Institute of Fundamental Technological Research

Dobrzański J., Wojtacki K., Stupkiewicz S., Lamination-based efficient treatment of weak discontinuities for non-conforming finite element meshes, COMPUTERS AND STRUCTURES, ISSN: 0045-7949, DOI: 10.1016/j.compstruc.2023.107209, Vol.291, No.107209, pp.1-14, 2024

Abstract:
When modelling discontinuities (interfaces) using the finite element method, the standard approach is to use a conforming finite-element mesh in which the mesh matches the interfaces. However, this natural approach can prove cumbersome if the geometry is complex, in particular in 3D. In this work, we develop an efficient technique for a non-conforming finite-element treatment of weak discontinuities by using laminated microstructures. The approach is inspired by the so-called composite voxel technique that has been developed for FFT-based spectral solvers in computational homogenization. The idea behind the method is rather simple. Each finite element that is cut by an interface is treated as a simple laminate with the volume fraction of the phases and the lamination orientation determined in terms of the actual geometrical arrangement of the interface within the element. The approach is illustrated by several computational examples relevant to the micromechanics of heterogeneous materials. Elastic and elastic-plastic materials at small and finite strain are considered in the examples. The performance of the proposed method is compared to two alternative, simple methods showing that the new approach is in most cases superior to them while maintaining the simplicity.

Keywords:
Finite element method,Interface,Weak discontinuity,Laminate,Homogenization,Elasticity,Plasticity

Lavigne T., Bordas S., Lengiewicz J., Identification of material parameters and traction field for soft bodies in contact, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, ISSN: 0045-7825, DOI: 10.1016/j.cma.2023.115889, Vol.406, No.115889, pp.1-22, 2023

Abstract:
We provide an optimization framework that is capable of identifying the material parameters and contact traction field from two measured deformed geometries of a soft body in contact. The novelty of the framework is the idea of parametrizing the missing contact traction field and incorporating it into the inverse+forward hyper-elasticity formulation. We provide the continuum- and finite element formulation of the framework, as well as the direct differentiation method of sensitivity analysis to efficiently obtain necessary gradients for the BFGS optimizer. The correctness of the formulation and the excellent performance of the framework are confirmed by a series of benchmark numerical examples.

Keywords:
Hyper-elasticity, Inverse form, Large strains, Contact, Calibration, Soft bodies

Wichrowski M., Krzyżanowski P., Heltai L., Stupkiewicz S., Exploiting high-contrast Stokes preconditioners to efficiently solve incompressible fluid-structure interaction problems, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, ISSN: 0029-5981, DOI: 10.1002/nme.7350, Vol.124, pp.5446-5470, 2023

Abstract:
In this work, we develop a new algorithm to solve large-scale incompressible time-dependent fluid-structure interaction problems using a matrix-free finite element method in arbitrary Lagrangian–Eulerian frame of reference. We derive a semi-implicit time integration scheme which improves the geometry-convective explicit scheme for problems involving the interaction between incompressible hyperelastic solids and incompressible fluids. The proposed algorithm relies on the reformulation of the time-discrete problem as a generalized Stokes problem with strongly variable coefficients, for which optimal preconditioners have recently been developed. The resulting algorithm is scalable, optimal, and robust: we test our implementation on model problems that mimic classical Turek-Hron benchmarks in two and three dimensions, and investigate timing and scalability results.

Keywords:
arbitrary Lagrangian-Eulerian, finite element method, fluid-structure interaction, geometric multigrid, matrix-free method, monolithic scheme

Manjakkal L., Jain A., Nandy S., Goswami S., Carvalho J., Pereira L., See C., Pillai S., Hogg R., Sustainable electrochemical energy storage devices using natural bast fibres, Chemical Engineering Journal, ISSN: 1385-8947, DOI: 10.1016/j.cej.2023.142845, Vol.465, No.142845, pp.1-16, 2023

Abstract:
Naturally abundant materials play a crucial role in the development of sustainable electrochemical energy storage (EES) devices including batteries and supercapacitors (SCs). This is due to limited available resources with regards to energy storage materials, and the environmental pollution produced by the toxic materials utilized in conventional EESs. In the current review, development in the field of natural bast fibres (jute, flax, hemp and kenaf) based EES devices performances is highlighted. This review emphasizes methods such as the direct use of modified fibres and activated carbon from biomass for the design of EES devices. Activated fibres were developed using both physical and chemical activation methods. Key challenges including active electrode materials preparation, capacitive retention, and the implementation of the fibre based EES devices are critically discussed. Furthermore, the recent surge in the use of wearables and portable technologies that demand further development of flexible/non-flexible EES devices are also explored. Future trends and perspectives on materials development, power management interface, recycling, biodegradability and circular economy are also addressed. It is concluded that the development of new renewable energy systems using bast fibres has many remarkable advances in device performance. For this, an innovative approach is required to develop high energy density bast fibre based sustainable EES devices which will be potentially implemented for clean energy solutions.

Keywords:
Biomass derived carbon, Electrochemical energy storage, Supercapacitor, Modified fibres, Natural fibres

Milczarek M., Jarząbek D., Jenczyk P., Bochenek K., Filipiak M., Novel paradigm in AFM probe fabrication: Broadened range of stiffness, materials, and tip shapes, TRIBOLOGY INTERNATIONAL, ISSN: 0301-679X, DOI: 10.1016/j.triboint.2023.108308, Vol.180, No.108308, pp.1-12, 2023

Abstract:
Atomic force microscopes could be used in wide range of nanotribology experiments but probes available on the market are only made of silicon or silicon nitride with a stiffness in the range of 0.01–100 N/m, which significantly limits the possible research. We strive to solve this problem by designing all-metal probes. The proposed fabrication method is characterised by the use of a copper substrate and electrodeposition in a mould prepared by indentation and photolithography. Prototype probes fabricated with this method were made of nickel with a stiffness of 20 N/m and 2800 N/m and were used for topography and friction measurements. Both the method and all-metal probes showed flexibility and great potential, especially in the field of nano/microtribology.

