Crude oil, a natural hydrocarbon mixture, is a key energy source and the petrochemical industry’s primary feedstock. Its large-scale processing produces heavy oil fly ash (HOFA), a solid waste that demands effective management. This study explores HOFA’s valorization as a low-cost, carbon-based filler in isotactic polypropylene (iPP) composites. Composites containing 1–20 wt% HOFA were prepared by extrusion and injection molding, then subjected to tensile, impact, and structural analyses (differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS), microscopy). Mechanical testing revealed that even small HOFA additions raised Young’s modulus proportionately to filler content, consistent with typical filled-polymer behavior. Impact strength increased by roughly 25% at both 1 and 20 wt% loadings, while tensile strength and elongation at break remained comparable to neat iPP. DSC and WAXS demonstrated that HOFA acts as a nucleating agent, promoting the β-crystalline phase, known to enhance toughness, without significantly altering the melting or crystallization temperatures.
These findings confirm that HOFA, a waste by-product, can be an effective filler for iPP, improving stiffness and impact resistance without compromising other key properties. Its use offers both economic advantages, through reduced material costs, and environmental benefits by diverting industrial waste from disposal. This approach holds promise for developing sustainable, high-performance polymer composites.

Nowadays, ultra high molecular weight polyethylene (UHMWPE), allows the combination of lightweight, high strength and is praised for the design of severely loaded structures. It has become a good option for lightweight armour solutions. It is therefore important to characterise its mechanical behaviour. Up to now, strain rate effects on mechanical behaviour have been poorly explored. In this work, this issue is tackled by studying the strain rate influence on the in-plane deformation, in shear and tension of the Tensylon^® HSBD30A, a UHMWPE dedicated to ballistic and blast protection. Two laminates of Tensylon^® of respective orientation [0 °/90°]₂₀ and [±45°]₂₀ were subjected to static and split Hopkinson tensile bar (SHTB) tests. A new mounting system was designed, and new specimen shapes were used to match the experimental setup configurations. Digital image correlation (DIC) was used to measure the in-plane strain. A significant strain-rate dependence on the material behaviour.is evidenced. Besides, results exhibit a higher strength for the [0°/90°]₂₀ specimen than for the [±45°]₂₀ one. Despite some limitations, the proposed setup and measurement methods allowed visualisation of strain rate effects on the stress-strain relationship for strain rates ranging from the quasi-static regime to the dynamic one (1500 s^–1).

Thermoplastic (TP) composites, known for their ease of handling, suitability for high production rates, and recyclability, are emerging as a promising alternative to thermoset-based composites. The expected growth in TP-based composites in automotive, sports, and aerospace industries may result in increased post industrial waste. To address this, we repurposed our in-house process scrapped carbon fibre-reinforced polycarbonate tapes into sheet moulding compounds (SMCs) and Hybridised SMCs (Hy-SMCs) using compression moulding. In Hy-SMCs, the top and bottom layers were unidirectional tapes, while the core section had randomly oriented platelets in a 50:50 ratio. Our evaluation included qualitative and thermo-mechanical standard tests. The incorporation of unidirectional tapes in Hy-SMCs significantly improved the tensile and flexural properties of SMCs. Specifically, these enhancements resulted in an impressive 81 to 85% increase in mechanical strength compared to the standard aluminium grade. Additionally, Hy-SMCs exhibited a 120 to 130% increase in tensile and flexural properties compared to SMCs. Fractography revealed a complex relation between fractured surfaces, with multimode failures in both SMCs and Hy-SMCs. Also, the non-destructive evaluation showed platelet reorientation during consolidation and localised voids with increased specimen thickness.

The impact resistance of four polypropylene impact copolymers (ICPs) with multi-phase structures and widely differing characteristics was related to their structure. Blends were prepared from one of them and a high-density polyethylene (HDPE) to improve impact strength further. The structure of the materials was characterized by microscopy and dynamic mechanical thermal analysis. Mechanical properties were determined by tensile and impact testing, while local deformation processes were followed by volume strain measurements. The results obtained in the study proved that the shear-yielding of the matrix contributes the most among local processes to the increase of impact strength, while cavitation has a small effect on this latter property since its energy absorption is negligible. Both increasing elastomer content and decreasing particle size favor shear-yielding, thus improving impact strength. Considering the importance of elastomer content and elastomer particle size, a simple but very good model was created describing the dependence of the impact strength of ICPs on these latter two factors by using linear regression analysis. Although the addition of HDPE increases the fracture resistance of ICPs further, the extent of improvement is moderate, and the approach is economically disadvantageous.

Graphene oxide (GO) nanoplatelets can be used to reinforce neat resin or the matrix phase of fiber composites for improved mechanical properties. Although the oxygen content levels in GO and reduced graphene oxide (rGO) strongly influence the interface with the polymer, experimental-based optimization of the oxygen content for enhanced composite properties is difficult and time-consuming. Fortunately, molecular dynamics (MD) simulation can be used to efficiently predict the interfacial properties of composite on the molecular level and provide physical insight into the effect of the oxygen content of rGO. In this study, MD is used to predict the elastic properties of rGO/epoxy interfaces and the corresponding interfacial shear strength (IFSS) for different oxygen content levels. The results indicate that increasing levels of oxygen in rGO results in interfaces with a reduced in-plane elastic modulus but a substantially higher IFSS. These results are important for the design of rGO/epoxy composites for specific engineering applications.