Polymers

Research

20 pages, 2892 KiB

Open AccessArticle

Untapped Potential of Recycled Thermoplastic Blends in UD Composites via Finite Element Analysis

by Pei Hao, Ninghan Tang, Juan Miguel Tiscar and Francisco A. Gilabert

Polymers 2025, 17(9), 1168; https://doi.org/10.3390/polym17091168 - 25 Apr 2025

Viewed by 154

The increasing demand for fully recyclable composites has spurred extensive research on thermoplastics, valued for their recyclability and excellent mechanical properties. High-performance thermoplastics such as PEEK and PPS have been widely adopted in aerospace applications due to their outstanding load-bearing capabilities, which are [...] Read more.

The increasing demand for fully recyclable composites has spurred extensive research on thermoplastics, valued for their recyclability and excellent mechanical properties. High-performance thermoplastics such as PEEK and PPS have been widely adopted in aerospace applications due to their outstanding load-bearing capabilities, which are well documented. Recently, thermoplastic polymer blends have gained attention for their enhanced recyclability and sustainability, as well as their ability to improve thermal stability, viscosity, and manufacturability. However, limited data are available on the mechanical characterization of composites that incorporate these blends, particularly when recycled thermoplastics are used. In this study, we first examine the stress–strain behavior of the following three polymer blends relevant for structural applications: PES/PEEK, PPS/PEEK, and HDPE/PP. We then perform a numerical analysis to predict the mechanical performance of unidirectional fiber-reinforced composites using each blend as the matrix. This involves a micromechanical Representative Volume Element (RVE) approach combined with an advanced polymer model previously validated against experimental data. The findings are discussed to critically assess the suitability of these blends for producing fully matrix-recycled composites. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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21 pages, 15989 KiB

Open AccessArticle

Deformation Characterization of Glass Fiber and Carbon Fiber-Reinforced 3D Printing Filaments Using Digital Image Correlation

by Vivien Nemes, Szabolcs Szalai, Brigitta Fruzsina Szívós, Mykola Sysyn, Dmytro Kurhan and Szabolcs Fischer

Polymers 2025, 17(7), 934; https://doi.org/10.3390/polym17070934 - 29 Mar 2025

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Abstract

The paper offers an in-depth deformation study of glass fiber-reinforced and carbon composite filaments of 3D printers. During the certification, the authors used DIC (Digital Image Correlation) as a full-field strain measurement technique to explore key material traits as a non-contact optical measurement [...] Read more.

The paper offers an in-depth deformation study of glass fiber-reinforced and carbon composite filaments of 3D printers. During the certification, the authors used DIC (Digital Image Correlation) as a full-field strain measurement technique to explore key material traits as a non-contact optical measurement method. The insights captured through the DIC technology enabled to better understand the localized strain distributions during the loading of these reinforced filaments. The paper analyzes the glass fiber and carbon fiber filaments used in 3D printing that are reinforced with these materials and are subjected to bending and compressive loading. The segment presents how loading affects the performance of reinforced filaments when varying such factors as the deposition patterns, layer orientation, and other process parameters. Different types and combinations of reinforcements and printing variables were tested, and the resulting dependencies of mechanical parameters and failure modes were established for each case. Key conclusions demonstrate that the mechanical behavior of both carbon- and glass fiber-reinforced filaments is strongly affected by the 3D printing parameters, particularly infill density, pattern, and build orientation. The application of Digital Image Correlation (DIC) allowed for a precise, full-field analysis of strain distribution and deformation behavior, offering new insights into the structural performance of fiber-reinforced 3D printed composites. The findings from the study provide guidance for the proper choice of filling material and the optimal parameters for the 3D printing process of models with high-performance indexes and seamless applications in the automotive and industrial manufacturing sectors. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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14 pages, 20648 KiB

Open AccessArticle

Microcanonical Analysis of Semiflexible Homopolymers with Variable-Width Bending Potential

by Matthew J. Williams and Michael C. Gray

Polymers 2025, 17(7), 906; https://doi.org/10.3390/polym17070906 - 27 Mar 2025

Viewed by 251

Abstract

Understanding the structural dynamics of semiflexible polymers in an implicit solvent under varying conditions provides valuable insights into their behavior in diverse environments. In this work, we systematically investigate the effect of the angular width of the bending potential on structural state behavior [...] Read more.

