| The thermal degradation behavior and hydrogen chloride (HC1) off experiments of PVC stabilized by2parts of barium stearate, methyltin mercaptide respectively and both the above via a1:1complexion were investigated by the means of non-isothermogravimetric analysis,Congo Red paper method and conductivity testing respectively.The result showed that either barium stearate or methyltin mercaptide alone had increased the thermal stability of PVC when both of the above heat stabilizer were added to the PVC respectively:the lowest decomposition temperature of PVC which added2parts of barium stearate was greater than203.6℃when the decomposition rate a is5%and the heating rate β is5℃/min;while the decomposition temperature of PVC which added2parts of methyltin mercaptide was greater than210℃. It is worth mentioning that when complexed the both heat stabilizers above via1:1,the decomposition temperature was greater than214℃when the heating rate P is5℃/min and the decomposition rate a is5%,it showed good thermal stability and synergistic effect.The mechanism functions and3thermal degradation kinetic parameters were obtained by Kissinger method, Flynn-Wall-Ozawa method(short for F-W-O), differentiation Achar-Brindly-Sharp (short for A-B-S) method and integration Coats-Redfern(short for C-R) method:the thermal degradation process of PVC which added2parts of barium stearate was controlled by A1.5(Avrami-Erofeev) mechanism and integral equation G(a)is-[1n(1-α)]2/3;while the thermal degradation process of PVC which added2parts of methyltin mercaptide was controlled by F1(Mample),and the mechanism was controlled by n=4(Reaction order).However, the mechanism functions were all both F2(second-stage reaction) when these three samples involved above at the deblocking stage calculated by double equal-double steps method.△S,△H,△G were calculated by means of calculation from peak temperature in the second decomposition,the AG were97.98,97.97and98.87KJ/mol respectively. |
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