Chapter VI Performance Understanding and Testing
This chapter concentrates on the various properties of clothing materials (extracted from the various chapters of the syllabus), aiming to unify the factors affecting material properties (including fiber, yarn, structure, post-treatment, etc.) Performance.
1. Basic requirements: Understand the various performances of clothing materials: physical and mechanical properties, chemical properties, appearance properties, health care performance, and sewing processing properties.
2. Key points: examine the definition, influencing factors, testing methods and indicators of various taking properties of clothing materials.
3. Difficulties: Master how the changes in taking performance change with factors.
4, teaching methods: classroom teaching and experimentation.
introduction
Different clothing materials have different performances, and the range of clothing applications and end uses will be very different. Therefore, knowing and mastering the various properties of clothing materials, it is helpful to properly select materials, reasonably design garments, and wear clothing satisfactorily, with a multiplier effect. The properties of the garment materials include physical and mechanical properties, chemical properties, appearance properties, and performances such as health care performance and sewing processing properties.
Section 1 Physical and mechanical properties of clothing materials
First, the definition
The property reflected by the relationship between stress and deformation caused by the external force of the fabric is called the physical and mechanical properties of the fabric. It contains properties in terms of strength, elongation, elasticity and wear resistance.
Second, the strength performance
1. Tensile strength and elongation at break of fabrics
When the fabric is subjected to a large tensile force during the administration, tensile fracture occurs. The tensile force when the fabric is subjected to the force fracture is called the breaking strength; the percentage of the deformation and the original length generated during the tensile fracture is called the elongation at break. The tensile fracture properties of the fabric are determined by factors such as the properties of the fiber, the structure of the yarn, the texture of the fabric, and the post-dyeing process.
(1) Properties of the fiber: The properties of the fiber are the determining factors of the tensile fracture properties of the fabric. The breaking strength of a fiber refers to the maximum tensile force that a fiber of unit fineness can withstand, in units of CN/dtex. Among natural fibers, hemp fibers have the highest breaking strength, followed by silk and cotton, and wool is the worst. Among chemical fibers, nylon has the highest strength and ranks first among all fibers, followed by polyester, polypropylene, vinylon, acrylic, chlorin, rich and viscose. Among them, viscose fiber strength is low, but slightly higher than wool, in the wet state, its strength drops a lot, almost wet strength is only 40~50% of dry strength. In addition to viscose fiber, the wet strength of wool, silk, vinylon and rich fiber also decreased, but cotton and hemp fiber, except for its wet strength, did not decrease but increased. Polyester, polypropylene, chlorin, nylon, acrylic, etc., due to low moisture absorption, make their dry and wet strength almost the same. As for the elongation at break, the hemp fiber is the smallest, only about 2%, followed by cotton, only 3 to 7%, silk 15 to 25%, and wool is the first of natural fiber, up to 25 to 35%. In chemical fiber, the elongation at break of vinylon and viscose fiber is the lowest, about 25%, and other synthetic fibers are above 40%.
Therefore, the tensile properties of various types of textile fibers are different: cotton and linen are high-strength and low-stretch, wool is low-strength and high-stretch, while nylon, polyester, acrylic, etc. are high-strength and high-stretch, in addition to vinylon and Silk is a medium-strong stretch. Generally, fine and long woven fabrics have better tensile properties than coarse and short woven fabrics.
(2) Yarn structure: In general, the thicker the yarn, the better the tensile properties; the increase of the twist is beneficial to the improvement of the tensile properties; when the configuration of the twist is the same, the strength of the fabric is increased; the strength of the strand fabric is high. For single yarn fabrics.
(3) The structure of the fabric: under the same conditions, the more the number of interlacing of the yarn within a certain length, the shorter the float length, and the greater the strength and elongation at break of the fabric. Therefore, the tensile properties of the plain weave are the best in the three original tissues, followed by the twill weave, and the satin weave fabric is the worst.
(4) Post-dyeing and finishing: The effect of finishing of the fabric on the tensile properties should be determined according to the circumstances, which has advantages and disadvantages.
The tensile properties of the fabric can be expressed by the indexes of breaking strength, elongation at break, length of fracture, elongation at break, work of fracture and the like. The sum of the general latitude and longitude latitudinal work in the world is used as an indicator of the toughness of the fabric.
2. Tear strength of fabric
During the wearing of the garment, the yarn on the fabric is caught by the foreign matter and is broken, or the fabric is partially pulled and pulled and torn in half. This damage of the fabric is called tearing or tearing. At present, China has a project to evaluate the tear strength of fabrics in the testing of cotton-woven fabrics and other chemical fiber fabrics. The influencing factors of the tear strength of the fabric are the same as the tensile properties. The tear property is also related to the interlacing resistance of the yarn in the fabric. Therefore, the tear strength of the plain weave fabric is the smallest, and the fabric of the square weave is the largest. The grain and twill weave are in between. The tear properties of the fabric can reflect the style characteristics of the fabric, such as the active and the knot.
There are three methods for testing the tear strength of fabrics: single slit method, trapezoidal method, and drop weight method. These three methods are suitable for testing dyed and finished fabrics, various woven fabrics, and lightweight nonwoven fabrics, respectively. Knitted fabrics are generally not tested for tearing.
3. Burst strength of fabric
The fabric is partially damaged by the load perpendicular to the plane of the fabric, which is referred to as a top crack or a top break. The rupture is related to the arching and arching of the fabric for clothing, and is similar to the force of gloves and socks. The burst test provides information on the multi-directional stretch characteristics of fabrics, especially for knitted fabrics, three-way fabrics, and non-woven fabrics.
Fabric Craft,Fabric Weaving,Craft Fabric,Fabric Painting Patterns
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