Abstract
Polyamide 66 (PA66) containing phosphorus with flame-retardant property (FR-PA66) was synthesized with adipic acid hexamethylene salt and 2-carboxyethyl phenyl phosphinic acid as raw materials. The thermal degradation kinetics of FR-PA66 and PA66 were measured using a thermogravimetric analyzer, and the data obtained were analyzed with Flynn–Wall–Ozawa and Coast–Redfern methods. The results show that the activation energy (E a) of PA66 fabricated under different conditions will be different, while the mechanism functions of thermal decomposition remain the same. Comparing the limit E a value of PA66 with FR-PA66 at different stages of thermolysis, FR-PA66 keeps the initial thermolysis E a almost unchanged, reduces the middle thermolysis E a to 139.1 kJ mol−1, and increases the last thermolysis E a to 454 kJ mol−1, that is 223 kJ mol−1 higher than that of PA66 with 231 kJ mol−1. This result may be explained by the first cleavage of P–C bond and the formation of the carbonized protective layer. In addition, the most probable kinetic mechanism functions (F(α)) of thermolysis of FR-PA66 in three different stages were when the rate of decomposition (α) is lower than 0.4, F(α) = −ln(1 − α); when α is between 0.4 and 0.65, F(α) = [−ln(1 − α)]; and when α is beyond 0.65, F(α) = [−ln(1 − α)].
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