Compatibilizer prevents the catalytic role of sepiolite in the thermal degradation of PP/Sep nanocomposites

One of the dubious aspects of polymer/clay nanocomposites is its thermal stability compared to the pristine matrix since we can find works indicating different directions with relatively similar materials. This work aims to evaluate the influence of the sepiolite content and the PP-g-MA compatibilizer presence in the polypropylene/sepiolite nanocomposites degradation. PP/Sep nanocomposites were prepared in a twin-screw extruder with 0.75-5 mass% of Sep and with or without 2.5 mass% of PP-g-Ma as a compatibilizer. Material characterizations were performed by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis (TGA). Morphology showed that the nanocomposites presented some needles agglomeration inside the polymer matrix, indicating the use of compatibilizer PP-g-MA was not enough for dispersion in the nanocomposites produced in this work. TGA results showed different results according to the nature of the atmosphere. In the oxidative atmosphere, the stability of nanocomposites was not significantly influenced by the sepiolite concentration, for concentrations lower than 1 mass%, and slightly influenced by the presence of PP-g-MA as a compatibilizer, while concentrations as large as 5 mass% of sepiolite showed a strong influence on the clay concentration. In the inert atmosphere, we observed the influence of the sepiolite concentration, decreasing the stability of the nanocomposite in the whole range of studied concentration. Regarding the presence of 2.5 mass% of PP-g-MA, all the formulations exhibit almost the same profile of mass loss, evidencing that the compatibilizer prevented the catalytic effect of the sepiolite in the thermal degradation of the nanocomposite.

Automated summary

This study evaluated the influence of sepiolite content and PP-g-MA compatibilizer on the degradation of polypropylene/sepiolite nanocomposites, revealing different effects under different atmospheres. The presence of sepiolite concentration and compatibilizer had varied effects on the stability of the nanocomposites, suggesting the need for further optimization in dispersing the nanofillers within the polymer matrix.