Exceptional pore size distribution in foam-formed fibre networks

Abstract

Foam forming leads to sheet structures with exceptional volume of large pores. The link between fibre network structure and foam properties is investigated by comparing pore structure with measured bubble-size distribution. In foams produced by mechanical mixing, higher rotor speed leads to smaller average bubble size, whereas the effects coming from air content and surfactant are smaller and non-systematic. A significant drop in the average bubble size is seen when mixing fibres to foam. In sheets made with foam forming, there are more large pores compared to the water formed sheets. The size of these pores is affected by the sizes of the bubbles in the foam. Overall, pore size distribution is more strongly affected by the fibre type than by small changes in bubble size distribution.

A unique microstructure of the fiber networks deposited from foam–fiber suspensions

“…[11], the area-weighted bubble sizes followed a Gaussian distribution both for the pure foam and the foam-fiber suspension. Table 4 shows the parameters of the Gaussian distributions that fitted these distributions.…”

“…To this end, porous structures obtained by foam forming are compared with those obtained using a water suspension. It has been already suggested that the porous structure obtained with foam forming could differ significantly from that obtained with a traditional water forming [10,11]. However, the two forming methods have been previously compared only as separate technologies, i.e., without any attempt to avoid the contribution of the density of the final (or targeted) structure.…”

3D-oriented fiber networks made by foam forming

“…Recently, foam forming was studied extensively to develop the understanding of foam-fiber interactions (Al-Qararah et al 2012Lappalainen and Lehmonen 2012;Lappalainen et al 2014;Mira et al 2014) and also to find the potential applications of this technology in papermaking Lehmonen et al 2013;Poranen et al 2013) as well as other specialty products, e.g., filters and insulators (Cervin et al 2013;Jahangiri et al 2014). Foam was introduced to the paper industry already in the mid-1960s.…”

Experimental results on the flow rheology of fiber-laden aqueous foams

“…After a long silent period, foam-coating [13,14] and foam-forming are now attracting increasing interest in paper industry [15][16][17][18][19][20]. The use of foam allows the inclusion of a wide variety of alternative raw materials, such as nanoparticles [21], nanocellulose [22] and long flexible fibers.…”