Foam forming revisited Part I. Foaming behaviour of fibre-surfactant systems

• The foaming properties of typical chemithermo-mechanical (CTMP) and kraft pulp paper making formulations in the presence of a series of surfactants were investigated using a lab-scale foaming set up. Foamability, foam stability, and bubble size distribution of the generated foam-fibre systems were measured. The foaming behaviour of the fibre/surfactant systems was found to be dependent on the surfactant concentration. Foams fulfilling the target requirements of air content (ca. 65% v/v air) and average bubble size (25 to 75 μm in radius) were obtained with all the seven surfactants tested. Three of the surfactants were found to allow for a rapid foaming in the system, namely sodium dodecyl sulphate (SDS), a commercial mixture of alkyl and ethoxylated alkyl sulphates, (MixSAES) and a commercial mixture of short chain alkyl glucosides (C8/C10Gluc). The rapid foaming is believed to be an intrinsic property of mixtures of surfactants with the right molecular structures and in the right proportion with respect to each other. On the other hand, the minimum surfactant concentrations required to reach the target foam volumes were lowest for surfactants with an anionic character. Further, the type of pulp fibre and the presence of GCC in the surfactant/pulp formulation were found to have very little effect on the foaming performance of the suspensions.

Nyckelord

Anionic surfactants

Aqueous foam

Foam stability

Foam-fibre mixture

Foamability

Non-ionic surfactants

Fibers

Kraft pulp

Mixtures

Sodium compounds

Sulfur compounds

Aqueous foams

Bubble size distributions

Commercial mixtures

Foaming properties

Sodium dodecyl sulphate

Surfactant concentrations

Chemimechanical Pulping

Foaming

Kraft Pulping

Paper Making

Surfactants

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