The clays modified in the laboratory, CBPAS and CPEIA, show a considerably lower effect on the PC degradation. The different behavior of these clays, in relation with C15, can be explained by taking into account that the chemical modifications of CBPAS and CPEIA do not contribute to the generation of acidic sites during the melt processing of the nanocomposites. On the other hand, the TEM images reveal a poor dispersion of CBPAS and CPEIA into the polymer, as well as the presence of a dark impurity around the clay in the corresponding composites (see Fig. 3). This impurity can be explained by the presence of degraded rests of the chemical modification of these clays, which are only partially eliminated during the melt processing of the nanocomposites at 250 °C. These degraded rests can hinder the dispersion of the clays into the polymer and the good contact necessary for the catalytic effect on the polycarbonate degradation.
The above results indicate that the nature (and especially some degradation processes) of the chemical modification of the clays plays a main role in the degradation of PC during the melt processing of the nanocomposites. Thus, the above results confirm that the organic modification and the amount of the layered silicate must be carefully selected in order to minimize the polymer degradation during the melt processing of the nanocomposites.