Study on the Relationship between Tensile Strength and Tensile Properties of Filament Yarn Composite Yarn Li Jun Wang Li (Yancheng Institute of Technology) (Donghua University) Differences in the properties of various components in composite yarns Performance of composite yarns and fabrics Will have a great impact. In the case of reverse twisting of the composite yarn, the relationship between the breaking strength of the composite yarn, the elongation at break, the twist of the single yarn and the twist of the composite yarn was analyzed through experiments. There is also a critical twist factor for the composite yarn. The elongation at break of the composite yarn is positively correlated with the twist coefficient of the composite yarn, and the composite yarn breaks strongly. The elongation at break is positively linear with the twist coefficient of the single yarn.
With the change of people's consumption concept and the improvement of the material living standards, the demand for clothing has also become increasingly gentrified and comfortable. Fine, light, and smooth fabrics have become more and more popular among consumers. The main trend of development. Filament staple fiber composite yarns are used for the development of such new structure products. There is a big difference in the structure between composite yarns and traditional staple yarns, which will inevitably affect the performance of yarns and fabrics. . Therefore, in order to make good use of composite yarns to produce high-quality fabrics, the structure and properties of the composite yarns of filaments and cotton staple fibers must be studied in depth, especially the relationship between the basic mechanical properties and the structure.
1 Test method The Plyfil composite yarns used in the tests were made of two different raw materials, namely polyester low-elasticity yarns and pure cotton combed yarns. The indexes of polyester low elasticity yarn and pure cotton combed yarn are shown in Table 1.
Table 1 Specifications of polyester low-elastic yarn and cotton combed yarn Item Fineness Breaking strength Mean value Breaking strength Mean value Variance/% Breaking elongation Mean/% Breaking elongation Mean Variance/% Polyester filament Cotton yarn Polyester/cotton composite The yarn processing is first performed through a yarn merging process and then through a twisting process in order to prevent the occurrence of cheek yarn defects during the process of barrel merging. The main purpose of the yarn is to ensure the number of composite yarns, balance the yarn tension, reduce the uneven twist of the composite yarn, increase the strength of the composite yarn, and improve the appearance. The main purpose of the twist line is to combine the two yarns of different properties, and also to improve the distribution of stress on the fibers in the yarn, thereby improving the quality of the composite yarn.
The strength of the composite yarn and the strength of the components in the composite yarn are related to the process of the twisting process. Therefore, in order to find the main factors affecting the strength and elongation properties of the composite yarn, the test parameters must be determined by the test method. Twisting degree is the most important factor influencing the strength and elongation performance of composite yarns. In the text, the tested composite yarns were untwisted and twisted on a Y331 twist testing machine, and then their strength and extensibility were measured. Due to the fact that the reverse twisting of the composite yarn is relatively stable, the composite yarn adopts reverse twisting, and the twisted length L is 2; the strength and elongation properties of the composite yarn 2.1 The main factors affecting the strength and elongation performance of the composite yarn For the sample variety, the determination of the factor level during the test should take into account the following two aspects: first, the requirement is the most commonly used; second, the requirement is more obvious. So all factors have three levels. According to the orthogonal test design composite yarn test program, the test factor levels are shown in Table 2 orthogonal test results are shown in Table 3. and the establishment of the composite yarn break fdM (Fuk elongation at break elongation iblish cracking! ! In the yarn, the fibers slip with each other. rt Table 2 Factor Levels Water Factors Composite Yarn Single Yarn Multifilament Tensile Tensile Coefficient Coefficient Coefficient No. 4 No. Fracture Strength F/cN Break Elongation Build Breaking Strength and Breaking Elongation The multivariate regression mathematical model between variables, and its regression equations are: Analysis of variance, the equations and coefficients are significant, in which the twist coefficient of the composite yarn and the twist coefficient of the single yarn are strong significant factors.
2.2 Effect of the composite yarn twist factor on the strength and elongation properties of the composite yarn For the compound strength equation, the twist coefficient of the composite yarn has a great influence on the breaking strength of the composite yarn. Under the condition that the single yarn twist coefficient is 460, the tension is 10 cN, and the multifilament twist coefficient is 0, the test is performed by changing the twist coefficient of the composite yarn, and the mathematical model between the (L) and the composite yarn twist factor (x). The regression equations obtained are: After analysis of variance, the equations and coefficients are significant. The relationship between the breaking strength, the elongation at break, and the twist coefficient of the composite yarn can be seen respectively for the composite yarns.
