Compósitos pead/quitosana preparados por fusão. Influência do teor de compatibilizante e de antioxidantes.

Abstract

This work involves the preparation and characterization of high density polyethylene (HDPE) composites and chitosan, compatibilized with polyethylene grafted with maleic anhydride and additivated with the antioxidants butylhydroxyanisole and butylhydroxytoluene. The composites were prepared in an internal mixer to evaluate their rheological, morphological, thermal and mechanical characteristics. According to the results of rheometry, with the incorporation of chitosan to HDPE, even at the highest levels (25%), no evidence of degradation was observed during the processing time (10 min) and temperature (180°C), indicating that the composites are thermally stable. However, the viscosity increased with the presence of chitosan and this increase was more expressive with the addition of the compatibilizing agent, due to the greater interaction between the phases, as suggested by the morphology observed by optical microscopy (OM) and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) showed that thermal transitions and crystallinity were not significantly altered with the incorporation of chitosan, compatibilizer and antioxidants. The thermogravimetric analysis (TGA) showed that the thermal stability of HDPE decreases slightly with the incorporation of chitosan. However, the composites prepared in the presence of the antioxidants showed a better thermal stability. As for the tensile mechanical properties, there was a slight increase of the elastic modulus and no change of tensile strength, when compared to neat HDPE. On the other hand, there was a considerable reduction of elongation at break. Regarding the impact resistance, a tendency to decrease with the incorporation of chitosan and compatibilizer was observed. The incorporation of the antioxidants did not alter the mechanical behavior of the samples tested. Based on these results it is evident that the rheological characteristics, thermal stability and mechanical resistance of HDPE were very slightly affected by the presence of chitosan, and that the incorporation of the antioxidants resulted in an increase in the thermal stability of HDPE. Therefore, this work shows that HDPE/chitosan composites may be appropriate to prepare eco-friendly films using conventional HDPE industrial equipment and processes.