Vortex spinning can be viewed as a refinement of jet spinning or a
natural development in the fasciated yarn technology. Like in all other
fasciated yarns, the structure of vortex yarn consists of a core of
parallel fibers held together by wrapper fibers. This has been revealed
by examining an untwisted yarn sample under the Scanning Electron
Microscope. Subsequently the physical properties of vortex and air jet
yarns produced from different polyester cotton blends were compared.
Results indicated that vortex yarns have tenacity advantages over air
jet yarns particularly at high cotton contents.
3.0 Introduction
The yarn structure is one of the primary factors which control the properties of spun yarns. Vortex spun yarn has a two part structure. This can be simply revealed by untwisting a vortex yarn by hand. Because the yarn is a relatively small component a more reliable conclusion requires visual help. As a first step of this study a piece of vortex yarn was untwisted and viewed under the Scanning Electron Microscope. Since none of the conventional twist measurement methods are suitable for vortex spun yarns, untwisting was performed with the aid of an optical microscope, and the completion of untwisting was visually confirmed. SEM pictures agreed that vortex yarns consist of two distinctive parts: core and sheath. In the pictures the sheath part appeared looser due to removed twist (Figure 1).
Only limited information was obtained through SEM pictures. In order to broaden our knowledge about this new and fascinating yarn technology the next logical step was to compare the properties of airjet and vortex yarns. Although both systems are used to spin fasciated yarns, no work has been reported to date regarding the difference between these yarns. A study was conducted to reveal the difference between the properties and structure of the vortex and air jet spun yarns. In the first part of this study the properties of vortex and airjet spun yarns made from various PES/Cotton blends were compared. In the second part, vortex and air jet yarns produced from three different blends of cotton and black polyester fibers were visually examined under an optical microscope.
Materials and Methods
For the first part of the study, five different blend ratios: 83/17, 67/33, 50/50, 33/67, and 17/83 were obtained from polyester and carded cotton slivers by blending them on the draw frame. Table 1 shows the properties of cotton and polyester fibers used
in this study. After three passages of drawing, slivers were transferred to MJS and MVS machines. Table 2 displays the process parameters used on MJS and MVS systems.
The spinning of pure cotton and the polyester/cotton blend with 83 % of cotton ratio was not possible for MJS system. In fact, when the blend ratio of polyester was less than 50%, it was very difficult to spin yarn with an acceptable end break level on this system. MVS system successfully produced yarns from 100% polyester and polyester/cotton blends, but spinning 100% cotton was not successful. One possible reason is the high short fiber content of cotton slivers.
The quality parameters of the produced yarns were evaluated on Uster Evenness Tester, Uster Tensorapid (Testing speed 250 mm/m) and Uster Tensojet (Testing speed 400m/m).
In the second part of the study, in order to compare the basic structure of vortex and air jet yarns, blended yarns were produced from three different blends of black polyester (1.7 den, 1.5 in) and cotton fibers (4.1 mic., 0.91 in) (blend ratios: 33/67, 50/50, 67/33). These yarns were examined under an optical microscope to find out any possible tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Besides the visual examination of yarn structure, the evenness and tensile properties of these yarns were tested on the Uster Evenness Tester and Uster Tensorapid, respectively.
Results and Discussion
An analysis of variance (ANOVA) was performed to determine the statistical significance of any observed differences between the properties of vortex and airjet spun yarns. The ANOVA revealed that yarns made by the MVS had superior evenness, fewer number of thick places and lower hairiness values compared to those made by the MJS (Figure 2 and Table 3). Vortex yarns also presented higher tenacity values for every blend ratio except the 100% polyester case, and as the cotton content increased in the blend, the difference enlarged (Figure 3 and Table 4). For 100% polyester yarn, on the other hand, the tenacity values of vortex and airjet yarns did not differ significantly. In the case of yarn elongation the outcome was the opposite. Vortex yarns exhibited lower elongation values compared to airjet yarns. Unsurprisingly, this led to an insignificant difference in their work of rupture values.
The unique yarn structures associated with these yarns are a possible reason for the difference in yarn quality parameters. The higher tenacity values of vortex yarns can be attributed to the higher number of wrapper fibers in these yarns. The number of wrapper fibers is critical to yarn strength since they hold the internal parallel fiber bundle tightly together. In air jet spinning edge fibers ultimately produce wrapper fibers, and the number of edge fibers depends on the fibers at the outside [1,2]. On the other hand, in vortex spinning the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle [3]. This results in a higher number of wrapper fibers in the yarn. One possible explanation for the reduction in elongation is the decrease in fiber slippage due to better grip by wrapper fibers. Possibly the drop in hairiness values is another result of better wrapping.
Visual comparison of vortex and air jet yarns showed that there were no apparent tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Although this study did not provide enough information to reach a consistent conclusion, examination of these yarns under the microscope showed that vortex yarns have more ring like appearance and a higher number of wrapper fibers compared to air jet yarns (Figure 4.)
The results from the evenness and tensile testing agreed with the earlier findings that vortex yarns had better evenness and tenacity values compared to air jet yarns (Figure 5 and Figure 6.)
