Analysis of thermogravimetric data of blends of polyolefins with calcium carbonate treated with Lica 12

The objective of this work was to determine the kinetic parameters and the possible reaction mechanism in the polymer thermal decomposition using the software TGAnalyzer and analyze the effect of a titanate coupling agent (Lica 12) on thermal degradation of polyolefin blends, specifically polypropylene/high-density polyethylene (PP/HDPE), polypropylene/high-density polyethylene/ethylene-propylene copolymer (PP/HDPE/EPR) with 30 wt.% of calcium carbonate (CaCO3) untreated and treated with 1% Lica 12. Recycled high-density polyethylene (r-HDPE) was also included in the aforementioned blends. Dynamic thermograms were obtained for each blend sb that different methods could be applied for determining activation energy, reaction order and possible mechanism of decomposition. According to the results obtained for the activation energy (E-a), the addition of CaCO3 to the PP/HDPE/EPR blends does not significantly influence their thermal stability. The results showed that the optimum tiller concentration was 30 wt.%. Blends of PP/HDPE with treated CaCO3 exhibit E-a values higher than those of the blends containing EPR, which means that Lica 12 has an accelerating effect on the decomposition of these blends with EPR. In addition, the recycled material was found to decrease activation energy of the blends. Morphological observations help us determine that Lica 12 influences thermal stability, by increasing activation energy, with a better dispersion of the blend components. For all the samples studied in this work, the reaction mechanisms are diffusion and Limiting surface reaction between both phases, in three dimensions and three ways (D3 and R3). (C) 2001 Elsevier Science Ltd. All rights reserved.