Ismael Romero-Ocana

@uca.es

Facultad de Ciencias , Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
Universidad de Cádiz

Ismael Romero-Ocana


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https://researchid.co/ismael.romero

RESEARCH INTERESTS

Materials Sciences, Biobased composites, catalysis, additive manufacturing.
14

Scopus Publications

Scopus Publications

  • High-Resolution Depth Profiling of Residual Stresses in PVD Coatings on Additively Manufactured Polymers via FIB-DIC and Eigenstrain Theory
    José Daniel Rodríguez-Mariscal, Karuna Srivastava, Ismael Romero-Ocaña, Ramón Escobar-Galindo, Andrea Bernasconi, et al.
    Materials, 2026
    The synergy between additively manufactured (AM) polymers and functional PVD coatings is crucial for advanced applications, yet the reliability of these hybrid systems is dictated by the residual stresses induced during deposition. This work presents the first in-depth, nanoscale profiling of residual stresses in Ti6Al4V and SS316 coatings on 3D-printed Acrylonitrile Styrene Acrylate (ASA) and Silicon (Si) substrates. A cutting-edge methodology combining Focused Ion Beam (FIB) milling with Digital Image Correlation (DIC), rigorously interpreted through the non-integral eigenstrain theory, is employed. Our findings reveal a consistent pattern of compressive stresses near the coating surface but expose a significant tensile stress peak at the coating-substrate interface, a feature not observed on reference silicon substrates. High-resolution electron microscopy and elemental analysis suggest that this stress concentration is associated with the presence of a thin, brittle oxide interlayer formed on the substrate surface. Furthermore, this study quantifies the dominant effect of the low-stiffness polymer substrate, which leads to a strain relief magnitude an order of magnitude higher than in rigid substrates. This work provides critical quantitative data on the failure-driving mechanisms in these emerging material systems and establishes a robust, optimized metrological protocol for their characterization.
  • Potential Use of Residual Powder Generated in Cork Stopper Industry as Valuable Additive to Develop Biomass-Based Composites for Injection Molding
    Ismael Romero-Ocaña, Miriam Herrera, Natalia Fernández-Delgado, Sergio I. Molina
    Journal of Composites Science, 2025
    This study presents the development of a sustainable composite material by incorporating by-products from the cork industry into acrylonitrile butadiene styrene (ABS), with the aim of reducing the environmental impact of plastic composites while maintaining their performance. ABS, a petroleum-based polymer, was used as the matrix, and maleic anhydride (MAH) with dicumyl peroxide (DCP) served as a compatibilizing system to improve interfacial adhesion with cork microparticles. Composites were prepared with 10% w/w cork in various particle sizes and characterized via FTIR, X-ray computed tomography, SEM, mechanical testing, and thermal analysis. The best performing formulation (CPC-125) showed a reduction of only ~16% in tensile modulus and ~7% in tensile strength compared with ABS-g-MAH, with a more pronounced decrease in strain at break (3.23% vs. 17.47%) due to the cork’s inherent rigidity. Thermogravimetric and calorimetric analysis confirmed that thermal stability and processing temperatures remained largely unaffected. These results demonstrate the feasibility of incorporating cork microparticles as a bio-based reinforcing filler in ABS composites, offering a promising strategy to reduce the use of virgin plastics in applications compatible with conventional injection molding.
  • Integrating Cork Biochar as a Green Filler via Photopolymerization
    Ismael Romero-Ocaña, Natalia Fernández-Delgado, Javier Benito, Sergio I. Molina
    Applied Sciences Switzerland, 2025
    This study analyzed the use of cork-derived biochar, obtained through pyrolysis, as a more sustainable additive than traditional carbon materials. In addition, the present study explored its application in a polymer matrix through additive manufacturing via stereolithography. To the best of our knowledge, this approach has not been reported in scientific literature. The cork biochar retained the morphology of the original cork and integrated well into the photocurable polymer, as demonstrated by scanning electron microscopy. This integration can contribute to the formation of internal networks within the material, potentially modifying some of its properties. At specific low percentages, cork biochar enhanced both the electrical conductivity and mechanical properties of photocurable polymers. Notably, the required biochar concentrations were minimal, facilitating its incorporation into the photopolymer matrix. Additionally, the thermal stability of the material slightly improved at certain percentages but remained comparable to that of the original polymer in all cases. These findings highlight the potential of cork biochar as a sustainable additive for advanced polymer composites.
  • Biomass waste from rice and wheat straw for developing composites by stereolithography additive manufacturing
    Ismael Romero-Ocaña, Natalia Fernández Delgado, Sergio I. Molina
    Industrial Crops and Products, 2022
  • Stereolithography of Semiconductor Silver and Acrylic-Based Nanocomposites
    Luisa M. Valencia, Miriam Herrera, María de la Mata, Jesús Hernández-Saz, Ismael Romero-Ocaña, et al.
    Polymers, 2022
