Research progress on the application of tristate water in preparation of starch‐based foaming materials

Research on the preparation of starch-based degradable foams by adding simple raw materials and using simple processes meets the requirements of modern society and market demand. Water is the most common raw material in daily life, its triple transformation is easy to achieve, and it has an important effect on many aspects of the starch foaming process. This paper presents the research results on the preparation of starch-based foaming materials using water as an important raw material, summarizing the mechanism of the action of solid-liquid gaseous water in the plasticization, foaming, hydrophobic, and swelling processes. Water vapor fumigation of starch materials uses high temperatures to induce the inversion (or dehydration) of the hydroxyl groups distributed on the surface, reducing the water sensitivity of the starch foam surface. Finally, the development trend is analyzed and foreseen, in order to provide new ideas for the development of low-cost methods to prepare degradable and environmentally friendly packaging materials.