Despite growing interest in additive manufacturing for polymers, its industrial application is limited by a lack of suitable materials. In particular, Fused Filament Fabrication (FFF) relies primarily on amorphous or low-crystalline thermoplastics, most of which are not specifically functionalised. Although polypropylene (PP) is a widely used commodity, it still represents a challenge for FFF applications, mainly due to its semicrystalline nature and unfavourable rheological behaviour.

In this work, an effective strategy for obtaining 3D printable PP-based materials is proposed, also considering the possibility of exploiting the FFF technology for the obtainment of items endowed with specific functionalities and for upcycling purposes.

Firstly, a detailed rheological and thermal characterization of a series of PPs (both homopolymers and heterophasic copolymers) characterized by different viscosity and presence of fillers allowed for highlighting important microstructure/processabilty relationships, providing critical features for the design and development of 3D printable PP-based materials.

In a second step of the research, several kinds of micro- and nano-fillers were introduced within PP with the aim of providing the 3D printed samples with superior mechanical properties, flame retardancy or thermal conductivity.

Finally, recycled PP (r-PP) recovered from different streams was valorized through the formulation of filaments for FFF processes. In this context, on the basis of the known-how achieved in the previous research about PP printability, the formulation of r-PP deriving from municipal solid waste, e-waste or protective single-use face masks was optimized through the introduction of different types of fillers in order to adjust the rheological and thermal characteristics of the material for achieving a successful FFF process.

The obtained results showed that a proper modification of r-PP microstructure and a close optimization of the processing parameters allow for profitably, enhancing the value-added of r-PP and contributing to sustainable manufacturing practices.

Self-healing materials have garnered significant interest in the industry due to their potential for various applications, particularly in the automotive sector, including exterior parts and interior components. In this context, multiple strategies have been implemented to develop sustainable materials, especially for interior vehicle elements. Additionally, consumers demand constant improvements in material quality, as well as innovations in design, shapes, and colors.

In the automotive field, polylactic acid (PLA) has been proposed as a suitable material for this industry, with modifications or incorporations of other materials aimed at improving its properties. Self-healing polymers offer a good solution for maintaining the appearance of interior car components. By combining PLA with polycaprolactone (PCL), a more flexible material is obtained, and the incorporation of murexide (Mu) particles contributes to enhancing its self-healing capabilities.

To evaluate the properties of the resulting material, reactive extrusion was carried out using maleic anhydride as a grafting agent for PLA, likewise improving its compatibility with PCL and murexide (Mu) particles. Characterizations were performed using nuclear magnetic resonance (NMR), Fourier Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric / differential scanning calorimetry (TGA)/(DSC), and confocal laser scanning microscopy (CLSM) techniques to analyze the morphology, structure, and thermal behavior of the material. The observed results show that the extrusion process alters the system's crystallinity, favoring an amorphous structure and achieving adequate dispersion of the constituent materials. However, no significant changes were observed between the samples and the raw materials when analyzed by NMR and FT-IR. Based on the collection of all analyses, it can be inferred that a self-healing material is obtained, though further studies are required to confirm that the material meets the necessary properties.

Antibacterial fibers play a crucial role in enhancing hygiene, safety, and comfort in textiles. This study explores the monofilament melt spinning of polyethylene terephthalate (PET) composite fibers incorporating hybrid fillers of copper (Cu) and a low-melting-point alloy (In₅₁Bi_32.5Sn_16.5). The research evaluates the impact of these fillers on spinnability, morphology, thermal degradation, and electrical resistance of the melt spun fibers across various loading levels. A key motivation for this approach is the incorporation of copper as an embedded antimicrobial agent. Unlike surface-coated treatments, copper dispersed within the fiber matrix has the potential to deliver durable antimicrobial functionality, making these fibers particularly attractive for medical, hygienic, and performance textile applications. Additionally, the use of low melting alloy, which is significantly more cost-effective than copper, provides a low-cost pathway to functional fiber production without compromising melt processability. The study identifies some challenges but successful translation of polymer-metal composites from extrusion to continuous, spinnable monofilament fibers of good strength and well dispersed metal particles inside the polymer matrix. This work stands out as one of the few efforts to scale up lab-formulated composites into melt-spinnable and post-drawable monofilaments. Overall, the research lays a foundation for affordable, scalable antimicrobial fibers with potential applications in advanced textile systems.