Keywords:
Atomic force microscopy, Microfabrication, Cantilever, Metal probe, Friction, Nanotribology

Shih C.P., Krajewski M., Hasin P., Chen C.H., Lee C.Y., Lin J.Y., Spray-drying synthesis of fluorine-doped LiNi0.5Mn1.5O4 as high-voltage cathodes for lithium-ion batteries, JOURNAL OF ALLOYS AND COMPOUNDS, ISSN: 0925-8388, DOI: 10.1016/j.jallcom.2022.167641, Vol.932, No.167641, pp.1-13, 2023

Abstract:
In this current work, the pristine LiNi0.5Mn1.5O4 (LNMO) and fluorine-doped LiNi0.5Mn1.5O4–xFx (x = 0.1; 0.2; 0.3) cathode materials were successfully synthesized through a facile spray-drying method. The performed morphological and structural characterizations revealed that the fluorine doping led to a partial conversion of Mn4+ to Mn3+ ions in LNMO structure and an increase of their average particle sizes. These characteristics made the LiNi0.5Mn1.5O3.9F0.1 cathode exhibited the best rate capability at high C-rates and cycling performance among all investigated LNMO-based electrodes. Its improved electrochemical properties resulted from excellent crystallinity, high Li+ diffusion coefficient, and low charge-transfer resistance. Moreover, the LiNi0.5Mn1.5O3.9F0.1 electrode was found to possess the excellent resistant against Mn dissolution at elevated temperature. According to its great thermal stability, an impressive capacity retention of 81.5% after 100-cycle at 0.2 C at elevated temperature was achieved. In terms of the facile synthesis approach, superior electrochemical performances, and great thermal stability, the LiNi0.5Mn1.5O3.9F0.1 electrode synthesized by the scalable spray-drying method can be regarded as a promising high-voltage cathode material for high-performance Li-ion batteries.

Keywords:
Cathode material, Fluorine doping, Spinel LiNi0.5Mn1.5O4, Spray-drying synthesis, Li-ion batteries

Golasiński K., Maj M., Urbański L., Staszczak M., Gradys A.D., Pieczyska E.A., Experimental study of thermomechanical behaviour of Gum Metal during cyclic tensile loadings: the quantitative contribution of IRT and DIC, Quantitative InfraRed Thermography Journal, ISSN: 1768-6733, DOI: 10.1080/17686733.2023.2205762, pp.1-18, 2023

Abstract:
Thermomechanical behaviour of Gum Metal (Ti–23Nb–0.7Ta–2.0Zr–1.2O, at.%) under cyclic tension was experimentally investigated using infrared thermography and digital image correlation. The thermomechanical characteristics of particular stages of the subsequent loading-unloading cycles of Gum Metal were identified, i.e. (I) the linear, elastic loading accompanied by the temperature drop, (II) the nonlinear super-elastic loading related to the temperature growth, (III) the transient stage (at which both the superelastic-like behaviour and the plastic one are present simultaneously) and the temperature starts growing fast, (IV) the plastic deformation with a significant growth of temperature, (V) the superelastic-like unloading accompanied by a fast drop in temperature, (VI) the transient unloading with a slower decrease in temperature and (VII) the elastic unloading, with a slight increase in temperature. Thermoelastic effect in Gum Metal during both loading and unloading was analysed in each tensile cycle. Finally, the evolution of strain and temperature fields just before unloading in each cycle was discussed and a comparison of the fields at selected stages of cycles 12 and 24 was presented. The results of this work enabled us to identify the non-dissipative processes of elastic and superelastic-like deformations as well as the dissipative process of plastic deformation.

Keywords:
Gum Metal,β-Ti alloy,cyclic tension,superelasticity,thermoelastic effect,infrared thermography,digital image correlation

Rezaee Hajidehi M., Tůma K., Stupkiewicz S., Indentation-induced martensitic transformation in SMAs: Insights from phase-field simulations, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, ISSN: 0020-7403, DOI: 10.1016/j.ijmecsci.2023.108100, Vol.245, No.108100, pp.1-15, 2023

Abstract:
Direct experimental characterization of indentation-induced martensitic microstructures in pseudoelastic shape memory alloys (SMAs) is not possible, and thus there is a lack of evidence and understanding regarding the microstructure pattern and related features. To fill this gap, in this work we employ the phase-field method to provide a detailed and systematic analysis of martensitic phase transformation during nanoindentation. A recently-developed finite-element-based computational model is used for this purpose, and a campaign of large-scale 3D simulations is carried out. First, the orientation-dependent indentation response in CuAlNi (a widely studied SMA) is examined. A detailed investigation of the predicted microstructures reveals several interesting features, some of them are consistent with theoretical predictions and some can be (to some extent) justified by experiments other than micro/nanoindentation. The results also highlight the key role of finite-deformation effects and elastic anisotropy of the phases on the model predictions. Next, a detailed study of indentation-induced martensitic transformation in NiTiPd (a potential low-hysteresis SMA) with varying Pd content is carried out. In terms of hysteresis, the results demonstrate the prevailing effect of the transformation volume change over phase compatibility in the conditions imposed by nanoindentation and emphasize on the dominant role of the interfacial energy at small scales. Results of such scope have not been reported so far.

Keywords:
Nanoindentation,Pseudoelasticity,Twinning,Microstructure formation,Phase-field method

Mróz Z., Paczelt I., Kucharski S.J., Contact interaction and wear of beam supports resting on a frictional substrate, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, ISSN: 0020-7403, DOI: 10.1016/j.ijmecsci.2023.108628, Vol.260, No.108628, pp.1-16, 2023

Abstract:
The frictional contact response of a beam with attached spherical indenters and supported on a plane substrate is considered for periodically varying normal load. An oblique loading case then occurs as the structural load induces both normal and tangential forces on the contact zone. The cyclic tangential sliding and spin of indenter on the substrate are then accompanied by evolving contact zone related to load variation. Rigid-sliding and slip-sliding friction models have been used to describe analytically cyclic contact response, load-deflection hysteretic relation, wear scar evolution and dissipated energy per cycle assuming linear-elastic material model. The analytical solution has been verified by experimental tests providing data on mechanical response, load-deflection diagrams illustrating transient and steady states and wear scar evolution. The effect of wear debris adhesively bonded to the indenter was found to be essential for increasing friction and wear. The relation of wear volume to the dissipated energy is presented. The analysis is aimed to develop a new type of wear tester applicable to oblique loading cases

Keywords:
Frictional contact, Oblique loading, Friction models, Hysteretic diagrams, Wear growth

