16 research outputs found
Development, dielectric response, and functionality of ZnTiO<sub>3</sub>/BaTiO<sub>3</sub>/epoxy resin hybrid nanocomposites
No full textIn the present work, hybrid nanocomposites of an epoxy resin reinforced with ZnTiO3 and BaTiO3 nanoparticles, at various filler contents, were fabricated and studied. The successful integration of ceramic nanofillers and the fine distribution of nanoparticles were confirmed via X-ray Diffraction patterns and Scanning Electron Microscopy images, respectively. Dielectric properties and related relaxation phenomena were investigated via Broadband Dielectric Spectroscopy in a wide range of frequencies and temperatures. Data analysis showed that dielectric permittivity increases with filler content, although optimum performance does not correspond to the maximum ZnTiO3 content. Four relaxation processes were observed and attributed to interfacial polarization (IP) (at low frequencies and high temperatures), glass-to-rubber transition (α-relaxation) of the epoxy matrix (at intermediate frequencies and temperatures), and local rearrangements of polar side groups of the macromolecules (β-relaxation) and small flexible groups of the main polymer chain (γ-relaxation) occurring at low temperatures and high frequencies. The ability of hybrid nanocomposites to store and retrieve energy was studied under dc conditions by employing a charging/discharging sequence. The stored and retrieved energy increases with filler content and charging voltage. The optimum ability of energy recovering, shown by the epoxy/7 phr ZnTiO3/7 phr BaTiO3 nanocomposite, ranges between 30 and 50 times more than the matrix, depending on the time instant. The employed nanoparticles induce piezoelectric properties in the nanocomposites, as found by the increase in the piezoelectric coefficient with filler content
End-Of-Use Fly Ash as an Effective Reinforcing Filler in Green Polymer Composites
No full textThe aim of this study is to use fly ash powder in an environmentally friendly matrix, in a novel way, addressing environmental and disposal problems. Fly ash/epoxy composites were prepared and studied varying the filler content. An investigation of structural and morphological characteristics was conducted using of X-ray diffraction patterns and scanning electron microscopy images, which revealed the successful fabrication of composites. Thermomechanical properties were studied via dynamic mechanical analysis and static mechanical tests. The composites exhibited an improved mechanical response. Broadband dielectric spectroscopy was used to investigate the dielectric response of the composite systems over the frequency range from 10−1 to 107 Hz and the temperature range from 30 to 160 °C. The analysis revealed the presence of three relaxation processes in the spectra of the tested systems. Interfacial polarization, the glass-to-rubber transition of the polymer matrix, and the rearrangement of polar side groups along the polymer chain are the processes that occur under a descending relaxation time. It was found that dielectric permittivity increases with filler content. Finally, the influence of filler content and the applied voltage under dc conditions was analyzed to determine the ability of the composites to store and retrieve electric energy. Fly ash improved the efficiency of the storing/retrieving energy of the composites
Hybrid nanodielectrics of polymer matrix/functional composites: development, characterization and functionality
No full textIn this study, series of polymer matrix composite materials were developed and experimentally studied, varying the reinforcing phase content. The employed matrix was a high tech epoxy resin, while reinforcing phase was micro- and/or nano-barium titanate particles, as well as exfoliated graphite nanoplatelets. The choice of the materials was targeting to take advantage in a common composite system of the thermo-mechanical stability of the matrix, the high dielectric permittivity and the ferroelectric behaviour of barium titanate and the enhanced mechanical properties in tandem with the high conductivity of the exfoliated graphite nanoplatelets. The following composite materials systems were fabricated and studied, for various filler contents:(a)barium titante micro-particles/epoxy resin composite system,(b)barium titante