The transition to a circular economy in packaging has become a strategic priority due to increasing regulatory pressure and environmental awareness. The use of bio-based and degradable, and/or recycled materials contributes to the development of sustainable, circular material flows. This has driven research into incorporating renewable components into polymer systems. Poly(vinyl alcohol) (PVOH), a water-soluble synthetic polymer with excellent film-forming properties, is particularly suitable for such enhancements due to its compatibility with natural additives.

In this study, we investigate the thermo-mechanical performance of PVOH films reinforced separately with lignin and nanocelluloses to assess their effectiveness in improving thermo-mechanical properties and increasing overall bio-based content.

PVOH composite films were prepared by solvent casting with varying loadings (5%, 10%, 20%) of lignin and nanocellulose. Hydropol™ PVOH was provided by Aquapack Polymers. Organosolv lignin was extracted from Jartropha Curcas L. seed coats, while enzymatic cellulose nanofibrils were obtained from bleached kraft pulp. Mechanical and thermal properties were evaluated using tensile testing and thermal analysis (DSC, TGA).

Results showed that 5% loading of both reinforcements improved the mechanical strength and thermal stability of PVOH films. Nanocellulose provided greater increase in tensile strength and modulus due to its high aspect ratio and strong hydrogen bonding with the PVOH. In contrast, lignin improved thermal stability while preserving the film’s flexibility, likely due to its aromatic, amorphous structure.

These findings reveal distinct reinforcement mechanisms, highlighting the potential for tailored material design based on specific performance needs. Overall, lignin and nanocellulose are promising sustainable reinforcements for PVOH films, advancing the development of high-performance, bio-based polymer composites.

Acknowledgments

RM is grateful for Grant RYC2021-034380-I funded by MCIN/AEI/10.13039/501100011033 and by European Union “NextGenerationEU”/PRTR. RM and GC also acknowledge funding from Aquapak Polymers.

Towards the development of sustainable and multifunctional materials, a hybrid polymer composite system composed of cellulose fiber, sodium alginate and titanium oxide (TiO₂) nanoparticles has been made in the form of beads. The cellulose fiber was extracted from Areca husk, an agricultural waste material. TiO₂ was made in nanosize by the green synthesis method using Azadirachta indica (neem) leaf extract. Hydrogel beads were fabricated from a mixture of sodium alginate, cellulose fiber, and TiO₂ nanoparticles by an ionic gelation process achieved using calcium chloride. The physicochemical characterization of the gel beads was carried out using FTIR, SEM, XRD, TGA, and TEM techniques. The pH-responsive swelling of the gel beads was demonstrated from the swelling studies carried out in aqueous medium under different pH conditions. The beads were evaluated for the slow release of bioactive agents, namely neem seed oil (NSO), a biopesticide and urea, and a fertilizer molecule. The loading and release of these agents were studied in an aqueous medium. The results indicated percentage loadings of 93.96% and 90.55% for neem seed oil and urea, respectively. The slow release of NSO and urea was observed to occur from the gel beads in a sustained manner during a 3-day period. The kinetic analysis of the release data indicated the release of both agents, following the Korsmeyer–Peppas model. The release exponent ‘n’ obtained from this model was less than 0.5 in both cases, indicating the release to be a Fickian process. The NSO- and urea-loaded gel beads were also evaluated for antibacterial characteristics against E. coli and S. aureus, and the results indicated the role of NSO in enhancing the antibacterial activity of the gel. Thus, this study exemplifies a sustainable approach to valorize agricultural waste for the development of smart materials in agricultural use.

