Billerud

Purpose and goal

Corrugated board boxes sometimes collapse with time when stacked in environments with varying air humidity. The study aimed to assess whether X-ray scattering can be used to detect structural changes in paper samples that are attributable to this mechano-sorptive creep effect. The conclusion was that structural changes are seen in the fiber material, but that further investigations are needed to decide whether they relate to mechano-sorptive creep.

Expected results and effects

The conducted measurements showed how both moisture and mechanical load cause structural changes in the tested paper samples at both the molecular and fibril level. Unfortunately, it has not been possible to firmly connect these effects to mechano-sorptive creep, in part because of the design of one of the detectors used in the trials. However, the first results are encouraging, and are expected to spurn continued studies of creep in paper materials using SAXS/WAXS techniques.

Planned approach and implementation

The project was a cooperation between BillerudKorsnäs, RISE, and DESY. A climate-controlled chamber containing a load-cell was built to allow paper samples to be subjected to mechanical load at controlled temperature and humidity conditions. SAXS and WAXS measurements were conducted at the P03 beamline at DESY, Hamburg, thus enabling the detection of structural changes in both the crystal and supramolecular structure of the fibers. Subsequent data analysis was conducted by RISE specialists.