Understanding the structural dynamics of semiflexible polymers in an implicit solvent under varying conditions provides valuable insights into their behavior in diverse environments. In this work, we systematically investigate the effect of the angular width of the bending potential on structural state behavior and conformational variability using microcanonical analysis. A range of angular widths is explored, with the widest value corresponding directly to the classic semiflexible polymer model, which exhibits a diverse set of structural states, including Two-Strand, Three-Strand, Four-Strand, Ring, Random Coil, and Globule configurations. As the angular width narrows, structural variability within states decreases, overlap between structural states is reduced, and conformations become more stable, leading to an expansion of the parameter space dominated by individual structures. By examining microcanonical entropy and its derivatives, we identify transitions analogous to first-, second-, and third-order thermodynamic transitions, providing a deeper understanding of the configurational landscape of semiflexible polymers. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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19 pages, 5025 KiB

Open AccessArticle

Investigations on Thermal Transitions in PDPP4T/PCPDTBT/AuNPs Composite Films Using Variable Temperature Ellipsometry

by Paweł Jarka, Barbara Hajduk, Pallavi Kumari, Henryk Janeczek, Marcin Godzierz, Yao Mawuena Tsekpo and Tomasz Tański

Polymers 2025, 17(5), 704; https://doi.org/10.3390/polym17050704 - 6 Mar 2025

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Abstract

Herein, we report a comprehensive investigation on the thermal transitions of thin films of poly [2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione -3,6-diyl)-alt-(2,2′;5′,2″;5″,2′″-quaterthiophen-5,5′″-diyl)]PDPP4T, poly[2,6-(4,4-bis-(2-ethy-lhexyl)-4H-cyclopenta [2,1-b;3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] PCPDTBT, 1:1 blend of PDPP4T and PCPDTBT, and their composites with gold nanoparticles (AuNPs). The thermal transitions of these materials were studied using variable [...] Read more.

Herein, we report a comprehensive investigation on the thermal transitions of thin films of poly [2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione -3,6-diyl)-alt-(2,2′;5′,2″;5″,2′″-quaterthiophen-5,5′″-diyl)]PDPP4T, poly[2,6-(4,4-bis-(2-ethy-lhexyl)-4H-cyclopenta [2,1-b;3,4-b′]dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] PCPDTBT, 1:1 blend of PDPP4T and PCPDTBT, and their composites with gold nanoparticles (AuNPs). The thermal transitions of these materials were studied using variable temperature spectroscopic ellipsometry (VTSE), with differential scanning calorimetry (DSC) serving as the reference method. Based on obtained VTSE results, for the first time, we have determined the phase diagrams of PDPP4T/PCPDTBT and their AuNPs composites. The VTSE measurements revealed distinct thermal transitions in the thin films, including characteristic temperatures corresponding to the pure phases of PDPP4T and PCPDTBT within their blends. These transitions were markedly different in the AuNPs composites compared to the neat materials, highlighting the unique interactions between the polymer matrix and AuNPs. Additionally, we explored the optical properties, surface morphology, and crystallinity of the materials. We hypothesize that the observed variations in thermal transitions, as well as the improvement in optical properties and crystallinity, are likely influenced by localized surface plasmon resonance (LSPR) and passivation phenomena induced by the AuNPs in the composite films. These findings could have important implications for the design and optimization of materials for optoelectronic applications. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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18 pages, 13148 KiB

Open AccessArticle

Enhancing Radiation Shielding Efficiency of Nigella sativa Eumelanin Polymer Through Heavy Metals Doping

by Mohammad Marashdeh and Nawal Madkhali

Polymers 2025, 17(5), 609; https://doi.org/10.3390/polym17050609 - 25 Feb 2025

Viewed by 461

Abstract

Gamma radiation shielding is necessary for many applications; nevertheless, lead creates environmental risks. Eumelanin, a natural polymer, is a viable alternative, although its effectiveness is limited to lower gamma-ray energy. This research looks at how doping the herbal eumelanin polymer (Nigella sativa [...] Read more.

