Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE In this study, a comparison was made between micro- and nano-sized SiO2 incorporated into the PP/PP-g-MA matrix blend, and their effects on the mechanical, thermal, morphological, and hydrophobic properties of the composites were analyzed. The following figure presents a schematic along with a comparison of the composites characteristics and properties based on analysis results obtained.

ABSTRACT
This study investigates the effect of the particle size of silicon dioxide (SiO2), specifically micro-size (m-SiO2) and nano-size (n-SiO2), on the properties of polypropylene (PP)/polypropylene-grafted maleic anhydride (PP-g-MA) composites. The composites were prepared by melt mixing in a twin-screw extruder, followed by compression molding. Based on mechanical and thermal characterization, the inclusion of m-SiO2 enhanced composite rigidity but reduced ductility and flexibility, whereas n-SiO2 exhibited the highest maximum decomposition temperature (Tpeak), indicating high thermal stability. FTIR analysis confirmed the formation of hydrogen-bonding interactions between SiO2 and PP-g-MA, thereby enhancing filler-matrix adhesion. Furthermore, XRD results demonstrated that particle size plays a crucial role in governing the interfacial behavior of the composites. Morphological and surface properties indicate that the incorporation of n-SiO2 into the matrix PP/PP-g-MA results in a more homogeneous dispersion with lower levels of agglomeration and pull-out defects compared to m-SiO2, leading to a denser and more cohesive composite structure. This improved morphology promotes stronger interfacial interactions and significantly enhances the hydrophobic surface properties of the composites, as evidenced by a 9.91% increase in the water contact angle for the n-SiO2 based composite compared with the m-SiO2 filled composite.