Structural Properties of Foam-Formed Lignocellulosic Materials
Published: 2025
Publication Name: Construction and Building Materials
Publication URL: https://doi.org/10.1016/j.conbuildmat.2025.142401
Abstract:
This study provides a comprehensive understanding of the production of surfactant-assisted cellulose nanofibril (CNF)-reinforced thermomechanical pulp (TMP) fiber-based dry foams via the wet foam forming process. The synergistic interactions between TMP fibers, CNFs, and sodium dodecyl sulfate (SDS) surfactant to optimize foam stability during the wet foam forming process, and their impact on the properties of dry foam samples were comprehensively studied. Furthermore, investigating the effect of surfactant, CNFs, and TMP fibers on the foamability, foam volume stability, and foam liquid stability revealed information on the mechanisms by which various components affect the foam forming process. This understanding enabled tailoring and optimizing the properties of dry foams, such as density, inter-fiber distance, porosity, and fiber orientation. Microstructural analysis revealed that all these parameters significantly influenced foam thermomechanical properties. By controlling surfactant concentration, CNF content, and solids level, foams with densities ranging from 16 to 104 kg/m³ and porosities between 93.1 % and 98.9 % were produced. Foams of different formulations demonstrated low thermal conductivity (0.033–0.043 W/m.K), comparable to other reported biobased and synthetic foams. Foams exhibited excellent compressive strength, with formulations containing 10 % CNFs at 10 % solids with 2 g/L SDS meeting Type XI expanded polystyrene (EPS) insulation standard requirement (35 kPa at 10 % strain). Notably, the foams showed outstanding thickness recovery (up to 100 % after 24 h) and sound absorption coefficients matching or exceeding commercial petroleum-based foams, with maximum absorption achieved at 2500 Hz. Paper lamination further enhanced flexural properties, increasing modulus of rupture by 55–71 %. These fully biobased foams, which require no additional petrochemical binders, demonstrate the potential to effectively replace petroleum-based foams in building and packaging applications, offering a sustainable solution with robust performance.