Investigating the hydrophilicity of phenol formaldehyde foams: Effects of synthesis parameters

Abstract

Open‐cell phenol (P) formaldehyde (F) foams are used for various applications such as hydroponic seed germination, flower arrangements, and sound insulation. This study investigated the influence of various parameters such as F/P molar ratios, blowing agents, surfactants, wetting agents, polymeric and inorganic additives, and oxidizing agents on the hydrophilicity of PF foams. Experimental results indicate that an F/P ratio of 1.8 was ideal for producing phenolic foams with good foam structure, uniform pore distribution, and favorable mechanical properties. A mixture of pentane and hexane at a mass ratio of 1:3 (wt/wt) used as a blowing agent resulted in a foam with the lowest density. With the optimal foaming catalyst (p‐toluene sulfonic acid) at a loading of 28 wt%, the foam exhibited a low density and excellent mechanical properties. A phenolic foam with a low density (39.27 kg/m3), high water absorption capacity (1210 wt%) and high open cell content (78.94%), was achieved by combining 6 wt% Tween‐80 as the surfactant and 3 wt% sodium dodecyl sulfate as the wetting agent. Additionally, 6.5 wt% loading of H2O2 led to a slight decrease in the foam density (38.46 kg/m3), but with a remarkable improvement in the wetting characteristics (water absorption capacity—2404 wt% and nearly 100% open cell content of the produced foam.