The hottest multiple deformation mechanism and yar

2022-07-31
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Multiple deformation mechanism and yarn forming performance

multiple deformation can change the geometric properties of synthetic filament, and then give the fabric fullness, bulkiness, warmth and better hand feeling. The successful development of its mechanism provides a favorable experimental basis for the industrialization of deformation theory

traditionally, most textile fibers, especially the yarns and fabrics made of natural fibers, have good hand feel and warmth retention. This is because the geometric properties of these fibers can make textiles, but their industrialization is only inferior to that of linmen. They are plump, bulky, warm and give good hand feel. However, the textiles made of synthetic filament do not have the above good wearability, and can only change the geometric properties through deformation processing to meet the application needs. At present, the main deformation processing methods include false twist deformation, air deformation, stuffing box deformation, winding processing, two-component deformation and different shrinkage deformation

the false twist deformed monofilament is of regular spiral shape. The fabric has high elasticity, fluffy, coverage and warmth retention, but it has poor hand feel and aurora. The surface layer of air textured yarn forms many silk circles and arcs along the yarn axis. The yarn core is in the shape of "braid" or "parallel" tow, and the size is randomly distributed. Its fabric has high fluffy, coverage, warmth retention and soft luster. However, due to the high bending stiffness of the yarn, the formed fabric has rough hand feel and high stiffness. In order to further improve the structural properties of textured yarn and the hand feel of fabric, multiple texturing is being studied and developed

ideal model of textured yarn formation

multiple deformation refers to two or more consecutive deformations; Compound deformation refers to the combination of mechanical deformation (including thermomechanical deformation and fluid deformation) and physical deformation (differential shrinkage deformation); Meso deformation is between macro deformation and micro deformation, or different deformation and crimp shapes are applied to each filament

multiple deformation

mainly includes: false twist deformation (hot air flow deformation) and winding processing combination; Combination of false twist deformation and air deformation; Combination of double twist and false twist deformation

winding processing and yarn forming morphology

winding processing is carried out for false twist deformed yarn, that is, compressed air is used to form winding nodes through the winding nozzle, which changes the morphological structure of false twist deformed yarn and significantly enhances the binding force between monofilaments. After improvement, it can be used for knitting or shuttle weaving processing, without changing other properties of the fabric and increasing the complexity of post-processing, and the processing cost is low

air textured yarn, false twist textured yarn, combination of false twist textured yarn and air textured yarn and wool yarn were spun with the same raw materials and the same linear density. The experimental results show that the yarn morphology is more fluffy and the curl morphology is more irregular after the combination of false twist textured yarn and air textured yarn; Air textured yarn has higher bending stiffness and bending hysteresis, while wool yarn has lower bending stiffness; The bulkiness of the four kinds of yarns is almost the same; The air textured yarn has low compression recovery after being rubbed clean

In order to compare the fabrics made of various kinds of deformed yarns, four kinds of yarns, air deformed yarn, air deformed and false twisted yarn, false twisted and air deformed yarn, and wool yarn, were selected as raw materials. The experimental analysis of the products was carried out on the basis of the same linear density, the same fabric structure and weaving process, The fabric properties of the two combined textured yarns are close to those of wool fabrics, indicating that the multi textured yarn significantly improves the yarn morphology and structure, and is similar to wool yarn. However, due to the need for two deformation processing, the processing cost is high, so it is of little significance to promote the application

comparison of stiffness of various deformed yarns

comparison of compressibility and bulkiness of various deformed yarns

the combination of double twist and false twist deformation can spin crepe effect deformed yarn, which is characterized by strong twist, high residual torque and bulkiness

pet multifilament yarn is first twisted T1 by double twisting spindle, and then heat set, and then twisted T2 by false twister. T1 and T2 are generally in the same direction, and t = T1 + T2 is heat set. After passing through the false twister, T2 is untwisted. Therefore, processing crepe effect textured yarn is similar to superimposing twist on textured yarn and heat setting. The residual torque of crepe effect textured yarn consists of two parts. One part of the residual torque is caused by false twist deformation, and the other part is formed by double twist, which is the superposition of the above two parts. However, the thermal setting effect of these two parts is different