nano-particles/epoxy resin composite system,(c)exfoliated graphite nanoplatelets/epoxy resin composite system,(d)barium titante micro-particles/barium titante nano-particles /epoxy resin hybrid composite system,(e)exfoliated graphite nanoplatelets /barium titante nano-partcles /epoxy resin hybrid composite system.The fabrication of the composites was followed by a multiple characterization of the produced specimens. For reference reasons pure resin was also prepared and studied. Systems’ morphology was investigated by means of scanning electronic microscopy and x-ray diffraction scattering. It was ascertained the existence of fine nanodispersions, as well as of small clusters, within the composites. XRD spectra verified the presence of filler in each category of composite systems. Thermal characterization was conducted via differential scanning calorimetry aiming to determine the glass to rubber transition temperature of all studied systems. Mechanical behaviour was investigated under static and dynamic conditions. Static behaviour was determined via three point bending tests at ambient temperature. It was found that modulus of elasticity increases with filler content in all composite systems categories. On the other hand, mechanical strength decreases with filler content. Dynamic response was studied by means of dynamic mechanical thermal analysis in a wide temperature range. Reinforced systems exhibit higher values of storage modulus, while the loss tangent peaks allow the determination of the glass transition temperature Tg. Tg slightly varies with reinforcing phase content, to higher or lower values depending on the type and the amount of filler concentration. These variations express the interactions between the phases of the composites and possibly the uncompleted wetting of the inclusions in some cases. The electrical response of the composite systems was examined by means of broadband dielectric spectroscopy in a wide frequency and temperature range. The analysis of the experimental data was carried out via the dielectric permittivity, electric modulus, and ac conductivity formalisms. The usage of all three formalisms provides the opportunity to extract more information concerning the physical mechanisms occurring within the composites. It was found that two dielectric processes are related to the polymer matrix. These are attributed to the glass to rubber transition of epoxy resin (α-relaxation) and to the re-arrangement of polar side groups of the main polymer chain (β-relaxation). The presence of inclusions within the matrix introduces electrical heterogeneity resulting in the occurrence of interfacial polarization. Unbounded charges accumulate at the interface of the phases, forming large dipoles, which exhibit inertia in orienting themselves parallel to the applied field. Interfacial polarization is the slowest process in the systems and thus it is observed at low frequencies and high temperatures. The real part of dielectric permittivity, as well as, the conductivity increase with reinforcing phase content, especially in the case of the systems with graphite nanoplatelets. The energy storage efficiency was investigated via the density of energy, at constant electric field. It was found that the energy storage capability increases with filler content. Optimum behaviour is displayed by the system with maximum content in graphite nanoplatelets.The dynamics of the relaxations was studied via Arrhenius graphs, from which the values of activation energy were calculated. Interfacial polarization and α-relaxation appear in adjacent temperature ranges, leading in a superposition of both processes. From the calculated values of activation energy it is concluded that in the pure resin specimen the dominating contribution is related to the α-relaxation, while in the composite systems the contribution of interfacial polarization seems to prevail.Barium titanate particles undergo a structural transition from the polar tetragonal structure (ferroelectric phase) to the non-polar cubic structure (paraelectric phase) at a critical temperature closed to 130oC. This transition was proved via XRD spectra and is more intense in the case of barium titanate microparticles.Systems’ functional behaviour is related to the thermally stimulated structural transition from the ferroelectric to the paraelectric phase