Effect of drying process on structure and property of polyaspartic acid resin

The effect of drying temperature on the physical and chemical structure and water absorbent behavior of polyaspartic acid resin were investigated via methods of infrared spectrum analysis and the electron microscope. The results show that: the heat treatment could result in a damage of the cross-linked bonds and a decrease of the cross-linked degree to the cross-linked polyaspartic acid resin. When the drying temperature exceeded 180°C, both backbone basic skeleton and side chain portions were also damaged heavily and gave off NH₃ in addition to the damage of the cross-linking portions. A relatively fast dehydrating rate at 40°C was in favor of the product with loose, uniform and nondestructive porous network structure to be obtained, which has big porosity and pore size. This kind of product has excellent water-absorbency and gel strength. The gel strength of PASP resin decreased with the increase of the drying temperature. The drying temperature has a greater effect on the swelling ratio and gel strength of the polyaspartic acid resin products with lower cross-linking degree than on that of the polyaspartic acid resin products with higher cross-linking degree.