Relationships between macroscopic paper structure and water absorption behavior

Macroscopic structure of paper influences how paper behaves in many ways. In this research, the relationship between macroscopic paper structure and water absorption behavior was investigated. The structure of the handsheets made from commercial hardwood pulp was modified by varying basis weight, beating levels and wet press levels. The structural properties as well as the water absorption properties were measured. The results from contact angle measurement showed the same trend as the results from the automatic scanning absorptometer. Water absorption behavior greatly depends on surface structure. Smooth surface results in easy spread of a water drop and an increase in contact area. Any factors that change the paper surface structure will likely result in changes of its water absorption behavior as well. For surface chemistry, an increase in basis weight produced sheets with higher sizing agent (AKD) retention, thus causing higher contact angle of a water drop.