The behavior which shows by textile material during bending is called flexural property. There are mainly three properties shown after bending a textile fiber.
1. Flexural rigidity
2. Bending recovery
3. Bending modulus
1.Flexural rigidity: Flexural rigidity is the stiffness of a textile fiber. It can be defined as the couple needed to bend a fiber.
Flexural rigidity = (1/4π) (ηET2/ρ)
Where, η = shape factor, E = specific shear modulus, T =linear density (Tex), ρ = density (gm/cm3)
Specific flexural rigidity: Specific flexural rigidity can be defined as the flexural rigidity of linear density.
Specific flexural rigidity = (1/4π)(ηE/ρ)
Where, η = shape factor, E = specific shear modulus, ρ = density (gm/cm3)
2.Bnding recovery : The recovery from a given curvature is called bending recovery.
Say, nylon shows 100% recovery from small curvature of 15D, where it shows 20% recovery from large curvature.
Unit = N-m2/ Tex.
3.Shape factor: shape factor is a number that indicates the shape of a fiber. Shape is expressed by “η”.
If, η = 1, it indicates the shape of fiber is round.
If, η > 1, it indicates the shape of fiber is increased.
If, η < 1, it indicates the shape of fiber is decreased.