of barium titanate inclusions, to the change of sign of the temperature coefficient of conductivity, and their ability for energy storage.The coexistence at adjacent temperatures ranges of α-relaxation and interfacial polarization, as well as the critical transition temperature of ferroelectric inclusions, hampers the discrimination of the effects. By introducing the dielectric reinforcing function the discrimination of the processes became possible. Furthermore, the dielectric reinforcing function provides the possibility to examine the functional behaviour and the energy storage efficiency of the systems, neglecting the materials’ geometrical characteristics influence. Finally, experimental results and analysis are compared and discussed.Στην παρούσα εργασία αναπτύχθηκαν και μελετήθηκαν πειραματικά σειρές σύνθετων υλικών πολυμερικής μήτρας, με παράμετρο τον τύπο και την περιεκτικότητα σε ενισχυτική φάση. Ως μήτρα χρησιμοποιήθηκε εποξειδική ρητίνη υψηλών προδιαγραφών. Ως ενισχυτική φάση χρησιμοποιηθήκαν μικροσωματίδια, νανοσωματίδια τιτανικού βαρίου και αποφλοιωμένα γραφιτικά νανοεπίπεδα (exfoliated graphite nanoplatelets). Η επιλογή των υλικών είχε ως στόχο να εκμεταλλευτούν σε κοινό σύνθετο σύστημα οι «θετικές» ιδιότητες των συστατικών του, όπως η θερμο-μηχανική σταθερότητα της μήτρας, η υψηλή διαπερατότητα και η σιδηροηλεκτρική συμπεριφορά του τιτανικού βαρίου και οι καλές μηχανικές ιδιότητες μαζί με την υψηλή ειδική αγωγιμότητα των αποφλοιωμένων γραφιτικών νανοεπιπέδων.Παρασκευάστηκαν και μελετήθηκαν τα παρακάτω συστήματα σύνθετων υλικών, για διάφορες περιεκτικότητες σε ενισχυτική φάση: (α) σύστημα μικροσωματιδίων τιτανικού βαρίου/εποξειδικής ρητίνης,(β) σύστημα νανοσωματιδίων τιτανικού βαρίου/εποξειδικής ρητίνης,(γ) σύστημα αποφλοιωμένων γραφιτικών νανοεπιπέδων/εποξειδικής ρητίνης, (δ) υβριδικό σύστημα μικροσωματιδίων τιτανικού βαρίου/νανοσωματιδίων τιτανικού βαρίου/εποξειδικής ρητίνης,(ε) υβριδικό σύστημα αποφλοιωμένων γραφιτικών νανοεπιπέδων/ νανοσωματιδίων τιτανικού βαρίου/εποξειδικής ρητίνης. Την παρασκευή των δοκιμίων ακολούθησε πολύπλευρος χαρακτηρισμός τους. Για λόγους αναφοράς παρασκευάστηκε και μελετήθηκε και δοκίμιο μη ενισχυμένης ρητίνης. Η μορφολογία τους διερευνήθηκε με την τεχνική της ηλεκτρονικής μικροσκοπίας σάρωσης (scanning electron microscopy) και την τεχνική σκέδασης ακτίνων-Χ (x-ray diffraction scattering). Διαπιστώθηκε η επιτυχής διασπορά των νανο-εγκλεισμάτων αλλά και η ύπαρξη μικρών συσσωματωμάτων. Τα φάσματα σκέδασης ακτίνων-Χ πιστοποίησαν την παρουσία των πληρωτικών μέσων που χρησιμοποιήθηκαν σε κάθε κατηγορία σύνθετου συστήματος. Ακολούθησε θερμικός χαρακτηρισμός των σύνθετων υλικών, με στόχο τον προσδιορισμό της θερμοκρασίας υαλώδους μετάπτωσής τους. Η μελέτη της μηχανικής συμπεριφοράς των συνθέτων έγινε υπό στατικές και δυναμικές συνθήκες. Η στατική συμπεριφορά εξετάστηκε με την τεχνική κάμψης τριών σημείων σε θερμοκρασία περιβάλλοντος. Διαπιστώθηκε αύξηση του μέτρου ελαστικότητας με την περιεκτικότητα σε ενισχυτική φάση, σε όλες τις κατηγορίες σύνθετων συστημάτων. Παράλληλα, διαπιστώθηκε μείωση της μηχανικής αντοχής με τη συγκέντρωση πληρωτικού μέσου σε όλες τις κατηγορίες σύνθετων υλικών που μελετήθηκαν. Η δυναμική μηχανική απόκριση μελετήθηκε με την τεχνική της δυναμικής θερμικής ανάλυσης (dynamic mechanical thermal analysis) σε ευρύ φάσμα θερμοκρασιών. Τα ενισχυμένα συστήματα παρουσιάζουν αυξημένες τιμές του μέτρου αποθήκευσης, ενώ οι κορυφές της εφαπτομένης απωλειών επιτρέπουν τον προσδιορισμό της θερμοκρασίας υαλώδους μετάπτωσης (Tg). Η Tg φαίνεται να διαφοροποιείται ελαφρά με την περιεκτικότητα σε ενισχυτική φάση, άλλοτε προς μεγαλύτερες και άλλοτε προς μικρότερες τιμές. Οι διαφοροποιήσεις αυτές εκφράζουν τις αλληλεπιδράσεις μεταξύ των φάσεων και ίσως την πλήρη ή μη διαβροχή των εγκλεισμάτων από τη μήτρα. Η ηλεκτρική απόκριση των σύνθετων συστημάτων εξετάστηκε με τη μέθοδο της διηλεκτρικής φασματοσκοπίας ευρέως φάσματος, σε μεγάλο εύρος συχνοτήτων και θερμοκρασιών. Η ανάλυση των πειραματικών δεδομένων έγινε μέσω των φορμαλισμών της ηλεκτρικής διαπερατότητας, του ηλεκτρικού μέτρου και της ειδικής αγωγιμότητας εναλλασσομένου. Η χρήση και των τριών φορμαλισμών προσφέρει τη δυνατότητα εξαγωγής περισσότερων πληροφοριών για τις φυσικές διεργασίες που λαμβάνουν χώρα στο εσωτερικό των συνθέτων. Διαπιστώθηκε η παρουσία δύο διηλεκτρικών χαλαρώσεων που σχετίζονται