The Crystallization Kinetic And Thermal Decomposition Behavior Of Polyurethane

In this paper, the non-isothermal melting crystallization kinetics and thermal decomposition behavior of polyurethane are investigated by DSC and TG-DSC-FTIR-MS. DSC was used to study the non-isothermal melting crystallization process of polyurethane at the cooling rate of 2,4,6 and 8 k/min. Then the relationship between crystallization time and cooling rate was deeply analyzed, results showed that there is a strict exponential relationship between them.The non-isthermal melting crystallization kinetics of polyurethane was analyzed by methods of Avrami, Ozawa and Mo, according to these methods we found that the crystallization mechanism of polyurethane changed at different crystallization stage. Furthermore, we found that the crystallization rate incressed as the cooling rate incressed.The crystallization activation energy of polyurethane was determined by the methods of Kissinger, OFW and Friedman, while the results showd that the crystallization activation energy was different from each other and it was difficulty to confirm which one is more accurate. According to OFW and Friedman, we found that the crystallization activation energy were changed at different relative crystallization degree, this is another proof suggested that the crystallization mechanism changed with the proceeding of crystallization.The thermal decomposition behavior of polyurethane under different atmosphere environment was investigated by TG-DSC-FTIR-MS. According to the results of TGA we found that the exist of oxygen largely affect the decomposition process of polyurethane, at the same time we found that the decomposition cosist of three stagements and the first stagement was mostly in the same way, it suggested that the oxygen do not join the decomposition of first stagement. But with the help of FTIR and MS we found that the gas from the decomposition of polyurethane was extremely different under different atmosphere environment. The results showd that the gas production from inert atmosphere was consist of many kinds of hydrocarbon, amine, carbon dioxide, THF and some other organic compounds. In contrast, the gas production produced from the air atmosphere was very simple and it was nearly consist of carbon dioxide, water and little hydrocarbon.At last the thermal decomposition kinetic of polyurethane under inert atmosphere at theheating rate of 5,10,15 and 20 k/min was studied by non-linear multivariate regression method. And the results showd that the most probably kinetic model of polyurethane under inert atmosphere is A(?)B(?)C(?)D and the reaction mechanism of each step are all Fn(f(α)=(1-α)n)...