Lignin is the second most abundant biopolymer in nature, after cellulose, and is found in the cell walls of various plant species (particularly in wood), agricultural residues, fruit peels, and other biopolymeric sources. This biopolymer has antioxidant and biodegradable properties, making it a valuable raw material for the development of highly functional bio-based materials. Therefore, this study focuses on the extraction of lignin from pecan nutshell (Carya illinoinensis) using the Organosolv technique. Additionally, its potential applications in the development of superhydrophobic surfaces are explored. The extracted lignin was characterized using UV-Vis spectrophotometry and scanning electron microscopy (SEM), which allowed the analysis of both its spectral composition and morphology. For the characterization of the superhydrophobic surfaces, optical microscopy and contact angle measurement techniques were employed to assess their surface structure and water repellency. The results showed that the extracted lignin presented well-defined bands in the wavelength range of 280 to 312 nm, similar to those of reference lignin. Furthermore, this lignin exhibited a morphology with poorly defined shapes and varying sizes. On the other hand, the superhydrophobic surfaces presented a heterogeneous structure and high contact angle values (> 150.10 ± 0.21), indicating high water repellency. Based on these results, it can be concluded that the extraction of lignin from agroindustrial residues, such as nutshells, is a sustainable and efficient strategy that not only enables the valorization of agroindustrial waste but also the production of a versatile biopolymer with potential applications in various fields. This approach promotes the use of more eco-friendly materials and contributes to the development of functional products, advancing towards a circular economy and reducing dependence on non-renewable resources.

This study investigated the formulation, ionic conductivity, swelling properties, thermosresponsive behavior of hydrogels made of Pluronic T908 and polyvinylpyrrolidone (PVP) and their ability to enhance the solubility of the widely used antibiotic Sulfadiazine (SDZ) in aqueous solutions. To maximize the circumstances to produce a homogenous hydrogel, different concentration ratios of the two polymers were assessed. Critical transitions depending on the composition and content of polymers were identified through mapping the phase behavior under controlled heating. Ionic conductivity experiments revealed that despite both polymers are nonionic, PVP could slightly increase the ionic mobility of H2O ions, on the other hand, T908rich formulations considerably increased ionic mobility and conductivity due to micelle formation. The Arrhenius equation was used to determine the activation energy (Ea) for ion transport, and the results showed that conductivity improved at intermediate T908: PVP ratios. T908 integration improved water uptake and decreased polymer rigidity, according to swelling studies; 30 wt.%T908 pure solution showed around four times higher swelling capacity than PVP solution at the same wt.%. And the solution mixture 25% T908 5% PVP showed the maximum water uptake among the evaluated mixture formulations.

After that, SDZ was loaded into variant formulations of T908 and PVP solutions and studies proved that both pure polymer solutions and mixtures of two polymers enhanced the solubility of SDZ in comparison to H2O alone. The combined findings of this study shed light on how to modify PVP-T908 hydrogels to be used in biomedical uses and medication delivery.

The polymer industry primarily relies on petroleum-based raw materials for polyurethane (PU) production. However, extensive research is being conducted to identify sustainable alternatives. This study explores the use of bio-based polyols derived from limonene and geraniol. Limonene is naturally sourced from citrus fruits like oranges, lemons, limes, and grapefruits, while geraniol is found in essential oils such as citronella, rose, and palmarosa oil. These renewable materials contribute to making the polymer industry more sustainable. In PU synthesis, isophorone diisocyanate (IPDI) and cyclohexyl diisocyanate (CHDI) are used. The structural characterization of polyols and PUs is carried out using Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). Mechanical properties, including tensile strength and hardness, are evaluated through standard testing methods, while thermal behavior is analyzed using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). DSC results indicate good miscibility of the synthesized PUs, with glass transition temperatures (Tg) of 75°C for IPDI-based PU and 64.47°C for CHDI-based PU. TGA analysis reveals that the thermal degradation of these PUs begins beyond 200°C. In mechanical testing, the highest recorded tensile strength was 36 MPa for IPDI-based PU, while CHDI-based PU exhibited a tensile strength of 26 MPa. Additionally, the hardness values were 85 for IPDI-based PU and 74 for CHDI-based PU. The gel fraction analysis, which assesses the degree of cross-linking, shows that IPDI-based PU has a higher cross-link density than CHDI-based PU. Overall, IPDI-based polyurethane demonstrates superior mechanical strength and thermal stability compared to its CHDI counterpart, making it a preferable option for applications that demand high-performance materials.

