The Role of Organo-Clay Characteristics on the Final Properties of Polycaprolactone Clay Nanocomposites

JOSÉ KENNY; ANALÍA VÁZQUEZ; VERA ALVAREZ; LEANDRO LUDUEÑA

Congreso; . Hybrid Materials 2011; 2011

Because of waste accumulation at the end of the life cycle of traditional polymer products, the development of environmental friendly, degradable, polymeric materials has attracted extensive interest. Polycaprolactone (PCL) is a chemically synthesized polymer based on caprolactone units. It does not occur in nature but it is fully biodegradable. In order to obtain a competitive product, the PCL performance can be greatly enhanced with the addition of nanometer-size inorganic fillers (montmorillonite). The use of a non-polar polymer matrix force to take advance of the cation exchange capacity of the natural montmotillonite to change the sodic cations located into the galleries by large hydrophobic organo-modifiers. In this work, the effect of addition of different organo-modified clays on the behavior of PCL based nanocomposites prepared by melt intercalation was studied. This study contemplates morphological and thermal aspects, mechanical and barrier properties and also biodegradability. METHODS The clay dispersion degree inside the nanocomposites was analyzed by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The melt rheology was used as a method to compare the dispersion degree of the clay by means of the shear thinning exponent, nRe. The tensile properties were determined in a universal testing machine. Special effort was made to analyze the thermal stability of the clay modifiers at testing conditions in accordance with the extrusion processing parameters. RESULTS AND DISCUSION The obtained results suggest that the optimal chemical compatibility between the polymer and the reinforcement could not lead to a nanocomposite with optimized final properties if the mechanical and thermal degradation of the clay organo-modifier is not taken into account. Fig. 1 shows that thermal degradation is happening at processing temperatures of traditional polymers. The thermal degradation of the modifiers may lead to differences in the final reinforcement content inside the nanocomposite as is shown in Fig. 2.