摘要 |
An exothermic gel polymerization process conducted in the presence of water is initiated at a low temperature, is held for most of the process at a higher temperature by including in the medium a particulate heat sink material, such as sodium sulphate decahydrate, that is substantially insoluble in the medium and which undergoes an endothermic phase change and is then allowed to rise to a higher temperature. Either as a result of the endothermic change, or as a result of a subsequent exothermic change, at the end of the process the heat sink material is again solid particulate material substantially insoluble in the medium and so the product is a dispersion of the material in a polymer gel. The polymer is water soluble. |