Macroporous gibbsite foams prepared from particle-stabilized emulsions using corn starch and agar as binders

作者：Tseng Wenjea J^*; Wu Pei Shan

来源：Ceramics International, 2012, 38(6): 4461-4465.

DOI：10.1016/j.ceramint.2012.02.020

• Porous material
• Gibbsite
• Emulsion
• Corn starch
• Agar

Corn starch and agar were used independently as a water-uptake binder in combination with anionic sodium dodecul sulfate (SDS) which modifies the hydrophobicity of cationic gibbsite platelets for preparation of air-in-water (a/w) gibbsite foams via a simple mechanical frothing. Contact-angle (theta) measurements revealed that the apparent theta decreased from partially hydrophobic (theta similar to 62 degrees) to more hydrophilic (theta similar to 47 degrees) when the corn starch was first added, leading to foams with a reduced stability. As the concentration of corn starch reached above similar to 8 vol.%, theta returned back to greater than 60 degrees rendering then a stable foam. On the other hand, theta was found to decrease from 57 degrees to 50 degrees when the agar concentration increased above a mere 0.16 vol.%. This gave rise to a pronounced drainage and coalescence of the foam, and a further increase of the agar concentration only led to a quick disappearance of the a/w bubbles. By tailoring the binder concentration, macroporous gibbsite foams were produced from the air- or freeze-dried wet foams, which typically consisted of packing void cells over a cell-size distribution of 50-400 mu m, a porosity ranging from 77% to 86%, and a three-point (green) rupture strength of up to 240 kPa.

• 出版日期2012-8