με την πολυμερική μήτρα. Αυτές αποδίδονται, στη μετάπτωση από την υαλώδη στην ελαστομερική φάση της εποξειδικής ρητίνης (α-χαλάρωση) και στην επαναδιευθέτηση πλευρικών πολικών ομάδων (β-χαλάρωση). Η παρουσία των εγκλεισμάτων στο εσωτερικό της μήτρας εισάγει ηλεκτρική ετερογένεια με αποτέλεσμα την εμφάνιση του φαινομένου διεπιφανειακής πόλωσης (interfacial polarization). Μη δέσμια φορτία συσσωρεύονται στη διεπιφάνεια των φάσεων, όπου σχηματίζουν μεγάλα δίπολα που παρουσιάζουν αδράνεια ως προς τον προσανατολισμό τους, παράλληλα του εφαρμοζόμενου πεδίου. Η διεπιφανειακή πόλωση είναι η πλέον αργή διεργασία και παρατηρείται σε χαμηλές συχνότητες και υψηλές θερμοκρασίες. Το πραγματικό μέρος της ηλεκτρικής διαπερατότητας, όπως και η ειδική αγωγιμότητα παρουσίασαν αύξηση με την περιεκτικότητα σε ενισχυτική φάση, ιδιαίτερα στην περίπτωση των συστημάτων με γραφιτικά νανοεπίπεδα. Η δυνατότητα αποθήκευσης ενέργειας στα συστήματα διερευνήθηκε με χρήση της πυκνότητας ενέργειας υπό σταθερό ηλεκτρικό πεδίο. Διαπιστώθηκε αύξηση της αποθηκευόμενης ενέργειας με αύξηση της περιεκτικότητας σε ενισχυτική φάση. Τη βέλτιστη συμπεριφορά επέδειξε το σύστημα με τη μέγιστη περιεκτικότητα σε γραφιτικά νανοεπίπεδα.Η δυναμική των χαλαρώσεων μελετήθηκε μέσω διαγραμμάτων Arrhenius, από τα οποία προέκυψαν και οι τιμές της ενέργειας ενεργοποίησης. Η θερμοκρασιακή γειτνίαση των διεργασιών της α-χαλάρωσης και της διεπιφανειακής πόλωσης οδήγησε σε αλληλοεπικάλυψη των διεργασιών. Από τις ενέργειες ενεργοποίησης που υπολογίστηκαν φαίνεται πως στο δοκίμια της μη ενισχυμένης ρητίνης επικρατεί η συνεισφορά της α-χαλάρωσης, ενώ στα σύνθετα συστήματα επικρατεί η συνεισφορά της διεπιφανειακής πόλωσης. Τα σωματίδια του τιτανικού βαρίου υφίστανται δομικό μετασχηματισμό από την πολική τετραγωνική δομή (σιδηροηλεκτρική φάση) στην μη-πολική κυβική δομή (παραηλεκτρική φάση) σε μία κρίσιμη θερμοκρασία, πλησίον των 130οC. Η μετάβαση αποδείχθηκε μέσω των φασμάτων ακτίνων-Χ και είναι περισσότερο έντονη στην περίπτωση των μικροσωματιδίων.Η λειτουργική συμπεριφορά των συστημάτων σχετίζεται με τη θερμικά διεγειρόμενη δομική μετάβαση από τη σιδηροηλεκτρική στην παραηλεκτρική φάση των εγκλεισμάτων τιτανικού βαρίου, τη μεταβολή του προσήμου του θερμοκρασιακού συντελεστή ειδικής αγωγιμότητας και τη δυνατότητα αποθήκευσης ενέργειας.Η συνύπαρξη σε κοντινές θερμοκρασίες των διεργασιών α-χαλάρωσης και διεπιφανειακής πόλωσης μαζί με την κρίσιμη θερμοκρασία μετάβασης των σιδηροηλεκτρικών εγκλεισμάτων, δυσχεραίνει πολύ την διάκρισή τους. Με την εισαγωγή της διηλεκτρικής συνάρτησης ενίσχυσης (dielectric reinforcing function) έγινε δυνατός ο διαχωρισμός των φαινομένων. Επιπλέον, η συνάρτηση διηλεκτρικής ενίσχυσης προσφέρει τη δυνατότητα εξέτασης της λειτουργικής συμπεριφοράς και της δυνατότητας αποθήκευσης ενέργειας, ανεξάρτητα των γεωμετρικών διαστάσεων του υλικού. Τέλος, το σύνολο των αποτελεσμάτων έγινε αντικείμενο συγκρίσεων και συζήτησης
Dielectric Properties and Energy Storage of Hybrid/Boron Nitride/Titanium Carbide/Epoxy Nanocomposites
No full textIn this study, hybrid boron nitride (BN)/titanium carbide (TiC)/epoxy resin composite nanodielectrics were manufactured and characterized. Their morphological and structural characterization was conducted via scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns, whereas the dielectric behavior was studied by means of broadband dielectric spectroscopy (BDS). Dielectric measurements were carried out from 30 to 160 °C and from 10−1 to 106 Hz, respectively. The dielectric results revealed the existence of three relaxation mechanisms, which from high to low frequencies, at constant temperature, refer to re-arrangement of polar-side groups (β-relaxation) of the macromolecular chains, transition from glassy to rubbery state of the amorphous polymer matrix (α-relaxation) and interfacial polarization (IP) between the polymer matrix and the nanofillers. It was found that, in general, nanodielectrics exhibited enhanced dielectric properties mainly due to the high dielectric permittivity of TiC and the fine dispersion of the fillers, confirmed also by the SEM images. Dynamic analysis conducted for the α-relaxation showed a Vogel–Fulcher–Tammann dependence on temperature. The ability of energy storing of the nanocomposites was examined via their energy density. Optimum performance is exhibited by the 5 phr TiC/1 phr BN/epoxy nanocomposite, reaching an energy storing ability nine times greater than the unfilled matrix
