Caracterización térmica y mecánica de materiales compuestos de matriz epóxica reforzados con partículas cerámicas termomióticas

Abstract

Yttrium tungstate (Y2W3O12) is a ceramic material that exhibits a high negative thermal expansion (NTE) and, therefore, is a potential reinforcement for reducing the coefficient of thermal expansion (CTE) of polymeric matrices. In this work, to corroborate this hypothesis, epoxy-based composites filled with Y2W3O12 particles of two sizes (0,3 and 0,8 µm) were prepared. Nevertheless, one of the main problems for the application of Y2W3O12 as a reinforcement is its high higroscopicity, which affects its NTE. Thus, prior to the preparation of composites, a procedure for drying Y2W3O12 particles was developed in order to eliminate structural water. Subsequently, the as-prepared composites were characterized through thermomechanical analysis (TMA) to determine the optimum concentration of Y2W3O12, being 5.0 wt. %, the filler content that resulted in the highest reduction of the CET of the matrix (~5.1 %). By differential scanning calorimetry (DSC) and TMA it was verified that the filler content did not affect the glass transition temperature of the composites. Moreover, the elastic modulus of the as-prepared composite with the optimum concentration of Y2W3O12 (5.0 wt. %) increased by 7.8 %, as confirmed through flexural test. However, the flexure strength decreased by 8.0 %. Finally, the experimental values of CTE of as-prepared composites were compared with results obtained through micromechanical models, verifying that it is not possible to predict this thermal property through a single theoretical model.