The present study aims to evaluate thin plate-injected polypropylene (PP) composites containing short aramid fibers (AF) and graphene nanoplatelets (GNPs). The aramid fibers were manually cut to a length of 10 mm and added to the polypropylene matrix at a concentration of 10 wt.%. Additionally, GNPs were incorporated at concentrations of 0.1, 0.25, and 0.5 wt.%. Maleic anhydride grafted polypropylene (MAPP) was used at a concentration of 2 wt.% to improve the adhesion and compatibility between the polymer matrix and the fillers. Thermal analyses, tensile and flexural tests, and dynamic mechanical thermal analysis were performed, followed by statistical analysis using ANOVA and Tukey’s test. The composites demonstrated significant improvements in storage and loss moduli compared to neat polypropylene. With the addition of AF and GNPs, tensile strength increased to 46.8 MPa, which represents a 265% enhancement compared to PP. Similarly, flexural strength reached 62.4 MPa, significantly higher than the 36.73 MPa for PP, particularly for the composite containing AF and 0.25 wt.% GNPs. The results presented in this study highlight the synergistic effect of aramid fibers and GNPs on PP. These improvements make the proposed composites highly promising for a range of applications, including ballistic interlayered aramid/thin-plate laminates.@en

Different amounts of graphene quantum dots (CQDs) (0, 1, 2.5, and 5 wt%) were incorporated into an epoxy matrix. The thermal conductivity, density, morphology, and dynamic mechanical thermal (DMTA) properties were reused from the study of Seibert et al.. The Pearson plot showed a high correlation between mass loading, thermal conductivity, and thermal diffusivity. A poorer correlation with density and heat capacity was observed. At lower CQD concentrations (0.1 wt%), the fracture surface showed to be more heterogeneous, while at higher amounts (2.5 and 5 wt%), a more homogeneous surface was observed. The storage modulus values did not change with the CQD amount. But the extension of the glassy plateau increased with higher CQD contents, with an increase of ~40 °C for the 5 wt% compared to the 2.5 wt% and almost twice compared to the neat epoxy. This result is attributed to the intrinsic characteristics of the filler. Additionally, lower energy dissipation and a higher glass transition temperature were observed with the CQD amount. The novelty and importance are related to the fact that for more rigid matrices (corroborated with the literature), the mechanical properties did not change, because the polymer bridging mechanism was not present, in spite of the excellent CQD dispersion as well as the filler amount. On the other hand, thermal conductivity is directly related to particle size and dispersion.@en