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ZD testing
In paper and paperboard the out-of-plane ZD properties are much lower than the in-plane properties. During end-use failure such as delimination is therfore common. In under to improve product performance it is therfore important to measure and improve out-of-plane (ZD) properites.
Purpose
To fully understand how paper materials behave in different process it is important to be able to measure the stress-strain behaviour in tension and compression.
To enable finite element simulation of converting operations or produce applications it is needed to have stress-strain descriptions of the material in each direction, which can be provided by the ZD tension and compression methods.
The testing of stress-strain behaviour also give values of pre-peak and post-peak properties, which have different importance in different applications.
Method
A setup where circular paper samples with area 10 cm2 have been developed at RISE Bioeconomy. The samples need to be glued to metal surfaces. It is important that the glue is much stronger and stiffer than the paper, and it should not penetrate into the paper. A procedure with plastic lamination and super glue have therefore been developed. The ZD specimens are tested in a MTS system, and displacement is measured with an extensometer.
Deliveries
Stress-strain curves can be determined. In addition, properties such as stiffness, strength and energy can be determined.