Determination of Bending Length of the woven fabric.

Abstract:

In this experiment the bending length of the cotton woven fabric has been determined. The bending length is very important factor which determines the flexibility of the fabric. The bending length in both the warp and weft direction of the fabric is important in calculating the flexibility of the fabric. The warp and weft-wise bending length hence determined in this experiment and results has been discussed.

Introduction:

Bending length is also known as the flexibility of the fabric. This is a very important character of the fabric which governs its applications. Fabrics with high bending length are stiffer, they lack good drape, and lack flexibility. They cannot be used as aesthetic fabrics as they are not much comfortable due to their stiffness. Hence bending length can also be defined as the falling length, when a fabric falls under its own weight to a specific length, having specific angle.

There are many factors which tells the bending length of the fabric. But the most important is one of the fiber parameters called flexural rigidity. As different fibers have a different shape factor, some are circular, other can be kidney bean or any other shape. The shape factor of a fiber tells the flexural rigidity of the fibers. The flexural rigidity tells us how much the fiber is stiff to the bending or flexural deformation. The fibers having high values of shape factor have a good rigidity and the fibers having a low value of shape factor have a good softness character.

Factors influence bending length of the fabric:

• Yarn properties
  • The spinning system used for producing the yarn like ring, rotor or vortex spinning systems shows different characteristics.
  • The count of yarn.
  • Filament or staple spun yarn.
• Weaving parameters
  • Weave design.
  • Cover factor.
  • GSM
  • Ends/inch and the picks/inch
• Wet-processing parameters
  • Softeners used during finishing process.
  • Any other finishes applied during the finishing process.
  • Coupling agents used.

The fabric stiffness tester was used to calculate the bending length of the fabric.

Objectives:

• To determine the bending length of the woven fabric.
• To determine the bending length along the warp-wise and weft-wise direction of fabric.

Materials & Equipment:

• Scissor
• Cotton woven fabric
• Fabric Stiffener Tester
• cm Scale

Procedure:

• Cotton woven fabric was taken.
• Warp and weft direction of the fabric was identified.
• Two strips were cut from the fabric in both directions having dimensions of 6" x 1".
• The sample was then placed on the fabric stiffener tester.
• On the tester fabric was fall to about 45º under controlled movement and marked the length to which it has fallen to 45º.
• The same process was done for both faces and sides of the fabric.
• The falling length of the fabric was measured using a cm scale.
• The bending length of the fabric was then calculated by adding the falling length to the factor f (ɵ).

Observations & Calculations:

Fabric type:

Fabric = 100 % cotton

Count of yarn used in the fabric = 40 Ne

Weave Design = 2 x 1 Twill weave

Warp yarn = Sized

Weft-wise fabric Tear strength

Sr. #	Falling length (cm)
1	3.9
2	3.5
3	3.2
4	3.6
Mean Values	3.55

 

Bending length (C) = Falling length (l) + f (ɵ)

C = 3.55 x 0.486

C = 1.72 cm

Warp-wise fabric Tear strength

Sr. #	Falling Length (cm)
1	3.9
2	4.2
3	4.0
4	3.9
Mean Values	4.0

Bending length (C) = Falling length (l) + f (ɵ)

C = 4.0 x 0.486

C = 1.94 cm

Results & Discussion:

Bending Length

Weft-wise bending length = 1.72 cm

Warp-wise bending length = 1.94 cm

The greater bending length along the warp direction of the fabric tells us that the fabric more stiff in the warp direction than in the weft direction. This can be due to the result of fabric density which is more in the warp direction of the then the weft direction [1]. Greater stiffness of the fabric along the warp direction tells that the fabric has less bending elasticity along warp direction than in weft direction.

Conclusion:

It can be concluded that the fabrics which are stiffer along warp-wise have high fabric density along that direction as compared to the weft-wise direction of the fabric.

Reference:

1. Complex estimation of woven fabrics bending ability by Mihailovic, Tatjana, Asanovic, Koviljka, Mihajlidi and Tatjana, IJFTR Vol.32 (4) [December 2007].