The influence of fines, fibre contact and grammage on the free shrinkage of handsheets

摘要

Experiments were carried out to investigate the influence of fines and grammage on the free shrinkage of handsheets. In agreement with results from the literature, we find that free shrinkage increases linearly with fines content. Further, we show that in the presence of fines, free shrinkage increases with grammage. Using theory to guide our interpretation of the data we show that when fines are present, free shrinkage increases linearly with fractional contact area. The observed increase with grammage is consistent with fibres at the surfaces of the sheet being less efficient at transferring shrinkage forces to the network than those in the bulk. Although the water retention value of fines is greater than that of fibres, our analysis suggests that this is not the major cause of the influence of fines on free shrinkage.