    Polymer nanocomposites (PNCs) attract the attention of researchers and industry because of their potential properties in widespread fields. Specifically, electrically conductive and semiconductor PNCs are gaining interest as promising materials for biomedical, optoelectronic and sensing applications, among others. Here, metallic nanoparticles (NPs) are extensively used as nanoadditives to increase the electrical conductivity of mere acrylic resin. As the in situ formation of metallic NPs within the acrylic matrix is hindered by the solubility of the NP precursors, we propose a method to increase the density of Ag NPs by using different intermediate solvents, allowing preparation of Ag/acrylic resin nanocomposites with improved electrical behaviour. We fabricated 3D structures using stereolithography (SLA) by dissolving different quantities of metal precursor (AgClO4) in methanol and in N,N-dimethylformamide (DMF) and adding these solutions to the acrylic resin. The high density of Ag NPs obtained notably increases the electrical conductivity of the nanocomposites, reaching the semiconductor regime. We analysed the effect of the auxiliary solvents during the printing process and the implications on the mechanical properties and the degree of cure of the fabricated nanocomposites. The good quality of the materials prepared by this method turn these nanocomposites into promising candidates for electronic applications.
  • Synthesis and characterization of enhanced conductivity acrylonitrile-butadiene-styrene based composites suitable for fused filament fabrication
    José J. Relinque, Ismael Romero‐Ocaña, Francisco J. Navas‐Martos, Francisco J. Delgado, Manuel Domínguez, et al.
    Polymer Composites, 2022
    This work reports on the design and preparation of composites based on a high impact acrylonitrile‐butadiene‐styrene polymer matrix filled either with aluminium microparticles or graphite nanoplatelets. A surfactant and tin were further added to improve the dispersion and adhesion of the fillers in an attempt to improve the conductivity of the materials. The composites were obtained via twin‐screw extrusion and their performance in fused filament fabrication was successfully tested and compared with other conventional ways of manufacturing plastic parts. Furthermore, the composites were characterized in terms of structure, composition, and thermal/electrical properties. Scanning electron and atomic force microscopies, as well as energy dispersive X‐ray spectrometry, allowed to confirm the presence of added particles and their dispersion within the polymer matrix. Differential scanning calorimetry and conductivity measurements completed the study and revealed enhanced conductivity in the composites as well as a huge decrease in electrical resistivity of the graphite nanoplatelets‐filled nanocomposites, thus resulting in semiconductor materials.
  • Cork photocurable resin composite for stereolithography (SLA): Influence of cork particle size on mechanical and thermal properties
    Ismael Romero-Ocaña, Sergio I. Molina
    Additive Manufacturing, 2022
  • Synthesis and characterisation of acrylic Resin-al powder composites suitable for additive manufacturing
    J. J. Relinque, Ismael Romero-Ocaña, Francisco J. Navas-Martos, F. J. Delgado, M. Domínguez, et al.
    Polymers, 2020
    Stereolithography is an additive manufacturing technology commonly used to build either prototypes or final parts. Nevertheless, the manufacture of structural parts has been ruled out owing to the poor mechanical properties of conventional UV-curable resins. Moreover, the inventory of available commercial resins is still limited and they exhibit low thermal and electrical conductivity values. In this work, some composite materials were designed using Al microparticles dispersed within an SLA commercial resin matrix. These composites overcame the difficulties caused by the light scattering effect during the photopolymerisation process in the SLA technology. Dispersion of the filler was characterised by means of SEM/EDX and AFM. The composites exhibited improved thermal and mechanical behaviour in comparison with the pristine resin. The simplicity of the synthesis method used to prepare the composites provides a convenient starting point to explore new ways of designing composites for SLA with improved mechanical and functional properties.
  • Hot Electron Collection on Brookite Nanorods Lateral Facets for Plasmon-Enhanced Water Oxidation
    Alberto Naldoni, Tiziano Montini, Francesco Malara, Marta M. Mróz, Alessandro Beltram, et al.
    ACS Catalysis, 2017
    Photocatalytic reactions could enhance the share of chemicals produced through renewable sources. The efficiency of photocatalysts drastically depends on light absorption, on the surface energy of the crystals, and on the properties of the nanobuilding blocks assembled in devices. Here, we show that photoelectrochemical water oxidation on brookite TiO2 nanorods is greatly enhanced by engineering the location of Au nanoparticles deposition. Brookite photoanodes show a very low onset potential for water oxidation to H2O2 of −0.2 VRHE due to energetics of exposed crystal facets. By combining electrochemical measurements and ultrafast optical spectroscopy, we link the water oxidation activity with electron–hole recombination phenomena. The preferential Au decoration at the electrode/water interface produces highly enhanced photocurrent, while when Au is distributed along the whole film thickness, the activity is depressed with respect to pure brookite. In the latter case, Au nanoparticles act as recombination...
  • Photocatalytic valorization of ethanol and glycerol over TiO2 polymorphs for sustainable hydrogen production
    Alessandro Beltram, Ismael Romero-Ocaña, Juan Josè Delgado Jaen, Tiziano Montini, Paolo Fornasiero
    Applied Catalysis A General, 2016
  • H2 production by photocatalytic reforming of oxygenated compounds using TiO2-based materials
    Tiziano Montini, Matteo Monai, Alessandro Beltram, Ismael Romero-Ocaña, Paolo Fornasiero
    Materials Science in Semiconductor Processing, 2016
  • Dye-sensitized photocatalytic hydrogen production: Distinct activity in a glucose derivative of a phenothiazine dye
    N. Manfredi, B. Cecconi, V. Calabrese, A. Minotti, F. Peri, et al.
    Chemical Communications, 2016
  • Tuning Thiophene-Based Phenothiazines for Stable Photocatalytic Hydrogen Production
    Bianca Cecconi, Norberto Manfredi, Riccardo Ruffo, Tiziano Montini, Ismael Romero-Ocaña, et al.
    Chemsuschem, 2015
  • Photocatalytic H2 production by ethanol photodehydrogenation: Effect of anatase/brookite nanocomposites composition
    Ismael Romero Ocaña, Alessandro Beltram, Juan Josè Delgado Jaén, Gianpiero Adami, Tiziano Montini, et al.
    Inorganica Chimica Acta, 2015