Development and Characterization of 3D Printed Multifunctional Bioscaffolds Based on PLA/PCL/HAp/BaTiO3 Composites
No full textBone substitute materials are placed in bone defects and play an important role in bone regeneration and fracture healing. The main objective of the present research is fabrication through the technique of 3D printing and the characterization of innovative composite bone scaffolds composed of polylactic acid (PLA), poly (ε-caprolactone) (PCL) while hydroxyapatite (HAp), and/or barium titanate (BaTiO3—BT) used as fillers. Composite filaments were prepared using a single screw melt extruder, and finally, 3D composite scaffolds were fabricated using the fused deposition modeling (FDM) technique. Scanning electron microscopy (SEM) images showed a satisfactory distribution of the fillers into the filaments and the printed objects. Furthermore, differential scanning calorimetry (DSC) measurements revealed that PLA/PCL filaments exhibit lower glass transition and melting point temperatures than the pure PLA filaments. Finally, piezoelectric and dielectric measurements of the 3D objects showed that composite PLA/PCL scaffolds containing HAp and BT exhibited piezoelectric coefficient (d33) values close to the human bone and high dielectric permittivity values
Analytical Framework for Coordinated Planning and Operation of Multicarrier Energy Systems
No full textLocal multicarrier energy systems (MCESs) offer a unique opportunity to exploit the synergies from the interplay of multiple energy carriers and utilize local renewables, thus increasing energy efficiency and supply reliability as well as reducing dependencies from the external networks. To make them sustainable not only from the energy and environmental perspective but also from the economic one and have a concrete option to the centralized energy systems based on fossil fuels, coordinated planning and operation on multiple time horizons is extremely important. This chapter covers all the transversal aspects related to this issue, by presenting a detailed analytical framework for the optimal design and operation of MCESs. First, the chapter presents the modeling of a wide range of generation, conversion, and storage technologies that can be part of MCESs. Then, the optimization frameworks for the design and the operation problems are established, by presenting several types of objective functions, constraints, and solution methodologies. The analytical frameworks are structured by covering different time horizons from long-term system planning to day-ahead and real-time operation. The effectiveness of the tools proposed to address each of these phases will be proved with a proper case study and discussion of simulation results. In addition, a critical overview of the current commercial tools available for the optimal design and operation of MCESs will be presented, by mapping them according to several criteria such as type, type of users, coverage of multicarrier aspects, objective functions, functionalities, mathematical approach, temporal resolution, and time horizons as well as pros and cons in their application to MCESs.©2024 Wiley. This is the peer reviewed version of the following article: Di Somma, M., Papadimitriou, C., Rousis, A. O., Patsidis, A., Shafie‐Khah, M., Shahbazbegian, V. & Askeland, M. (2024). Analytical Framework for Coordinated Planning and Operation of Multicarrier Energy Systems. In M. Di Somma, C. Papadimitriou, G. Graditi, & K. Kok (Eds.). Integrated Local Energy Communities: From Concepts and Enabling Conditions to Optimal Planning and Operation (pp. 187-224). Wiley-VCH Verlag, which has been published in final form at https://doi.org/10.1002/9783527843282.ch6. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.fi=vertaisarvioitu|en=peerReviewed
Epoxy-Based/BaMnO4 Nanodielectrics: Dielectric Response and Energy Storage Efficiency
