BIODEGRADABLE POLYMER/CLAY NANOCOMPOSITES: PREPARATION AND CHARACTERIZATION

LEANDRO LUDUEÑA; ANALÍA VAZQUEZ; JOSÉ KENNY; VERA ALVAREZ

Ciudad de Heredia, Costa Rica

Simposio; XII SIMPOSIO LATINOAMERICANO DE POLÍMEROS, SLAP 2010; 2010

The isothermal crystallization process of Polycaprolactone (PCL)/clay nanocomposites, was studied. The reinforcement phase lowered the time to appear the first crystal nucleus (known as induction time) and increased the global crystallization rate in comparison with the neat PCL. The spherulitic growth was analyzed by optical microscopy. The clay produced more and bigger spherulites. These results were strongly dependent on the dispersion degree of the clay. The experimental bulk crystallization behaviour was modeled by the Avrami equation and the spherulitic growth by secondary nucleation theory of polymer crystal growth obtaining good agreement between them. The effect of temperature and clay/polymer compatibility on creep behaviour was also analyzed. The Burgers model was used to establish a correlation between the experimental behaviour and the nanocomposite morphology. The Findley power law model was also employed. Time-temperature superposition principle was used to predict the long-term behaviour based on the short-term experimental data. Both, experimental curves and models demonstrated that the incorporation of the clay produces a significant improvement on the creep resistance. This improvement was even more important for well-dispersed nanocomposites related to the great enhancement of the elastic behaviour. Several organo-modified clays were used to find the best filler for PCL. Morphological and mechanical analysis revealed that PCL/C20A nanocomposites exhibit the best performance, being C20A montmorillonite modified with dimethyl, dehydrogenated tallow, quaternary ammonium. The effect of changing the twin screw extruder processing parameters and different post-processing methods (compression moulding, injection moulding and calendering) on the morphology and mechanical properties was also analyzed. The degradation behavior in soil of these materials was studied. Best dispersed clays and high contents of them delayed the degradation process of the neat matrix.