Virupakshi S., Kowalczyk-Gajewska K., Cylindrical void growth vs. grain fragmentation in FCC single crystals: CPFEM study for two types of loading conditions, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2023.112397, Vol.280, pp.112397-1-112397-19, 2023

Abstract:
The crystal plasticity finite element method (CPFEM) is used to investigate the coupling between the cylindrical void growth or collapse and grain refinement in face-centred cubic (FCC) single crystals. A 2D plane strain model with one void is used. The effect of the initial lattice orientation, similarities, and differences between
stress- and strain-driven loading scenarios are explored. To this end, boundary conditions are enforced in two different ways. The first one is based on maintaining constant in-plane stress biaxiality via a dedicated truss element, while the second one is imposing a constant displacement biaxiality factor. Uniaxial and biaxial
loading cases are studied. For the uniaxial loading case a special configuration, which enforces an equivalent pattern of plastic deformation in the pristine crystal, is selected in order to investigate the mutual interactions between the evolving void and the developed lattice rotation heterogeneity. Next, biaxial loading cases are
considered for three crystal orientations, one of which is not symmetric with respect to loading directions. It is analysed how stress or strain biaxility factors and initial lattice orientation influence the void evolution in terms of its size and shape. Moreover, the consequences of variations in the resulting heterogeneity of lattice rotation are studied in the context of the grain refinement phenomenon accompanying the void evolution. Scenarios that may lead to more advanced grain fragmentation are identified.

Keywords:
Crystal plasticity , Finite element method, Void evolution, Grain refinement

Rezaee Hajidehi M., Stupkiewicz S., Predicting transformation patterns in pseudoelastic NiTi tubes under proportional axial–torsion loading, INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES, ISSN: 0020-7683, DOI: 10.1016/j.ijsolstr.2023.112436, Vol.281, No.112436, pp.1-30, 2023

Abstract:
We present a comprehensive modeling study on the patterns of propagating instabilities in NiTi tubes under proportional axial–torsion loading. Our study directly refers to the experimental work of Reedlunn et al. (2020), with a particular focus on the unique longitudinal transformation bands that occur in torsion-dominated loading paths. A previously-developed gradient-enhanced model of pseudoelasticity is employed and is adapted to incorporate the residual stresses. In addition, our finite-element setup accounts for the impact of collet grips on the NiTi tubes via a simplified frictional contact model. The results demonstrate the capability of the model in capturing subtle features of the transformation patterns observed in the experiment, including the multi-finger fronts in tension-dominated loading and longitudinal bands in torsion-dominated loading. Our study suggests that the combination of the residual stresses and the collet grips facilitates the formation of longitudinal bands.

Keywords:
Shape memory alloys, Phase transformation, Strain localization, Propagating instabilities, Finite-element method

Nabavian Kalat M., Staszczak M., Urbański L., Fernandez C., Vega C., Cristea M., Ionita D., Lantada A., Pieczyska E.A., Investigating a shape memory epoxy resin and its application to engineering shape-morphing devices empowered through kinematic chains and compliant joints, MATERIALS AND DESIGN, ISSN: 0264-1275, DOI: 10.1016/j.matdes.2023.112263, Vol.233, No.112263, pp.1-15, 2023

Abstract:
4D printing is the additive manufacturing (3D printing) of objects that can transform their shape in a controlled and predictable way when subjected to external stimuli. A thermo-responsive shape memory polymer (SMP) is a highly suitable material to 4D print smart devices, due to its actuation function and the capability of recovering its original shape from the deformed one upon heating. This study presents the results of employing an epoxy resin in the additive manufacturing of complex-shaped smart devices with shape-morphing properties using laser stereolithography (SLA). To quantify the shape memory behaviour of the shape memory epoxy (SMEp), we first investigate the thermomechanical properties of the 3D-printed specimens in a tensile testing machine coupled with an environmental thermal chamber. This approach allows us to determine the shape fixity and recovery of SMEp. Next, we propose effective designs of complex-shaped devices, with the aim of promoting shape morphing through micro-actuators and compliant joints acting as active regions in combination with multiplying mechanisms or kinematic chains in each of the devices. We manufacture the complex-shaped prototypes by using SLA directly from the computer-aided designs. The shape memory trials of the 3D-printed prototypes reveal quite precise shape recovery of the devices, illustrating their shape-memory. In fact, the inclusion of micro-actuators and compliant joints within the complex-geometry devices allows for local triggering, deformation and recovery, resulting in a prompt response of the devices to heat. Therefore, innovative designs, along with the suitable smart material and high-quality manufacturing process, lead to 4D printed devices with fast actuation and shape-morphing properties. Overall, this research may contribute to the development of smart materials and 4D printing technology for applications in fields such as biomedical engineering, robotics, transport and aerospace engineering

Keywords:
Shape memory polymers,Shape memory epoxy,Shape morphing structures,Laser stereolithography,3D and 4D printing

Abramowicz M., Osial M., Urbańska W., Walicki M., Wilczewski S., Pręgowska A., Skórczewska K., Jenczyk P., Warczak M., Pisarek M., Giersig M., Upcycling of Acid-Leaching Solutions from Li-Ion Battery Waste Treatment through the Facile Synthesis of Magnetorheological Fluid, Molecules, ISSN: 1420-3049, DOI: 10.3390/molecules28062558, Vol.28, No.6, pp.2558-1-2558-16, 2023

Abstract:
The rapidly growing production and usage of lithium-ion batteries (LIBs) dramatically raises the number of harmful wastes. Consequently, the LIBs waste management processes, taking into account reliability, efficiency, and sustainability criteria, became a hot issue in the context of environmental protection as well as the scarcity of metal resources. In this paper, we propose for the first time a functional material—a magnetorheological fluid (MRF) from the LIBs-based liquid waste containing heavy metal ions. At first, the spent battery waste powder was treated with acid-leaching, where the post-treatment acid-leaching solution (ALS) contained heavy metal ions including cobalt. Then, ALS was used during wet co-precipitation to obtain cobalt-doped superparamagnetic iron oxide nanoparticles (SPIONs) and as an effect, the harmful liquid waste was purified from cobalt. The obtained nanoparticles were characterized with SEM, TEM, XPS, and magnetometry. Subsequently, superparamagnetic nanoparticles sized 15 nm average in diameter and magnetization saturation of about 91 emu g−1 doped with Co were used to prepare the MRF that increases the viscosity by about 300% in the presence of the 100 mT magnetic fields. We propose a facile and cost-effective way to utilize harmful ALS waste and use them in the preparation of superparamagnetic particles to be used in the magnetorheological fluid. This work describes for the first time the second life of the battery waste in the MRF and a facile way to remove the harmful ingredients from the solutions obtained after the acid leaching of LIBs as an effective end-of-life option for hydrometallurgical waste utilization.

