Effect of functionalized patagonian bentonite on polycapro-lactone composites characteristics

G. PUNTE; A. E. BIANCHI; I.L. TORRIANI; P. EISENBERG; A. F. BOTANA; M. MOLLO; R. M. TORRES SÁNCHEZ

Santa fe

Congreso; VIII Reunión Anual de la Asociación Argentina de Cristalografía; 2012

Asociación Argentina de Cristalografía

Enhancement of environmentally caring polymeric materials performance is a field of great activity and ecological interest. Polymers blended with natural minerals in the form of nanoparticles lead to composites with highly improved stiffness, thermal stability, decreased flammability and gas-barrier properties at low loading (l.t. 5 vol per cent). Natural clay minerals are a good choice to this end due to their availability, low cost and the possibility of changing their physicochemical properties by different methods. The first step in the development of nanocomposites polymer-silicate is the intercalation of cationic surfactants in the selected clay. We have synthesized organoclays by intercalation of an Argentinean bentonite with hexadecyltrimethylammonium (HDTMA) and octadecyltrimethyl-ammonium (ODTMA). The employed bentonite is predominately sodium montmorillonite (MMT), structural formula: [(Si3.89 Al0.11) (Al1.43 Fe0.26 Mg0.30)] M+0.41, cation exchange capacity (CEC): 174 meq/100g, isoelectric point    (IPpH): 2.7), external surface area 34.0 m2/g and total specific surface area 621 m2/g [1]. The organoclays (OMMTs) were produced by addition of 1 and 2 CEC of ODTMA and HDTMA to raw MMT diluted in deionized water. Both loading of HDTMA and 1 CEC of ODTMA samples present a distribution of interlayer spacing values covering a wide range. While 2 CEC ODTMA sample shows several but well defined interlayer spacing values denoting a structural regularity that is reflected in its flat plate particles, as seen from TEM micrographies, at all loadings both surfactants not only occupy clay interlayer spaces but also particle surfaces [2]. In this work polymer composite films, based on a semicrystalline biodegradable thermoplastic polyester, polycaprolactone (PCL), and the prepared OMMTs and their microstruture are compared with that of a PCL film obtained from PCL and a commercial montmorillonite (Cloisite 30B) [3]. All composite films were prepared by melt intercalation technique at 100 C and characterized by X Ray Diffraction and Small Angle X Ray Dispersion. [1] Magnoli. A. P. et al. (2008) Appl. Clay Sci. 40, 63-71.[2] Bianchi et al. ODTMA and HDTMA organomontymorillonites characterization: new insight by WAXS, SAXS and surface charge. Sent for publication to Appl. Clay Sci. [3] Bianchi et al. Effect of montmorillonite organic modification on  polycaprolactone composites properties. To be published in Actas de la VII Reunión anual de la AACr.