Читать книгу High-Performance Materials from Bio-based Feedstocks - Группа авторов - Страница 53

The formation of Starbon, irrespective of the nature of the polysaccharide, has three distinct stages (gelation, drying, and pyrolysis). First, gelation of the polysaccharide takes place in water to swell the material (starch, for example, exists in nature as densely packed granules and functions as an energy source) to produce a hydrogel. The gelation is promoted by a combination of temperature and shear forces, which aid in breaking up the tightly packed grain, allowing some of its contents to move outwards, creating porosity. A subsequent step is a retrogradation, where the gel is allowed to ‘rest’ at 4 °C for approximately 24 hours. This causes slight structural changes and stabilisation.