| This paper uses the enhancement of nano-titanium dioxide?NT?,Premixed and dense processing technology,a polyvinyl chloride film containing an organic tin/cerium metal soap/dipentaerythritol/NT composite stabilizer was prepared,and using Congo red test,oven static aging method,non-isothermal thermogravimetric?TG-DTG?,differential scanning calorimetry?DSC?,thermogravimetric infrared?TG-FTIR?and dynamic thermomechanical analysis?DMA?,For?A?organic tin/cerium metal soap/dipentaerythritol/NT?0.5:0.5:1.0:5.0:1.0?coupling agent?parts?,?B?organic tin/cerium metal soap/dipentaerythritol?0.5:0.5:1.0 parts?,?C?organic tin/cerium metal soap?0.5:0.5 parts?,?D?organic tin?1.0 parts?and?H?blank?no stabilizer?under the action of different composite stabilizers PVC film was characterized and tested for thermal stability.The possible thermal degradation mechanisms of?A?and?B?PVC films were proposed separately;The main contents of the research are:?1?The experiment using Congo red at 195?showed that the initial bluening time of different PVC samples was?A?49 min,?D?32 min,?B?30 min,?C?24 min and?H?6 min,respectively.It can be seen that nano-titanium dioxide?NT?has significant enhanced stabilizing effect on organotin,cerium metal soap and dipentaerythritol and PVC composite system;The static aging test of the oven showed that the heating blackening sequence of the PVC film at 195?was?A?200 min,?B?150 min,?D?130 min,?C?100 min and?H?20 min,respectively;If the temperature T1%?°C?when the weight loss of the sample is 1%is taken as one of the criteria for evaluating the thermal stability of the PVC film,the temperature at which the weight loss is 1%is?A??233.8??,?B??226.6??,?D??210.8??,?C??202.0??and?H??175.7??.It can be seen that the heat resistance of the PVC samples containing the composite stabilizers?A?,?B?,?D?and?C?was significantly better than that of the blank?H?.?2?Through TG-DTG,it is shown that the thermal degradation stages of different PVC blends can be roughly divided into two stages,the first stage is 170?-375?,the second stage is 375?-550?,the first stage the sample weight loss?decomposition amount?is greater than the weight loss?decomposition amount?of the second stage.The thermal degradation products and volatiles in the thermal degradation process of PVC were analyzed by thermogravimetry-infrared?TG-FTIR?technique.It is known that the thermal degradation products of PVC blends under different mixing stability are basically the same.The main gases released are H2O,CO2,aromatic hydrocarbons?benzene?,hydrocarbons?CH4?,HCl,esters,and chlorinated hydrocarbons.From the 3D spectra of TG-FTIR,it can be seen that the relative absorption peak intensity of CO2 produced by thermal degradation of different PVC blends varies significantly with the different stabilizers.?3?Using the Friedman?FR?method,the Kissinger-Akabira-Sunose?KAS?method,the Flynn-Wall-Ozaw?FWO?method and the Kissinger method,The thermal degradation kinetics of PVC films containing?A?and?B?were calculated by equal conversion method.Obtained the apparent activation energy E of the first and second stages of thermal degradation,The PVC films containing?A?and?B?are 131.3,239.9kJmol-1 and 120.7,221.8kJmol-1,respectively.It can be seen that the apparent activation energy of thermal degradation of?A?PVC film is significantly higher than that of?B?PVC film after adding nano-titanium dioxide particles,which leads to the enhancement of thermal stability of the sample.?4?The most probable kinetic mechanism of thermal degradation of PVC films containing?A?and?B?in the first stage was deduced by Master-plot principal diagram method.It was inferred that?A?there was a F1 mechanism model and?B?there was a R2 mechanism model.Figures[29]Tables[31]References[96]... |
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