No full textCompact capacitive energy storing/harvesting systems could play a key role in the urgent need for more energy-efficient technologies to address both energy and environmental issues. Therein, the purpose of the present work is to develop and investigate epoxy/BaMnO4 nanocomposites at various filler concentrations, which could be applicable as compact materials systems for energy storage and harvesting. Broadband dielectric spectroscopy was used for studying the dielectric properties and the relaxation processes of the examined nanodielectrics. The energy storing/retrieving ability of the nanocomposites was also evaluated via DC charge–discharge experiments. The coefficient of energy efficiency (neff) was found for all prepared nanocomposites to evaluate the energy performance of the systems. Dielectric data divulge the existence of two matrix-related relaxations, i.e., α-mode and β-mode, attributed to the glass-to-rubber transition of the polymer matrix and re-orientation of polar side groups, respectively. Interfacial polarization was also identified in the low-frequency and high-temperature region. The 7 phr BaMnO4 nanocomposite exhibits the best performance in terms of the stored and harvested energies compared to all systems. On the other hand, the 5 phr, 3 phr and 1 phr nanocomposites display optimum energy performance, reaching high values of neff
Dielectric Response of ZnO/PMMA Nanocomposites with Atmospheric Pressure Plasma-Modified Surfaces
No full textIn this work, the effect of etching the surface of polymer matrix nanocomposites with atmospheric pressure plasma targeting to achieve enhanced dielectric properties was investigated. Polymer nanocomposites, with varying reinforcing phase content, were modified by atmospheric-pressure plasma resulting in an increase in the surface filler’s concentration. Polymethyl methacrylate (PMMA) matrix nanocomposites reinforced with zinc oxide (ZnO) nanoparticles were prepared and dielectrically studied as a function of the nanoparticle content and the plasma modified surfaces. The electrical response of the composite systems was studied by means of Broadband Dielectric Spectroscopy (BDS) over a wide range of temperatures and frequencies. The dielectric permittivity increased with the embedded phase content and with plasma surface treatment. Energy density followed the same trend as dielectric permittivity, and the plasma-treated nanocomposite with the higher ZnO content exhibited approximately 27% higher energy density compared to the unreinforced matrix
Synthesis and Integration of an Fe(II) Coordination Compound into Green Resin Matrices for Multifunctional Dielectric, Piezoelectric, Energy Harvesting, and Storage Applications
No full textPolymer-based hybrid composites have emerged as promising platforms for multifunctional energy applications, combining structural versatility with tunable dielectric behavior. In this study, synthesized [Fe(bpy)3]SO4; (tris(2,2′-bipyridine)iron(II) sulfate) coordination compound was incorporated into a green epoxy resin matrix to fabricate nanocomposites aimed at enhancing dielectric permittivity (ε′), piezoelectric coefficient (d33, pC/N), energy-storage efficiency (nrel, %), and mechanical strength (σ, MPa). The integration of the Fe(II) complex via Scanning Electron Microscopy (SEM) confirmed a homogeneous dispersion within the matrix. Broadband Dielectric Spectroscopy (BDS) revealed the presence of three relaxation processes in the spectra of the tested systems, demonstrating enhanced dielectric permittivity with increasing Fe(II) content. Under progressively shorter relaxation times (τ, s), key processes such as interfacial polarization, the polymer matrix’s transition from a glassy to a rubbery state, and the dynamic reorganization of polar side groups along the polymer backbone are activated. The ability to store and retrieve electric energy was confirmed by varying filler content under direct current (dc) conditions. The nanocomposite with 10 phr (mass parts/100 mass parts of resin) filler achieved a piezoelectric coefficient of d33 = 5.1 pC/N, an energy-storage efficiency of nrel = 44%, and a tensile strength of σ = 55.5 MPa, all of which surpass values reported for conventional epoxy-based composites. These results confirm the ability of the system to store and retrieve electric energy under direct current (dc) fields, while maintaining mechanical robustness and thermal stability due to synergistic interactions between the epoxy matrix and the Fe(II) complex. The multifunctional behavior of the composites underscores their potential as advanced materials for integrated dielectric, piezoelectric, and energy storage and harvesting applications