Keywords:
environment protection SPION, battery waste, toxic waste management, direct recycling, sustainability, circular economy, critical raw materials

Wilczewski S.^♦, Skórczewska K., Tomaszewska J., Osial M., Dąbrowska A., Nikiforow K., Jenczyk P., Grzywacz H., Graphene Modification by Curcuminoids as an Effective Method to Improve the Dispersion and Stability of PVC/Graphene Nanocomposites, Molecules, ISSN: 1420-3049, DOI: 10.3390/molecules28083383, Vol.28, No.8, pp.1-25, 2023

Keywords:
graphene, curcuminoids, poly(vinyl chloride), nanocomposites stability, polymer films

Maj P., Bochenek K., Sitek R., Koralnik M., Jonak K., Wieczorek M., Pakieła Z., Mizera J., Comparison of mechanical properties and structure of Haynes 282 consolidated via two different powder metallurgy methods: laser powder bed fusion and hot pressing, ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING, ISSN: 1644-9665, DOI: 10.1007/s43452-023-00674-y, Vol.23, No.130, pp.1-11, 2023

Abstract:
The development of powder metallurgy methods in recent years has caused traditional casting methods to be replaced in many industrial applications. Using such methods, it is possible to obtain parts having the required geometry after a process that saves both manufacturing costs and time. However, there are many material issues that decrease the functionality of these methods, including mechanical properties anisotropy and greater susceptibility to cracking due to chemical segregation. The main aim of the current article is to analyze these issues in depth for two powder metallurgy manufacturing processes: laser powder bed fusion (LPBF) and hot-pressing (HP) methods—selected for the experiment because they are in widespread use. Microstructure and mechanical tests were performed in the main manufacturing directions, X and Z. The results show that in both powder metallurgy methods, anisotropy was an issue, although it seems that the problem was more significant for the samples produced via LPBF SLM technique, which displayed only half the elongation in the building direction (18%) compared with the perpendicular direction (almost 38%). However, it should be noted that the fracture toughness of LPBF shows high values in the main directions, higher even than those of the HP and wrought samples. Additionally, the highest level of homogeneity even in comparison with wrought sample, was observed for the HP sintered samples with equiaxed grains with visible twin boundaries. The tensile properties, mainly strength and elongation, were the highest for HP material. Overall, from a practical standpoint, the results showed that HP sintering is the best method in terms of homogeneity based on microstructural and mechanical properties.

Keywords:
Haynes 282 nickel alloy, LPBF, HP, SEM , Static tensile test

Jain A., Ziai Y., Bochenek K., Manippady Sai R., Pierini F., Michalska M., Utilization of compressible hydrogels as electrolyte materials for supercapacitor applications, RSC Advances, ISSN: 2046-2069, DOI: 10.1039/d3ra00893b, Vol.13, pp.11503-11512, 2023

Abstract:
Utilization of CoO@Co3O4-x-Ag (x denotes 1, 3, and 5 wt% of Ag) nanocomposites as supercapacitor electrodes is the main aim of this study. A new low-temperature wet chemical approach is proposed to modify the commercial cobalt oxide material with silver nanoparticle (NP) balls of size 1–5 nm. The structure and morphology of the as-prepared nanocomposites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption–desorption measurements. Hydrogels known to be soft but stable structures were used here as perfect carriers for conductive nanoparticles such as carbons. Furthermore, hydrogels with a large amount of water in their network can give more flexibility to the system. Fabrication of an electrochemical cell can be achieved by combining these materials with a layer-by-layer structure. The performance characteristics of the cells were examined by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge discharge (GCD). Cobalt oxide modified with 5 wt% Ag gave the best supercapacitor results, and the cell offers a specific capacitance of ∼38 mF cm−2 in two-electrode configurations.

Amini S., Rezaee Hajidehi M., Stupkiewicz S., Energy and morphology of martensite–twinned martensite interface in CuAlNi shape memory alloy: A phase-field study, COMPUTATIONAL MATERIALS SCIENCE, ISSN: 0927-0256, Vol.230, pp.112472-1-13, 2023

Abstract:
Needle-like twins are observed experimentally within the transition layer at the martensite–twinned martensite interface. We utilize a phase-field approach to investigate this microstructure. Our goal is to simulate the morphology of the transition layer and to perform a detailed analysis to characterize its interfacial and elastic micro-strain energy. To illustrate the micromechanical framework developed for that purpose, sample computations are carried out for a CuAlNi shape memory alloy undergoing a cubic-to-orthorhombic martensitic transformation. A particular focus of the study is on size-dependent morphology through examining the impact of twin spacing. Additionally, our results reveal that certain twin volume fractions lead to the emergence of twin branching as a way to minimize the total free energy stored in the microstructure.

Keywords:
Microstructure,Martensitic transformation,Transition layer,Phase-field method,Size effects

Petryk H., Kursa M., Energy approach to the selection of deformation pattern and active slip systems in single crystals, EUROPEAN JOURNAL OF MECHANICS A-SOLIDS, ISSN: 0997-7538, DOI: 10.1016/j.euromechsol.2023.105040, pp.1-15, 2023

Abstract:
The recently introduced quasi-extremal energy principle for incremental non-potential problems in rate-independent plasticity is applied to select the deformation pattern and active slip systems in single crystals. The standard crystal plasticity framework with a non-symmetric slip-system interaction matrix at finite deformation is used. The incremental work criterion for the formation of deformation bands is combined with the quasi-extremal energy principle for determining the active slip systems and slip increments in the bands. In this way, the incremental energy minimization approach has been extended to the non-potential problem of deformation banding in metal single crystals. It is shown that fulfilment of the mathematical criterion for incipient deformation banding in a homogeneous crystal in the multiple-slip case under certain conditions requires non-positive determinant of the hardening moduli matrix. Numerical examples of energetically preferable patterns of deformation bands are presented for Cu and Ni single crystals.