SEM photos of various threads

schematic diagram of crepe effect textured yarn processing

1, double twist spindle 2, multifilament 3, feeding roller 4, heating box 5, false twister 6, output roller 7, winding

strong twist textured yarn is both dense and linear, and crepe effect textured yarn is both bulky and three-dimensional crimp, which is an ideal morphological structure of crepe

the residual torque of crepe effect textured yarn is higher than that of general strong twist yarn, and the residual torque of crepe effect textured yarn with 600 twist/m is higher than that of crepe effect textured yarn with 1200 twist/m. Therefore, crepe effect textured yarn has high potential energy, producing strong crepe effect and high bulkiness

handle evaluation of various textured yarn fabrics

shape diagram of crepe effect yarn

relationship between residual torque of twisted yarn and added twist

relationship between residual torque of crepe effect yarn and added twist

composite yarn

composite yarn is generally made by false twist deformation or air deformation of different shrinkage multifilaments. First, two groups of high shrinkage yarn and low shrinkage yarn are selected for deformation processing, and then heat-treated in the relaxed state. The yarn with higher shrinkage will produce shrinkage force, while the yarn with lower shrinkage will be bent into curls or loops. The experimental parameters and test reports will be automatically calculated and printed. These deformations are superimposed on the original deformed yarn, making the deformation more random and irregular. Now, many groups (more than two groups) of filaments with different shrinkage rates are developed, and the curl deformation is more complex and random in both shape and size

morphological structure model diagram of several groups of different shrinkage filament after shrinkage

the structure of composite yarn after heat treatment is more bulky and disordered

the yarn with lower linear density has thinner and denser curl in the outer layer of the yarn; The filaments with higher linear density are distributed in the inner layer of the yarn, with thinner and thicker curls, resulting in changes in the radial direction. According to the properties of each monofilament, special spinnerets shall be designed, i.e. different pore diameters, different pore numbers and relevant distributions. Different shrinkage and different linear density filaments shall be obtained through special spinning and drawing processes

POY monofilament with different linear density and birefringence were spun with different spinneret holes, and the monofilament with low linear density had higher birefringence; On the contrary, it has low birefringence; FDY monofilament with different linear density has different boiling water shrinkage, lower linear density has lower boiling water shrinkage, on the contrary, it has higher boiling water shrinkage

strength and elongation curve of each monofilament

strength and elongation performance of each monofilament of FDY (average value of 10 tests)

micro deformation yarn

micro deformation makes the deformation probability and crimp shape of each monofilament different. The purpose is to simulate the performance of natural fibers, such as knot and cotton twist. At the same time, the overall length of the yarn is uniform, and the partial length is uneven. 4. Experimental conditions, experimental results, calculation parameters, gauge position automatic storage forms, such as coarse details, twists, knots, etc. According to different "sections", it can be divided into rough detail processing and twist section processing

in terms of thick and thin section processing, PET fiber is uneven in length during conventional stretching, which is called "thin neck effect", but it is not easy to control. The coarse and fine processing technology is designed according to the product requirements and is controlled by PLC

schematic diagram of producing "thin neck"

schematic diagram of producing "knuckle"

in knuckle processing, the process parameters controlled in the process of false twist deformation are stretching, twisting, heating, cooling and untwisting. Under normal conditions, PET fiber will not be melted. If the above parameters are properly adjusted, and part of the "fiber melting" or part of the "fiber not untwisted" can be realized according to the requirements of the product, part of the twist knot will be formed on the false twist deformed yarn

professor wangshanyuan is the director of the textile materials research and development center of Donghua University, the convener of the light textile review group of the Academic Degrees Committee of the State Council, and a member of the expert group of the National Postdoctoral Management Committee. (end)

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