Effect of Twist on Yarn Strength and Fabric Properties
Twist is an important factor in finished consumer goods. It determines the appearance as well as the durability and serviceability of a fabric.
Twist can be measured by the number of twisting rounds per unit length in each stage of manufacture. This figure can be used to denote the amount of twist present in a thread at that stage.
Tensile Strength
A fabric produced from a high-twisted yarn will have higher tensile strength than one produced from a low-twist yarn. This is because staple fiber yarns increase in tensile strength as twist increases until they reach a twist level called the ‘optimum twist’.
Filament yarns, on the other hand, become stronger untwisted and decrease in tensile strength as twist increases. In addition, filament yarns tend to have a lower twist multiplier than staple fiber yarns.
The effect of twist on tensile strength and fabric properties is significant because it can determine how well a fabric will hold up over time. It can also influence how comfortable a garment will be to wear.
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Elasticity
In a yarn, twist influences both its strength and fabric properties. It has an effect on tensile, bending, shear, buckling and compression.
Moreover, it influences the fiber properties, such as crystallinity, amorphous regions and orientations. These effects can be used to produce fabrics with the desired mechanical properties.
This study investigates the impact of variations in twist coefficient on tensile strength and elongation of wrapped polyester (PET) yarns twisted with spandex fibers. During the twisting process, the thermal treatment temperatures as well as twist coefficients controlled by rotor speed were varied.
The resulting wrapped PET/spandex yarns showed similar tensile strengths and elongation properties to those of the unwrapped yarns. This suggests that the influence of twist on tensile strength and elongation is governed by a specific set of parameters, distinctive to the material, composition, yarn count and processing.
Shrinkage
Twist plays a significant role in determining the properties of finished consumer goods. It determines the appearance, strength and smoothness of yarns as well as their elasticity and durability.
Twisted continuous filament yarns are commonly used in textile applications because they have a high fiber density and are easy to handle. However, increased twist can reduce the strength of a continuous filament yarn as the individual fibers tend to weaken at higher levels of twist.
Yarn twist is also a major factor in the dimensional stability of a fabric. Shrinkage is a quality parameter that is tested at many different stages in the production process and it is crucial for the fabric to be shrink-free when it leaves the factory.
Tensile Linearity
Twist plays an important role in yarn strength, elongation and fabric properties. It is well known that a higher twist increases the tensile strength of the yarn in a twisting machine.
However, the effect of twist on tensile properties is not entirely linear and depends on various factors such as fineness, loading rate and length. This is a difficult problem to study since a large number of factors affect the tensile response and therefore the design of the experiments.
Moreover, the fibers cross-section and porosity of the yarn also play an important role in determining tensile properties such as water permeability. The woven fabrics with 920 TPM weft yarn had the highest water permeability values as they had a less hairy surface and more porous structure.
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Water Permeability
Twist is the spiral arrangement of the fibres around the axis of the yarn in a yarn twisting machine, it binds the strands together and contributes to the strength of the end product. The number of twists per unit length will define the appearance and strength of the final product.
It also changes the collective structural form, physical and mechanical properties of the fibres. Tightly twisted fibres can create a lighter and more breathable fabric, which is perfect for hot weather and summer wear.
Increasing the amount of twist in a fibre can improve its durability, make it slightly stronger and reduce its susceptibility to pilling. It can also help to prevent the stitches from breaking, making them easier to work with.