Keywords:
Solids, Plasticity, Crystal plasticity, Material stability, Slip-system selection, Energy minimization, Quasi-minimization, Time integration, Implicit, Channel-die, Deformation band

Pietrzyk-Thel P., Osial M., Pręgowska A., Abramowicz M., Nguyen Thu P., Urbańska W., Giersig M., SPIONs doped with cobalt from the Li-ion battery acid leaching waste as a photocatalyst for tetracycline degradation - synthesis, characterization, DFT studies, and antibiotic treatment, Desalination and Water Treatment, ISSN: 1944-3994, DOI: 10.5004/dwt.2023.29795, Vol.305, pp.155-173, 2023

Keywords:
Spent lithium-ion batteries, LiBs, Acid leaching, SPION, Magnetic nanomaterials, Metals recovery, Superparamagnetic, Waste management, Functional materials

Peringath Anjana R., Haghighat Bayan Mohammad A., Beg M., Jain A., Pierini F., Gadegaard N., Hogg R., Manjakkal L., Chemical synthesis of polyaniline and polythiophene electrodes with excellent performance in supercapacitors, Journal of Energy Storage, ISSN: 2352-152X, DOI: 10.1016/j.est.2023.108811, Vol.73, No.Part A, pp.108811-1-9, 2023

Abstract:
The emergence of portable electronics in miniaturized and intelligent devices demands high-performance supercapacitors (SC) and batteries as power sources. For the fabrication of such energy storage devices, conducting polymers (CPs) have significant advantages due to their high theoretical capacitive performance and conductivity. In this work, we developed two CPs including polyaniline and polythiophene through a low-cost chemically synthesized approach and the film-by-spin coating method. The structural and morphological properties of the CPs are analyzed using Fourier-transform infrared spectroscopy (FTIR), contact angle measurement, and scanning electron microscopy (SEM). Based on these CPs, novel pristine polyaniline and polythiophene-based SCs (PASC and PTSC) are developed. The prepared CPs contribute to high electrochemical performances due to their high conductive nature of the electrode and conjugated polymer materials reaction. Hence both electrochemical double-layer formation and pseudocapacitance contributed to the energy-storing performances of the device. Electrochemical impedance spectroscopic analysis (0.1 Hz to 100 kHz) demonstrates faster ionic exchange and high capacitance of the PASC electrode as compared to PTSC in H3PO4 electrolyte. The PASC devices exhibit specific capacitance of 13.22 mF·cm−2 with energy and power densities of 1.175 μW·h·cm−2 and 4.99 μW·cm−2 at a current of 50 μA. Compared to PTSC (specific capacitance 3.30 mF·cm−2) the PASC shows four times higher specific capacitance due to its improved surface, structural and electrical properties. The electrochemical performance reveals the superior SC performance for this type of CP electrode.

Keywords:
Conductive polymers, Spin coating, Polyaniline, Polythiophene, Supercapacitor, Electrochemical performances

Manippady S., Michalska M., Krajewski M., Bochenek K., Basista M.A., Zaszczyńska A., Czeppe T., Rogal , Jain A., One-step synthesis of a sustainable carbon material for high performance supercapacitor and dye adsorption applications, Materials Science and Engineering: B, ISSN: 0921-5107, DOI: 10.1016/j.mseb.2023.116766, Vol.297, No.116766, pp.1-14, 2023

Abstract:
The sustainable transformation of bio-waste into usable, material has gained great scientific interest. In this paper, we have presented preparation of an activated carbon material from a natural mushroom (Suillus boletus) and explor its properties for supercapacitor and dye adsorption applications. The produced cell exhibited a single electrode capacitance of ∼247 F g−1 with the energy and power density of ∼35 Wh kg−1 and 1.3 kW kg−1, respectively. The cell worked well for ∼20,000 cycles with ∼30% initial declination in capacitance. Three cells connected in series glowed a 2.0 V LED for ∼1.5 min. Moreover, ultrafast adsorption of methylene blue dye onto the prepared carbon as an adsorbent was recorded with ∼100% removal efficiency in an equilibrium time of three minutes. The performed tests indicate that the mushroom-derived activated carbon has the potential to become a high-performance electrode material for supercapacitors and an adsorbent for real-time wastewater treatment applications.

Keywords:
Activated carbon, Amorphous material, Biomass, Polymer gel electrolyte, Supercapacitor, Dye adsorption

Krajewski M., Pietrzyk P., Osial M., Liou S., Kubacki J., Iron–Iron Oxide Core–Shell Nanochains as High-Performance Adsorbents of Crystal Violet and Congo Red Dyes from Aqueous Solutions, LANGMUIR, ISSN: 0743-7463, DOI: 10.1021/acs.langmuir.3c00967, Vol.39, No.23, pp.8367-8377, 2023

Abstract:
The main aim of this work was to use the iron–iron oxide nanochains (Fe NCs) as adsorbents of the carcinogenic cationic crystal violet (CV) and anionic Congo red (CR) dyes from water. The investigated adsorbent was prepared by a magnetic-field-induced reduction reaction, and it revealed a typical core–shell structure. It was composed of an iron core covered by a thin Fe3O4 shell (<4 nm). The adsorption measurements conducted with UV–vis spectroscopy revealed that 15 mg of Fe NCs constituted an efficient dose to be used in the CV and CR treatment. The highest effectiveness of CV and CR removal was found for a contact time of 90 min at pH 7 and 150 min at pH 8, respectively. Kinetic studies indicated that the adsorption followed the pseudo-first-order kinetic model. The adsorption process followed the Temkin model for both dyes taking into account the highest value of the R2 coefficient, whereas in the case of CR, the Redlich–Peterson model could be also considered. The maximal adsorption capacity estimated from the Langmuir isotherms for the CV and CR was 778.47 and 348.46 mg g–1, respectively. Based on the Freundlich model, both dyes adsorbed on the Fe NCs through chemisorption, but Coulombic interactions between the dye and adsorbent cannot be excluded in the case of the CV dye. The obtained results proved that the investigated Fe NCs had an excellent adsorption ability for both dye molecules within five cycles of adsorption/desorption, and therefore, they can be considered as a promising material for water purification and environmental applications.

