Influencia del agregado de nanopartículas a films delgados de copolímeros bloques orientados por roll-casting

PASSARETTI G; LOPEZ O; VEGA DA; VILLAR MA

Concepción

Congreso; Congreso internacional de metalurgia y materiales; 2015

Congreso internacional de metalurgia y materiales

Polymer nanocomposites (PNC) are materials of great potential due to its improved final properties. The incorporation of nanoparticles into ordered nanostructures of block copolymers can provide control over the distribution and orientation. Then nanocomposites with enhanced mechanical, optical, electrical and/or barrier?s properties can be obtained.The incorporation of nanoparticles can be achieved by melt-mixing, a solvent-based processing or a combination of both. In this work, a solvent-based processing was used with the subsequent application of an alignment technique: roll-casting. Roll-cast technique allows obtaining macroscopically oriented films while a simple cast technique produces isotropic films.A commercial poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer with 30 wt% styrene (S) was used as a matrix; talc, bentonite, and montmorillonite nanoparticles were used as fillers. Initially, polymer solutions were prepared using cumene as solvent and roll-cast for 5-6 hours. Then, different fillers were added to the polymer solution and processed as before. Resulting films were dried on the roll-caster overnight and once removed from the roll, were vacuum-dried to eliminate the remaining solvent. Finally, films were subjected to an annealing process to improve the orientation. The morphology and final properties of the films were characterized by scanning electron microscopy (SEM), small-angle X-ray scattering (SAXS), tensile strength measurements, water vapor permeation and thermogravimetric analysis. SAXS technique showed hexagonally packed cylinders of PS in the PB matrix and parallel and perpendicular Young?s modulus measurements confirmed the macroscopic orientation of PS cylinders. Water vapor permeability of films can be modified by either macroscopic orientation or by the addition of fillers.