Structural, morphological, mechanical and thermal properties of PMMA/SiC composites

In this study, silicon carbide (SiC) microfibers were added as reinforcement to improve the thermomechanical properties of poly (methyl methacrylate) polymer, PMMA, since this type of composite has not been explored well enough so far. The aim of this study is to obtain PMMA/SiC composite materials with superior mechanical and thermal qualities out of the starting material, which are customizable for potential applications in flexible electronics as protective/buildable films. Thin PMMA composite films with 0.5 wt.% and 1.0 wt.% SiC microfibers regarding PMMA were made by casting. The Differential Scanning Calorimetry (DSC) analysis verified that the PMMA/SiC composites achieved greater thermal stability than the neat PMMA due to the presence of SiC microfibers. The glass transition temperatures of PMMA/0.5 wt.% SiC and PMMA/1.0 wt.% SiC films were around 2.4°C and 3.5°C higher, respectively, in comparison with the pure PMMA film. The results also showed that the PMMA films with 0.5 wt.% and 1.0 wt.% SiC reinforcement had 17.9% and 55.6% improvement in microhardness, respectively, compared to the neat PMMA film. The Atomic Force Microscopy (AFM) characterization of the PMMA composite films was also carried out. The addition of SiC microfibers to the PMMA polymer matrix also caused an increase in the roughness of the PMMA/SiC films. The average roughness values of the PMMA/SiC films were approximately 3.9 (with 0.5 wt.% SiC) and 13.7 (with 1.0 wt.% SiC) times larger than those obtained for the pure PMMA film. AFM in semi-contact operation mode was used to obtain 3D images of Vickers indents on the surface of PMMA and PMMA/SiC composite films. Both optical and atomic force microscopy approved the presence of pile-up effect after the indentation of PMMA films.