Frydrych K., Dominguez-Gutierrez F., Alava M., Papanikolaou S., Multiscale nanoindentation modelling of concentrated solid solutions: A continuum plasticity model, MECHANICS OF MATERIALS, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2023.104644, Vol.181, No.104644, pp.1-12, 2023

Abstract:
Recently developed single-phase concentrated solid-solution alloys (CSAs) contain multiple elemental species in high concentrations with different elements randomly arranged on a crystalline lattice. These chemically disordered materials present excellent physical properties, including high-temperature thermal stability and hardness, with promising applications to industries at extreme operating environments. The aim of this paper is to present a continuum plasticity model accounting for the first time for the behaviour of a equiatomic five-element CSA, that forms a face-centred cubic lattice. The inherent disorder associated with the lattice distortions caused by an almost equiatomic distribution of atoms, is captured by a single parameter that quantifies the relative importance of an isotropic plastic contribution to the model. This results in multiple plasticity mechanisms that go beyond crystallographic symmetry-based ones, common in the case of conventional single element metals. We perform molecular dynamics simulations of equiatomic CSAs: NiFe, NiFeCr, NiFeCrCo, and Cantor alloys to validate the proposed continuum model which is implemented in the finite element method and applied to model nanoindentation tests for three different crystallographic orientations. We obtain the representative volume element model by tracking the combined model yield surface.

Keywords:
High entropy alloys, Nanoindentation, Molecular dynamics, Finite element method, Crystal plasticity

N’souglo Komi E., Kowalczyk-Gajewska K., Marvi-Mashhadi M., Rodríguez-Martínez Jose A., The effect of initial texture on multiple necking formation in polycrystalline thin rings subjected to dynamic expansion, MECHANICS OF MATERIALS, ISSN: 0167-6636, DOI: 10.1016/j.mechmat.2023.104616, Vol.181, pp.104616-1-104616-18, 2023

Abstract:
In this paper, we have investigated, using finite element calculations, the effect of initial texture on the formation of multiple necking patterns in ductile metallic rings subjected to rapid radial expansion. The mechanical behavior of the material has been modeled with the elasto-viscoplastic single crystal constitutive model developed by Marin (2006). The polycrystalline microstructure of the ring has been generated using random Voronoi seeds. Both 5000 grain and 15000 grain aggregates have been investigated, and for each polycrystalline aggregate three different spatial distributions of grains have been considered. The calculations have been performed within a wide range of strain rates varying from to , and the rings have been modeled with four different initial textures: isotropic texture, Goss texture, R Goss texture and Z fiber texture. The finite element results show that: (i) the spatial distribution of grains affects the location of the necks, (ii) the decrease of the grain size delays the formation of the necking pattern and increases the number of necks, (iii) the initial texture affects the number of necks, the location of the necks, and the necking time, (iv) the development of the necks is accompanied by a local increase of the slip activity. This work provides new insights into the effect of crystallographic microstructure on dynamic plastic localization and guidelines to tailor the initial texture in order to delay dynamic necking formation and, thus, to improve the energy absorption capacity of ductile metallic materials at high strain rates.

Keywords:
Dynamic necking, Inertia, Crystal plasticity, Texture, Finite elements

Krajewski M., Liou S., Kubacki J., Investigation of iron oxide shell and iron core in magnetically-assisted synthetized wire-like nanochains, NANOTECHNOLOGY, ISSN: 0957-4484, DOI: 10.1088/1361-6528/acd38a, Vol.34, No.32, pp.325701-1-325701-7, 2023

Abstract:
The zerovalent iron (Fe0) nanomaterials tend to be spontaneously oxidized in the presence of oxygen. This leads to the formation of interface composed of iron core and thin iron oxide shell. These structures are frequently observed with transmission electron microscope but, at the same time, it is hard to determine the precise structural and chemical composition of oxide shell. This feature is very important for possible applications of Fe0 nanostructures. Hence, the present work aims to deliver more detailed insights in this topic. The investigations are performed for the iron nanochains prepared in the magnetic-field-induce reduction of FeCl3 by NaBH4. The high-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoemission spectroscopy confirm that the iron nanochains are covered by very thin oxide layer not exceeding over 3 nm. Moreover, the detailed XPS analyses of O 1s and Fe 2p lines indicate that the iron oxide shell reveals Fe3O4 nature. Moreover, this work demonstrated that some by-products of the reaction containing boron are presented in the sample even after a removal of the thin iron oxide shell by Ar+ treatment.

Keywords:
iron nanochains, magnetic-field-induced synthesis, surface oxidation, x-ray photoemission spectroscopy

Olusegun S., Osial M., Majkowska-Pilip A., Żelechowska-Matysiak K., Nieciecka D., Krajewski M.^♦, Pękała M., Krysiński P., Synthesis and characterization of Sr2+ and Gd3+ doped magnetite nanoparticles for magnetic hyperthermia and drug delivery application, CERAMICS INTERNATIONAL, ISSN: 0272-8842, DOI: 10.1016/j.ceramint.2023.03.102, pp.1-10, 2023

Abstract:
Commendable efforts have been gingered towards the fight against cancer. Nevertheless, it remains a major public health concern due to its predominant cause of death globally. Given this, we synthesized two different nanoparticles, Sr2+ and Gd3+ doped magnetite for magnetic hyperthermia and drug delivery application. Based on the characterization, the diffractogram shows that only one phase related to magnetite with a crystallite size of 10 nm was formed. TEM images revealed nanoparticles of spherical shapes of approximately 12 nm. There is no difference in magnetic saturation of the as-received synthesized samples (Fe3O4@Sr and Fe3O4@Gd), while the BET-specific surface area of Fe3O4@Gd is 8 m2 g−1 higher than Fe3O4@Sr. The heat generation in alternating magnetic field (the magnetic hyperthermia) of Fe3O4@Sr functionalized with citric acid and loaded with 5- fluorouracil (Fe3O4@Sr@CA@5-flu) is slower than Fe3O4@Gd@CA@5-flu. The specific absorption rate (SAR) of Fe3O4@Gd@CA@5-flu, 112.0 ± 10.4 W g−1 was found to be higher than that of Fe3O4@Sr@CA@5-flu. The thermogram shows that 11% of the drug was successfully loaded on Fe3O4@Gd@CA@5-flu. The release of the antitumor drug by the synthesized nanoparticle drug carriers for ovarian cancer (SKOV-3 cells) therapy showed that more than 50% of the cancer cell’s viability was reduced after 72 h of incubation. The synthesized nanoparticles demonstrated a promising drug carrier for the treatment of SKOV-3 cells.

