Cost‐Effective Fabrication of Hydrophobic Cellulose‐Based Foam Materials via Sizing Agent Modification

ABSTRACT Pulp molding, as an eco‐friendly packaging material, has been widely used in the logistics packaging industry. However, pulp molding materials are prone to moisture absorption and deformation in humid environments, which limits their application in liquid packaging or wet conditions. To address this issue, this study uses waste corrugated board fibers as raw materials and modifies the fibers with sizing agents, namely, maleic anhydride (ASA) and alkylketene dimer (AKD), via mechanical stirring foaming. The result is a cellulose‐based foam material with excellent hydrophobic properties. The prepared cellulose‐based foam material possesses the following outstanding characteristics: a density of only 0.182 g/cm 3 , a porosity of over 85%, and a compressive strength of up to 516 kPa, outperforming other cellulose‐based foam materials. Additionally, its elasticity is superior to that of traditional foam materials, with a water contact angle of 116.8°. The moisture absorption rate of the foam material modified with AKD is reduced from 29.68% to 2.38%, and after modification with ASA, the moisture absorption rate decreases to 2.6%. These results indicate the material's excellent hydrophobic performance. Notably, the sizing agent modification does not negatively impact the biodegradability of the cellulose‐based foam material, ensuring its environmentally friendly characteristics. This study provides a new direction for the application of pulp molding materials, particularly in humid environments and liquid packaging, showing promising application prospects.