Investigations On Pyrolysis Of PVC Plastic With The Method Of Single Photon Ionization

We have researched the pyrolysis of PVC plastic in this paper used time of flightmass spectrometer and single photon ionization.In the first chapter, we have investigated the importance of PVC plastic and someconcepts of dioxin precursor and pyrolysis. We have reviewd the PVC pyrolysisproduct’s type and concentration and distribution at different temperature and differentgas atmosphere. Compared with other ionization methods in structure, applicable rangeand resolution of the instrument,we have expounded the single photon ionizationmethod’s advantage in plastic pyrolysis.In the second chapter, we have introduced our experiment device and experimentmethod. At first we have introduced five part of time of flight mass spectrometerincluding sample system, ionization source, mass analyzer, data acquisition system an-d vacuum system to maintain the normal work of the mass spectrometer. At secondwe have introduced optimize of the ionization source including pressure of three timesthe frequency of gas and the structure of gas cell. At last we have introduced theexperiment process in detail.In the third chapter, we have investigated three kinds of experiments. The first oneis that PVC particles pyrolysis products’ type, concentration, and the productdistribution in a vacuum environment along with the change of temperature. With theincrease of temperature, the types of pyrolysis products increased gradually and wecould get the mass spectrogram of ethylene, benzene, toluene, styrene andtetrachloroethylene which concentration is increased with the increase of temperature.The distribution is More and more uniform with the increase of temperature.Thesecond one is that PVC particles pyrolysis products’ type, concentration, and theproduct distribution in pure oxygen environment along with the change of temperature.We have found that we could hardly get the mass spectrogram of any product in lowtemperature compared with invaccum environment. The third one is that PVC plasticdistribution change with the change of oxygen concentration in250degreecentigrade. We have found that oxygen could change the product distribution tend todichloroethylene which toxic is less than vinylchloride. As the gas pressure is bigger,the phenomenon is more obvious. In the fourth chapter, we have investigated two kinds of experiments. The firstone is that PS particles pyrolysis products’ type, concentration, and the productdistribution in a vacuum environment along with the change of temperature. With theincrease of temperature, the types of pyrolysis products increased gradually most ofproducts’ concentration is increased with the increase of temperature. The second oneis that PS particles pyrolysis products’ type, concentration, and the product distributionin pure oxygen environment along with the change of temperature. We have found thatwe could hardly get the mass spectrogram of any product in low temperature comparedwith vaccum environment.The fifth chapter we have summarized the optimization experiment of ionizationsource and five kinds of experiments PVC and PS pyrolysis experiment in the type ofproduct, concentration and the product distribution.