Abstract
Thermal behavior of nonionic surfactants, poly (oxyethylene) hexadecyl ethers, has been studied by thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), infrared absorption spectometry and elemental analysis. Curves of thermal degradation under the atmosphere of air and nitrogen were shifted to higher temperature with the increase in the number of the oxyethylene unit. The effect of the number of the oxyethylene unit on the activation energy of oxidation in the air was different from that in nitrogen atmosphere. Endothermic peak caused by fusion appeared in the range 30-60°C, whereas exothermic peak caused by oxidation and evaporation in the air appeared at 11O290°C. The temperature range for the appearance of exothermic peak caused by degradation in nitrogen was from 190 to 450°C. Entropy of fusion increased with the increase in the number of the oxyethylene unit and the increment per oxyethylene unit was 6.25 cal/deg 0mol. Upon heating, the poly (oxyethylene) chain in the poly (oxyethylene) hexadecyl ethers may be cleaved under oxygen to give several oxidation products.
