Overall Crystallization Behavior Of Polypropylene - Clay Nanocomposites: Bulk Crystallization And Spherulitic Growth: Effect Of Clay Content And Polymer/Clay Compatibility

CLAUDIO J. PEREZ, VERA A. ALVAREZ

JOURNAL OF APPLIED POLYMER SCIENCE

Wiley

Año: 2009 vol. 5 p. 3248 - 3260

0021-8995

The effect of clay nanoparticles on the overall crystallization (isothermal crystallization, spherulitic growth and non-isothermal crystallization) behaviour of polypropylene (PP) was studied by means of differential scanning calorimetry (DSC) and polarized light optical microscopy. In addition, the changes produced by the compatibility between the filler and the matrix were analyzed by using more hydrophobic clays or incorporating polypropylene grafted with maleic anhydride (PP-g-MA). Different models were used to predict the relative degree of crystallinity and several parameters were analyzed. A clear nucleating effect of clay nanoparticles were found on the experimental behaviour (induction time, half crystallization time, and overall crystallization time) and also deducted from the models parameters (Avrami exponent, rate constant, nucleation activity, activation energy). The effect was also related with the matrix/clay compatibility. In addition, the polarized light optical microscopy showed that the number of spherulites increased and their size decreased when clay was incorporated which is also an indication of the heterogeneous nucleating behaviour of such particles; being also faster the spherulitic growth and increasing Kg (the model parameter).