The relationship between the breaking strength of the composite yarn and the twist coefficient of the composite yarn is known from the relationship between the breaking elongation of the composite yarn and the twist coefficient of the composite yarn. The breaking strength of the composite yarn increases with the twist coefficient of the composite yarn within a certain range. After adding a certain value, the breaking strength decreased. This is due to the fact that the twisting of the composite yarn has two functions: on the one hand, the breakage of the composite yarn is generally a single yarn that has a small elongation at break and is first broken, so that the spun yarn and the filament are entangled with each other by twisting It effectively prevents the slipping and breaking of the spun yarn, and relatively increases the breaking strength of the composite yarn. The uneven intensity of the composite yarn is improved by the twisting effect, and it is also a factor that enhances the strength of the composite yarn. On the other hand, when the twist coefficient of the composite yarn exceeds a certain value, the twisting action causes pre-stressing of the fibers in the composite yarn, and at the same time, the fibers in the composite yarn have different angles with the axial direction of the yarn, so that the strength of the fibers is divided axially. As the force decreases, the breaking strength of the yarn in the composite yarn decreases with the large twist coefficient. Therefore, the effect of the twisting effect on the breaking strength of the composite yarn is the result of the unity of oppositeness of the above two aspects.
It can be seen that the elongation at break of the composite yarn is large and large with the twist factor. There is also a critical twist factor for the composite yarn breaking the composite yarn under tensile force. The composite yarn breaks under the condition that the pre-tension of the composite yarn is 5 cN, and the crack strength is within a certain range with the twist coefficient of the composite yarn. Increase the elongation caused by the maintenance of the composite yarn, the elongation of the yarn due to the external force, and the elongation due to the decrease of the twist angle of the yarn.
2.3 Influence of twist coefficient of single yarn on the strength and elongation performance of composite yarn The single yarn of small fracture elongation is always the first to break when the composite yarn breaks. Therefore, the strength of single yarn plays an important role in the strength of the composite yarn. When the composite yarn twist coefficient is 317. 5, the tension is 10 cN, and the multifilament twist coefficient is 0, the yarn twist factor is changed to test, and the breaking strength (F) and elongation at break of the composite yarn are established. The mathematical model between the rate (L) and the twist coefficient (x) of the single yarn obtained the regression equations as follows: the breaking strength and the elongation at break of the composite yarn are large and large with the twist coefficient of the single yarn. Because the twist direction of the composite yarn is opposite to that of the single yarn, the range of the twist coefficient of the single yarn is small, so the variation range of the twist coefficient of the single yarn is within the critical twist coefficient. Therefore, the relationship between the strength of the composite yarn and the twist coefficient of the single yarn is Not parabolic.
2.4 The effect of the combined effect of the twist coefficient of the single yarn and the twist coefficient of the composite yarn on the strength and elongation properties of the composite yarn is tested by changing the twist coefficient of the composite yarn and the twist coefficient of the single yarn, and the breaking strength (F) of the composite yarn is established. The mathematical model between the elongation at break a) and the twist coefficient (xi) of the single yarn and the twist coefficient of the composite yarn (x2) was obtained as follows: the breaking strength and breakage of the composite yarn within the critical twist coefficient range The elongation rate is large and large with the twist coefficient of the composite yarn and the twist coefficient of the single yarn. There is no interaction between the twist coefficient of the composite yarn and the twist coefficient of the single yarn.
Addition, after exceeding the critical twist factor, the breaking strength decreases; the elongation at break of the composite yarn is large and large with the twist coefficient of the composite yarn, and it has a positive linear correlation; the breaking strength, elongation at break, and single yarn of the composite yarn The twist factor shows a positive linear correlation. In actual production, the strength and elongation properties of the composite yarn can be predicted and controlled according to the derived regression equations of the breaking strength of the composite yarn, the elongation at break, the twist coefficient of the composite yarn, and the twist coefficient of the single yarn.
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