Krajewski M., Witowski A., Liou S., Maj M., Tokarczyk M., Wasik D., Poly(vinylidene fluoride-co-hexafluoropropylene) films filled in iron nanoparticles for infrared shielding applications, Macromolecular Rapid Communications, ISSN: 1022-1336, DOI: 10.1002/marc.202300038, No.2300038, pp.1-7, 2023

Abstract:
In order to use the infrared (IR) radiation shielding materials, they should take a form of thin film coatings deposited on glass/polymer substrates or be used as fillers of glass/polymer. The first approach usually suffers from several
technological problems. Therefore, the second strategy gains more and more attention. Taking into account this trend, this work presents the usage of iron nanoparticles (Fe NPs) embedded into the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films as the shielding material in near-infrared (NIR) and mid-infrared (MIR) region. The performed
investigations show that the transmittance of copolymer films decreases with
increasing content of the Fe NPs inside them. It is found that the average fade of IR transmittance for 1, 2.5, 5, 10, and 50 mg of Fe NPs is about 13%, 24%, 31%, 77%, and 98%, respectively. Moreover, it is observed that the PVDF-HFP films filled in the Fe NPs almost does not reflect the NIR and MIR radiation. Hence, the IR shielding properties of the PVDF-HFP films can be effectively tuned by the addition of proper amount of the Fe NPs. This, in turn, shows that the PVDF-HFP films filled in the Fe NPs constitute a great option for IR antireflective and shielding applications.

Keywords:
antireflective materials, copolymer films, infrared radiation shielding materials, iron nanoparticles, nanofillers

Manecka-Padaż A., Jenczyk P., Pęcherski R., Nykiel A., Experimental investigation of Euler’s elastica: in-situ SEM nanowire post-buckling, BULLETIN OF THE POLISH ACADEMY OF SCIENCES: TECHNICAL SCIENCES, ISSN: 0239-7528, DOI: 10.24425/bpasts.2022.143648, Vol.70(6), No.e143648, pp.1-6, 2023

Abstract:
An in-situ nanoindenter with a flat tip was employed to conduct buckling tests of a single nanowire with simultaneous SEM imaging. A series of SEM images allowed us to calculate deflection. The deflection was confronted with the mathematical model of elastica. The post-buckling behaviour of nanowires is conducted in the framework of the nonlinear elasticity theory. Results show the significant effect of geometrical parameters on the stability of buckled nanowires.

Keywords:
post-buckling, nanowire, nanomechanics

Darban H., Luciano R., Darban R., Buckling of cracked micro- and nanocantilevers, ACTA MECHANICA, ISSN: 0001-5970, DOI: 10.1007/s00707-022-03417-x, Vol.234, pp.693-704 , 2023

Abstract:
The size-dependent buckling problem of cracked micro- and nanocantilevers, which have many applications as sensors and actuators, is studied by the stress-driven nonlocal theory of elasticity and Bernoulli–Euler beam model. The presence of the crack is modeled by assuming that the sections at the left and right sides of the crack are connected by a rotational spring. The compliance of the spring, which relates the slope discontinuity and the bending moment at the cracked cross section, is related to the crack length using the method of energy consideration and the theory of fracture mechanics. The buckling equations of the left and right sections are solved separately, and the variationally consistent and constitutive boundary and continuity conditions are imposed to close the problem. Novel insightful results are presented about the effects of the crack length and location, and the nonlocality on the critical loads and mode shapes, also for higher modes of buckling. The results of the present model converge to those of the intact nanocantilevers when the crack length goes to zero and to those of the large-scale cracked cantilever beams when the nonlocal parameter vanishes.

Frydrych K., Modelling Irradiation Effects in Metallic Materials Using the Crystal Plasticity Theory—A Review, Crystals, ISSN: 2073-4352, DOI: 10.3390/cryst13050771, Vol.13, No.771, pp.1-20, 2023

Abstract:
The review starts by highlighting the significance of nuclear power plants in the contemporary world, especially its indispensable role in the global efforts to reduce CO2 emissions. Then, it describes the impact of irradiation on the microstructure and mechanical properties of reactor structural materials. The main part provides the reader with a thorough overview of crystal plasticity models developed to address the irradiation effects so far. All three groups of the most important materials are included. Namely, the Zr alloys used for fuel cladding, austenitic stainless steels used for reactor internals, and ferritic steels used for reactor pressure vessels. Other materials, especially those considered for construction of future fission and fusion nuclear power plants, are also mentioned. The review also pays special attention to ion implantation and instrumented nanoindentation which are common ways to substitute costly and time-consuming neutron irradiation campaigns.

Keywords:
irradiation, crystal plasticity, indentation, ion implantation, neutron, metallic materials, nuclear reactor, structural materials

Krajewski M., Kaczmarek A., Tokarczyk M., Lewińska S., Włoczewski M., Bochenek K., Jarząbek D., Mościcki T., Hoffman J., Ślawska-Waniewska A., Laser-Assisted Growth of Fe3O4 Nanoparticle Films on Silicon Substrate in Open Air, physica status solidi (a), ISSN: 1862-6319, DOI: 10.1002/pssa.202200786, No.2200786, pp.1-5, 2023

Abstract:
This work presents a growth of Fe3O4 nanoparticle films on silicon substrate. The iron oxide is deposited applying a pulsed laser deposition technique. The process is performed in open air in the absence and presence of external magnetic field. In fact, the morphologies of the obtained Fe3O4–Si samples are similar. The Fe3O4 nanoparticles are spherical with average diameters of 30 nm and are densely agglomerated on the Si substrate. The Fe3O4–Si material prepared in the absence of magnetic field has revealed more intense signals during X-ray diffraction and Raman measurements. The magnetic investigations indicate that the Fe3O4 nanoparticles are significantly coupled with the Si substrate and do not exhibit superparamagnetic behavior. Moreover, the Verwey transition is 98 K for both investigated Fe3O4–Si samples.

