A novel class of graphene-based materials incorporated into natural lignocellulosic fiber (NLF) polymer composites is surging since 2011. The present overview is the first attempt to compile achievements regarding this novel class of composites both in terms of technical and scientific researches as well as development of innovative products. A brief description of the graphene nature and its recent isolation from graphite is initially presented together with the processing of its main derivatives. In particular, graphene-based materials, such as nanographene (NG), exfoliated graphene/graphite nanoplatelet (GNP), graphene oxide (GO) and reduced graphene oxide (rGO), as well as other carbon-based nanomaterials, such as carbon nanotube (CNT), are effectively being incorporated into NLF composites. Their disclosed superior mechanical, thermal, electrical, and ballistic properties are discussed in specific publications. Interfacial shear strength of 575 MPa and tensile strength of 379 MPa were attained in 1 wt % GO-jute fiber and 0.75 wt % jute fiber, respectively, epoxy composites. Moreover, a Young’s modulus of 44.4 GPa was reported for 0.75 wt % GO-jute fiber composite. An important point of interest concerning this incorporation is the fact that the amphiphilic character of graphene allows a better way to enhance the interfacial adhesion between hydrophilic NLF and hydrophobic polymer matrix. As indicated in this overview, two basic incorporation strategies have so far been adopted. In the first, NG, GNP, GO, rGO and CNT are used as hybrid filler together with NLF to reinforce polymer composites. The second one starts with GO or rGO as a coating to functionalize molecular bonding with NLF, which is then added into a polymeric matrix. Both strategies are contributing to develop innovative products for energy storage, drug release, biosensor, functional electronic clothes, medical implants, and armor for ballistic protection. As such, this first overview intends to provide a critical assessment of a surging class of composite materials and unveil successful development associated with graphene incorporated NLF polymer composites.

Natural lignocellulosic fibers (NLFs) have been used as a reinforcement for polymer matrix composites in the past couple of decades. Their biodegradability, renewability, and abundance make them appealing for sustainable materials. However, synthetic fibers surpass NLFs in mechanical and thermal properties. Combining these fibers as a hybrid reinforcement in polymeric materials shows promise for multifunctional materials and structures. Functionalizing these composites with graphene-based materials could lead to superior properties. This research optimized the tensile and impact resistance of a jute/aramid/HDPE hybrid nanocomposite by the addition of graphene nanoplatelets (GNP). The hybrid structure with 10 jute/10 aramid layers and 0.10 wt.% GNP exhibited a 2433% increase in mechanical toughness, a 591% increase in tensile strength, and a 462% reduction in ductility compared to neat jute/HDPE composites. A SEM analysis revealed the influence of GNP nano-functionalization on the failure mechanisms of these hybrid nanocomposites.

Graphene nanoplatelets (GNPs) are efficient nanofillers for improving the mechanical and thermal properties of epoxy resins due to their high stiffness, aspect ratio, and interfacial reinforcement ability. This study employs a three-factor, three-level Box–Behnken Design (BBD) to investigate the combined effect of GNP content (0.5–3.5 wt.%), hardener concentration (9–17 phr), and post-curing temperature (30–120 °C) on DGEBA/TETA epoxy nanocomposites. Mechanical, thermal, dynamic mechanical, and morphological characterizations (flexural testing, DMA, TGA, DSC, FTIR, SEM, TEM, and AFM) established structure–property correlations. The optimized formulation (2.0 wt.% GNP, 9 phr hardener, and 120 °C post-curing) exhibited superior reinforcement, with flexural strength of 322.0 ± 12.8 MPa, flexural modulus of 9.7 ± 0.5 GPa, and strain at break of 4.4 ± 0.2%, corresponding to increases of 197%, 155%, and 91% compared with neat epoxy. DMA confirmed a rise in storage modulus from 2.9 to 7.5 GPa and a Tg of 143 °C, while TGA showed a 15 °C improvement in thermal stability. Statistical analysis identified post-curing temperature as the dominant factor governing Tg, stiffness, and thermal stability, with synergistic contributions from GNP content and hardener concentration to the overall network performance. These results surpass those of GO- and CNT-based systems, demonstrating the superior efficiency of GNPs under optimized conditions. The proposed approach provides a robust pathway for developing epoxy nanocomposites with low filler content and enhanced multifunctional performance.

The mechanical and ballistic performance of epoxy matrix composites reinforced with 10, 20, and 30 vol.% of babassu fibers was investigated for the first time. The tests included tension, impact, and ballistic testing with 0.22 caliber ammunition. The results showed an improvement in tensile strength, elastic modulus, and elongation with the addition of babassu fiber, and the 30 vol.% composite stood out. Scanning electron microscopy analysis revealed the fracture modes of the composites, highlighting brittle fractures in the epoxy matrix, as well as other mechanisms such as fiber breakage and delamination in the fiber composites. Izod impact tests also showed improvement with increasing babassu fiber content. In ballistic tests, there was an increase in absorbed energy. All composites surpassed plain epoxy by over 3.5 times in ballistic energy absorption, underscoring the potential of babassu fiber in engineering and defense applications.

Fracture resistance of polyamide 12 was measured with tensile tests on notched specimens with different notch tip radii. The specimens were processed by additive manufacturing techniques, and the tests were carried out in two different orientations to evaluate the potential anisotropy of the material. Finite element analysis was performed to know the stress state of the whole specimen. Then, the failure of the specimens was described using the theory of critical distances. The influence of possible manufacturing defects in the material was incorporated using a probabilistic approach, associated with a Weibull distribution. A fractographic analysis of the post-mortem specimens allowed to identify those mechanisms responsible for the material failure in each orientation.

Elasticity and Strength of Materials is an elementary discipline across many engineering degrees. Students perceive it as very difficult and abstract and students’ active participation in the learning process is needed, due to its complexity and importance during the whole degree years. Hence, the main difficulty in teaching them is maintaining students' motivation and keeping their participation in the learning process. This is the reason to use new tools, such as problem-based learning (PBL) and flipped classroom, to help students understand and study the subject. In this work, we present the application of a problem-based learning to the lab in the Mechanical engineering degree, in of one the most time-consuming and difficult subjects of its program. Moreover, to enhance students’ enthusiasm and motivation, these sessions included an innovative manufacturing technology, 3D printing, and digital image correlation (DIC). Before each practical session, the students are encouraged to watch an online video with the fundamental aspects. In order to assess the success of this laboratory course, after finishing the lab sessions, the students answered a non-formal quantitative survey. The results showed that the proposed project-based learning had the ability to help integrating the knowledge and improve the skills included in the main competences. Although these results are encouraging, there are still parts of the lab activity that should be improve in order to make the activity less time consuming and the most difficult part being easier for the students.