Conclusion
This study revealed that MVS spinning technology is favorable for cotton spinning and produces a yarn with more ring like appearance compared to MJS spinning technology. However, more in depth study is required to understand the structure of vortex yarns.
3.0 Introduction
The yarn structure is one of the primary factors which control the properties of spun yarns. Vortex spun yarn has a two part structure. This can be simply revealed by untwisting a vortex yarn by hand. Because the yarn is a relatively small component a more reliable conclusion requires visual help. As a first step of this study a piece of vortex yarn was untwisted and viewed under the Scanning Electron Microscope. Since none of the conventional twist measurement methods are suitable for vortex spun yarns, untwisting was performed with the aid of an optical microscope, and the completion of untwisting was visually confirmed. SEM pictures agreed that vortex yarns consist of two distinctive parts: core and sheath. In the pictures the sheath part appeared looser due to removed twist (Figure 1).
Only limited information was obtained through SEM pictures. In order to broaden our knowledge about this new and fascinating yarn technology the next logical step was to compare the properties of airjet and vortex yarns. Although both systems are used to spin fasciated yarns, no work has been reported to date regarding the difference between these yarns. A study was conducted to reveal the difference between the properties and structure of the vortex and air jet spun yarns. In the first part of this study the properties of vortex and airjet spun yarns made from various PES/Cotton blends were compared. In the second part, vortex and air jet yarns produced from three different blends of cotton and black polyester fibers were visually examined under an optical microscope.
Materials and Methods
For the first part of the study, five different blend ratios: 83/17, 67/33, 50/50, 33/67, and 17/83 were obtained from polyester and carded cotton slivers by blending them on the draw frame. Table 1 shows the properties of cotton and polyester fibers used
in this study. After three passages of drawing, slivers were transferred to MJS and MVS machines. Table 2 displays the process parameters used on MJS and MVS systems.
The spinning of pure cotton and the polyester/cotton blend with 83 % of cotton ratio was not possible for MJS system. In fact, when the blend ratio of polyester was less than 50%, it was very difficult to spin yarn with an acceptable end break level on this system. MVS system successfully produced yarns from 100% polyester and polyester/cotton blends, but spinning 100% cotton was not successful. One possible reason is the high short fiber content of cotton slivers.
The quality parameters of the produced yarns were evaluated on Uster Evenness Tester, Uster Tensorapid (Testing speed 250 mm/m) and Uster Tensojet (Testing speed 400m/m).
In the second part of the study, in order to compare the basic structure of vortex and air jet yarns, blended yarns were produced from three different blends of black polyester (1.7 den, 1.5 in) and cotton fibers (4.1 mic., 0.91 in) (blend ratios: 33/67, 50/50, 67/33). These yarns were examined under an optical microscope to find out any possible tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Besides the visual examination of yarn structure, the evenness and tensile properties of these yarns were tested on the Uster Evenness Tester and Uster Tensorapid, respectively.
Results and Discussion
An analysis of variance (ANOVA) was performed to determine the statistical significance of any observed differences between the properties of vortex and airjet spun yarns. The ANOVA revealed that yarns made by the MVS had superior evenness, fewer number of thick places and lower hairiness values compared to those made by the MJS (Figure 2 and Table 3). Vortex yarns also presented higher tenacity values for every blend ratio except the 100% polyester case, and as the cotton content increased in the blend, the difference enlarged (Figure 3 and Table 4). For 100% polyester yarn, on the other hand, the tenacity values of vortex and airjet yarns did not differ significantly. In the case of yarn elongation the outcome was the opposite. Vortex yarns exhibited lower elongation values compared to airjet yarns. Unsurprisingly, this led to an insignificant difference in their work of rupture values.
The unique yarn structures associated with these yarns are a possible reason for the difference in yarn quality parameters. The higher tenacity values of vortex yarns can be attributed to the higher number of wrapper fibers in these yarns. The number of wrapper fibers is critical to yarn strength since they hold the internal parallel fiber bundle tightly together. In air jet spinning edge fibers ultimately produce wrapper fibers, and the number of edge fibers depends on the fibers at the outside [1,2]. On the other hand, in vortex spinning the fiber separation from the bundle occurs everywhere in the entire outer periphery of the bundle [3]. This results in a higher number of wrapper fibers in the yarn. One possible explanation for the reduction in elongation is the decrease in fiber slippage due to better grip by wrapper fibers. Possibly the drop in hairiness values is another result of better wrapping.
Visual comparison of vortex and air jet yarns showed that there were no apparent tendencies of cotton or polyester fibers to become either wrapper or core fibers in blended yarns. Although this study did not provide enough information to reach a consistent conclusion, examination of these yarns under the microscope showed that vortex yarns have more ring like appearance and a higher number of wrapper fibers compared to air jet yarns (Figure 4.)
The results from the evenness and tensile testing agreed with the earlier findings that vortex yarns had better evenness and tenacity values compared to air jet yarns (Figure 5 and Figure 6.)
Conclusion
This study revealed that MVS spinning technology is favorable for cotton spinning and produces a yarn with more ring like appearance compared to MJS spinning technology. However, more in depth study is required to understand the structure of vortex yarns.