Keywords:
Fe3O4 nanoparticles,magnetic materials,pulsed laser deposition

Jelen Z., Krajewski M., Zupanič F., Majerič P., Švarc T., Anžel I., Ekar J., Liou S., Kubacki J., Tokarczyk M., Rudolf R., Melting point of dried gold nanoparticles prepared with ultrasonic spray pyrolysis and lyophilisation, nanotechnology reviews, ISSN: 2191-9097, DOI: 10.1515/ntrev-2022-0568, Vol.12, No.1, pp.1-12, 2023

Abstract:
A coupled process of ultrasonic spray pyrolysis and lyophilisation was used for the synthesis of dried gold nanoparticles. Two methods were applied for determining their melting temperature: uniaxial microcompression and differential scanning calorimetry (DSC) analysis. Uniaxial microcompression resulted in sintering of the dried gold nanoparticles at room temperature with an activation energy of 26–32.5 J/g, which made it impossible to evaluate their melting point. Using DSC, the melting point of the dried gold nanoparticles was measured to be around 1064.3°C, which is close to pure gold. The reason for the absence of a melting point depression in dried gold nanoparticles was their exothermic sintering between 712 and 908.1°C.

Keywords:
gold nanoparticles, melting point, ultrasonic spray pyrolysis, characterisation

Petryk H.M., On thermodynamic extremal principles in gradient plasticity with energetic forces, Mathematics and Mechanics of Solids, ISSN: 1741-3028, DOI: 10.1177/10812865231196296, pp.1-17, 2023

Abstract:
Incremental energy minimization is revisited as a method of determining an incremental solution for rate-independent dissipative solids undergoing isothermal quasi-static deformation. The incremental minimization is applied to the total internal energy of the compound thermodynamic system that consists of a deforming body with internal variables, a conservative loading device, and an ambient heat reservoir. It is shown that the difference between the virtual and actual dissipation rates plays a fundamental role in this minimization, which is related to thermodynamic extremal principles of local and global type. The analysis is carried out within the gradient plasticity framework with the energetic forces derived as the variational derivative of the Helmholtz free energy depending on the spatial gradient of arbitrary internal variables. Specifications are given for existing models of gradient plasticity.

Keywords:
Dissipation, internal variables, gradient, plasticity, energy, minimization, rate-independent, variational

Deshpande S., Sosa R., Bordas S.P., Lengiewicz J.A., Convolution, aggregation and attention based deep neural networks for accelerating simulations in mechanics, Frontiers in Materials, ISSN: 2296-8016, DOI: 10.3389/fmats.2023.1128954, Vol.10, No.1128954, pp.1-12, 2023

Abstract:
Deep learning surrogate models are being increasingly used in accelerating scientific simulations as a replacement for costly conventional numerical techniques. However, their use remains a significant challenge when dealing with real-world complex examples. In this work, we demonstrate three types of neural network architectures for efficient learning of highly non-linear deformations of solid bodies. The first two architectures are based on the recently proposed CNN U-NET and MAgNET (graph U-NET) frameworks which have shown promising performance for learning on mesh-based data. The third architecture is Perceiver IO, a very recent architecture that belongs to the family of attention-based neural networks–a class that has revolutionised diverse engineering fields and is still unexplored in computational mechanics. We study and compare the performance of all three networks on two benchmark examples, and show their capabilities to accurately predict the non-linear mechanical responses of soft bodies.

Keywords:
surrogate modeling, deep learning-artificial neural network, CNN U-NET, graph U-net, perceiver IO, finite element method

Darban H., Luciano R., Basista M.A., Calibration of the length scale parameter for the stress-driven nonlocal elasticity model from quasi-static and dynamic experiments, MECHANICS OF ADVANCED MATERIALS AND STRUCTURES, ISSN: 1537-6494, DOI: 10.1080/15376494.2022.2077488, Vol.30, No.17, pp. 3518- 3524, 2023

Abstract:
The available experimental results in the literature on the quasi-static bending and free flexural vibration of microcantilevers and nanocantilevers are used to calibrate the length scale parameter of the stress-driven nonlocal elasticity model. The Bernoulli–Euler theory is used to define the kinematic field. The closed form solution derived for the bending problem is used to calibrate the length scale parameter by fitting the load–displacement curves to the experimental results. For the vibration problem, the calibration is done using the least-squares curve fitting method for the natural frequencies. The stress-driven nonlocal theory can adequately capture the size-dependent experimental results.

Keywords:
nonlocal elasticity,stress-driven,experiment,length scale,calibration,MEMS,NEMS

Zakrzewska A., Zargarian S.S., Rinoldi C., Gradys A.D., Jarząbek D.M., Zanoni M., Gualandi C., Lanzi M., Pierini F., Electrospun Poly(vinyl alcohol)-Based Conductive Semi-interpenetrating Polymer Network Fibrous Hydrogel: A Toolbox for Optimal Cross-Linking, ACS Materials Au, ISSN: 2694-2461, DOI: 10.1021/acsmaterialsau.3c00025, Vol.3, No.5, pp.464-482, 2023

Abstract:
Cross-linking of poly(vinyl alcohol) (PVA) creates a three-dimensional network by bonding adjacent polymer chains. The cross-linked structure, upon immersion in water, turns into a hydrogel, which exhibits unique absorption properties due to the presence of hydrophilic groups within the PVA polymer chains and, simultaneously, ceases to be soluble in water. The properties of PVA can be adjusted by chemical modification or blending with other substances, such as polymers, e.g., conductive poly[3-(potassium-5-butanoate)thiophene-2,5-diyl] (P3KBT). In this work, PVA-based conductive semi-interpenetrating polymer networks (semi-IPNs) are successfully fabricated. The systems are obtained as a result of electrospinning of PVA/P3KBT precursor solutions with different polymer concentrations and then cross-linking using “green”, environmentally safe methods. One approach consists of thermal treatment (H), while the second approach combines stabilization with ethanol and heating (E). The comprehensive characterization allows to evaluate the correlation between the cross-linking methods and properties of nanofibrous hydrogels. While both methods are successful, the cross-linking density is higher in the thermally cross-linked samples, resulting in lower conductivity and swelling ratio compared to the E-treated samples. Moreover, the H-cross-linked systems have better mechanical properties─lower stiffness and greater tensile strength. All the tested systems are biocompatible, and interestingly, due to the presence of P3KBT, they show photoresponsivity to solar radiation generated by the simulator. The results indicate that both methods of PVA cross-linking are highly effective and can be applied to a specific system depending on the target, e.g., biomedical or electronic applications.

Keywords:
poly(vinyl alcohol),poly[3-(potassium-5-butanoate)thiophene-2.5-diyl],electrospun nanofibers,cross-linking,fibrous hydrogel,semi-IPN