TAPPI T 566 om-21 PDF

This test method covers a procedure used to measure the resistance to bending of papers which are of low grammage, or high flexibility, or both, and which exhibit bending stiffness in the range of 0 to 10 Taber stiffness units.

This test is used to determine the bending moment required to deflect the free end of a 38 mm (1.5 in.) wide vertically clamped specimen 15 from its center line when the load is applied 10 mm (0.39 in.) away from the clamp. The resistance to bending is calculated from the bending moment.

The instrument used in this test method is identical to that described in TAPPI T 489 Bending
Resistance (stiffness) of Paper and Paperboard (Taber-type tester in basic configuration), used in the modified configuration described in section 6.2.4. Preparation of Apparatus. The 0-10 unit test range magnifies the scale indication ten times so that flexible materials can be tested below the standard range of the pendulum (0-100 Taber stiffness units).

Test results obtained using the Taber-Type Tester as described in this test method have been reported to be as much as 40% different from those obtained using TAPPI T 489, and this test method must not be used where TAPPI T 489 is specified.

Other procedures for measuring bending resistance include TAPPI T 535 Bending Stiffness of Paper and Paperboard (Resonance Length Method); TAPPI T 543 Bending Resistance of Paper (Gurley-Type Tester); TAPPI T 556 Bending Resistance of Paper and Paperboard by Single-Point Bending Method; and TAPPI T 836 Bending Stiffness, Four Point Method. TAPPI T 535 has been classified as a Classical Method.