Chemical modification routes of synthetic talc: Influence on its nucleating power and on its dispersion state
Résumé
New synthetic talcs were incorporated into a polyolefin matrix to prepare synthetic talc polypropylene (PP) nanocomposites via melt mixing. Different routes of physicochemical modifications of short range (cation exchange or silane grafting) or long range (compatibilizer) order were carried out to achieve an optimized dispersion state. A statistical TEM image analysis methodology was developed to evaluate more quantitatively the dispersion state of the talc particles within the PP matrix. Natural talc was taken as a reference in order to compare its nucleating power and its dispersion capacity with that of the synthetic talcs in the same grade of PP. Even though natural talc acts as the most efficient nucleating agent, the organophilic surface treatment enhances significantly the nucleating effect of the synthetic talcs. By coupling the incorporation of a compatibilizer with a suitable organophilic surface treatment, the synthetic talcs can be also better dispersed than their natural counterpart, giving rise to the formation of a heat shield that delays the thermal degradation of the filled matrix.