Thermogravimetric study of medical transfusion tube(MTT) waste containing polyvinyl chloride(PVC) was carried out using the thermogravimetric analyser(TGA) with N2, at different heating rates of 5, 10, 20, 30, 50 °C/min. The purpose is to obtain pyrolysis characteristics and kinetic parameters of medical waste. The experimental results indicate that the pyrolysis behavior of the MTT sample is in agreement with its main ingredient of PVC, appearing two stair stepping stages. The influence of the additives in MTT on pyrolysis behavior was also revealed, which could improve MTT pyrolysis at lower temperature in the first stage, and cause obvious unsmoothness and asymmetry of the second DTG peak. Four n-order kinetic models of Coats-Redfern, Ozawa, Kissinger and Freeman-carroll were used to get the kinetic parameters. Furthermore, a novel "two-step four-reaction model" was established to simulate the whole continuous process. The different methods and the kinetic parameters thus obtained were discussed and compared with each other in literatures. The reasons of deviation among kinetic values were tried to be elucidated. The new established model could more satisfactorily describe the pyrolysis process of MTT, being more mechanistic and conveniently serving for the engineering.
Thermogravimetric study of rubber compositions(operating glove and catheter)in medical waste was carried out using the thermogravimetric analyser(TGA),at the heating rate of 20°C/min in a stream of N2.The results indicate that the decomposition process of operating glove appears an obvious mass loss stage at 250 485°C,while catheter has two obvious stages at 240 510°C and 655 800°C,respectively;both samples present endothermic pyrolysis reaction;the decomposition of operating glove and the first mass loss stage of catheter are in agreement with natural rubber pyrolysis;the second mass loss stage of catheter corresponds to CaCO3decomposition.Based on the experimental results,a novel two-step four-reaction model was established to simulate the whole continuous processes,which could more satisfactorily describe and predict the pyrolysis processes of rubber compositions,being more mechanistic and conveniently serving for the engineering.
