مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

The kinetic of the thermal degradation of rigid polyvinyl chloride (PVC) under nitrogen atmosphere was studied by bromometry titration at various temperatures (160190° C) in the presence of ethylene diamine tetra acetic acid (EDTA), 1,2 propane diol, benzoic acid, and phenol as thermal stabilizers. The rate of dehydrochlorination at 1% degradation (ROH) and the time required for dehydrochlorination to attain 1% conversion (toH) were used to assess the effect of the additives on the thermal susceptibility of PVC. It was found that the values of the ROH were relatively lower and the tOH were considerably higher than the value obtained in the absence of the additives. The degradation rate coefficients were determined from the rate of dehydrochlorinating. The following rate expressions R= k[PVClo.77[benzoic acidroAo, R= k[PVC]°·71[1 ,2 propane diolJ-1.78. R= K[PVClo.67[EDTAr2.18, and R= k[PVClo88[phenolro28 were obtained. The activation energies determined from the temperature dependence of the rate coefficients of the polymerיs degradation. The activation energies of the PVC degradation in the presence of EDTA, 1,2 propane diol, benzoic acid, phenol, and also in the absence of stabilizer were obtained 28, 27.5, 26.8, 26, and 24.5 kcalrnol", respectively. The results show that the order of increasing stabilizing effet was EDTA >1,2 propane diol>benzoic acid> phenol. The results also, reveal greater stabiliZing efficiencies of the investigated materials compared to non stabilizer