078.nclive.org/p_ViewVideo.aspx?xtid=44037#