In this work, elastomeric composites based on hydrogenated nitrile butadiene rubber (HNBR) were obtained using both thermal and thermo-radiation vulcanization in the presence of two different fillers: clay and carbon black.

The main component is HNBR 3606. An elastomer mixture was obtained on laboratory rollers in sheet form with thickness of 2 mm. The thermal vulcanization process was carried out at 150 °C for 20 minutes. Radiation-thermal vulcanizates were obtained by preheating in an electric press at 150 °C for 5 minutes and in next step samples were exposed to 100, 200, 300 and 400 kGy doses of ionizing radiation. The goal was to estimate the effectiveness of the reinforcement of each filler under various conditions of vulcanization and determine the optimal dose of radiation to achieve maximum mechanical strength.

Experimental results showed that HNBR vulcanizates with carbon black consistently demonstrated higher tensile strength than samples with clay. This is explained by the strong interaction of carbon black particles with the elastomeric matrix, which contributes to the formation of a more homogeneous and densely crosslinked network. In contrast, samples filled with clay showed weaker interfacial bonding and lower stress transfer efficiency, leading to decrease in mechanical performances.

With an increase in the dose of radiation, the tensile strength of all samples increased, reaching a maximum at 300 kGy (optimal dose) due to an increase in the crosslinking density and the formation of a network structure. However, at a dose of 400 kGy, a slight decrease in strength was observed, probably caused by excessive chain scission and molecular degradation. Elongation at break showed the opposite trend, decreasing with the increase in radiation dose, which confirms the progressive strengthening of the network.

In recent years, the rapid advancement of electrochemical technologies—such as supercapacitors, fuel cells, and flexible energy storage—has intensified the search for new functional materials. Ionogels, hybrid systems combining ionic liquids and polymer matrices, have gained attention for their high ionic conductivity, mechanical flexibility, and chemical stability.

This study reports on the synthesis and characterization of ionogels containing 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIm FSI), aimed at evaluating their applicability as gel electrolytes in electrochemical capacitors. Various formulations were prepared using different monomer mixtures, and the most promising systems were selected based on visual inspection, conductivity, and mechanical properties.

The most notable result was the development of an ionogel based on Dymax XR-771-MS resin, which exhibited high ionic conductivity, excellent flexibility, and no ionic liquid leaching. The addition of thiol T2 significantly increased conductivity but reduced mechanical strength, especially in systems containing ≥85% IL, which showed low puncture resistance.

Mechanical tests showed that increasing IL content decreased Young’s modulus and tensile strength while enhancing elongation, indicating a trade-off between conductivity and durability. FTIR analysis confirmed efficient cross-linking through the disappearance of C=C bands after photopolymerization.

Electrochemical performance was evaluated in three capacitor configurations (IL+GF/A, gel+GF/A, gel+gel). Ionogel-based electrodes enabled pseudocapacitive effects associated with redox reactions, increasing capacitance. The gel+GF/A configuration offered the best performance, balancing conductivity with internal stability. Capacitance declined with increasing scan rate and current due to ion transport and redox kinetics limitations. High capacitance values in gel systems were attributed to pseudocapacitive contributions, dependent on accessible surface area and reaction dynamics.

Overall, the results show that EMIm FSI-based ionogels can be tailored for optimal performance by adjusting their composition, offering potential as safe and flexible electrolytes in electrochemical energy storage devices.

This work was supported by the Ministry of Science and Higher Education.