Gamma radiation shielding is necessary for many applications; nevertheless, lead creates environmental risks. Eumelanin, a natural polymer, is a viable alternative, although its effectiveness is limited to lower gamma-ray energy. This research looks at how doping the herbal eumelanin polymer (Nigella sativa) with heavy metals including iron (Fe), copper (Cu), and zinc (Zn) affects its gamma radiation shielding characteristics. The inclusion of these metals considerably increases the linear attenuation coefficient (μ) and mass attenuation coefficient (μ_m) of eumelanin, especially at lower photon energies where the photoelectric effect is prominent. The μ value of pure eumelanin is 0.193 cm⁻¹ at 59.5 keV. It goes up to 0.309 cm⁻¹, 0.420 cm⁻¹, and 0.393 cm⁻¹ when Fe, Cu, and Zn are added, in that order. Similarly, the mass attenuation coefficients increase from 0.153 cm²/g for pure eumelanin to 0.230, 0.316, and 0.302 cm²/g for the Fe-, Cu-, and Zn-doped samples. At intermediate and higher energies (661.7 keV-to-1332.5 keV), where Compton scattering is the main interaction, differences in attenuation coefficients between samples are not as noticeable, which means that metal additions have less of an effect. The mean free path (MFP) and radiation protection efficiency (RPE) also show these behaviors. For example, at 59.5 keV the MFP drops from 5.172 cm for pure eumelanin to 3.244 cm for Mel-Fe, 2.385 cm for Mel-Cu, and 2.540 cm for Mel-Zn. RPE values also go up a lot at low energies. For example, at 59.5 keV Cu-doped eumelanin has the highest RPE of 34.251%, while pure eumelanin only has an RPE of 17.581%. However, at higher energies the RPE values for all samples converge, suggesting a more consistent performance. These findings suggest that doping eumelanin with Fe, Cu, and Zn is particularly effective for enhancing gamma-ray shielding at low energies, with copper (Cu) providing the most significant improvement overall, making these composites suitable for applications requiring enhanced radiation protection at lower gamma-ray energies. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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25 pages, 7471 KiB

Open AccessArticle

Multiscale Numerical Study of Enhanced Ductility Ratios and Capacity in Carbon Fiber-Reinforced Polymer Concrete Beams for Safety Design

by Moab Maidi, Gili Lifshitz Sherzer and Erez Gal

Polymers 2025, 17(2), 234; https://doi.org/10.3390/polym17020234 - 17 Jan 2025

Cited by 1 | Viewed by 675

Abstract

Rigid reinforced concrete (RC) frames are generally adopted as stiff elements to make the building structures resistant to seismic forces. However, a method has yet to be fully sought to provide earthquake resistance through optimizing beam and column performance in a rigid frame. [...] Read more.

Rigid reinforced concrete (RC) frames are generally adopted as stiff elements to make the building structures resistant to seismic forces. However, a method has yet to be fully sought to provide earthquake resistance through optimizing beam and column performance in a rigid frame. Due to its high corrosion resistance, the integration of CFRP offers an opportunity to reduce frequent repairs and increase durability. This paper presents the structural response of CFRP beams integrated into rigid frames when subjected to seismic events. Without any design provision for CFRP systems in extreme events, multiscale simulations and parametric analyses were performed to optimize the residual state and global performance. Macroparameters, represented by the ductility ratio and microfactors, have been analyzed using a customized version of the modified compression field theory (MCFT). The main parameters considered were reinforcement under tension and compression, strength of concrete, height-to-width ratio, section cover, and confinement level, all of which are important to understand their influence on seismic performance. The parametric analysis results highlight the increased ductility and higher load-carrying capacity of the CFRP-reinforced tested component compared to the RC component. These results shed light on the possibility of designing CFRP-reinforced concrete components that could improve ductile frames with increased energy dissipation and be suitable for applications in non-corrosive seismic-resistant buildings. This also shows reduced brittleness and enhancement in the failure mode. Numerical simulations and experimental results showed a strong correlation with a deviation of about 8.3%, underlining the reliability of the proposed approach for designing seismic-resistant CFRP-reinforced structures. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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17 pages, 3242 KiB

Open AccessArticle

A Multi-Phase Analytical Model for Effective Electrical Conductivity of Polymer Matrix Composites Containing Micro-SiC Whiskers and Nano-Carbon Black Hybrids

by Usama Umer, Mustufa Haider Abidi, Zeyad Almutairi and Mohamed K. Aboudaif

Polymers 2025, 17(2), 128; https://doi.org/10.3390/polym17020128 - 7 Jan 2025

Viewed by 759

Abstract

Multifunctional polymer composites containing micro/nano hybrid reinforcements have attracted intensive attention in the field of materials science and engineering. This paper develops a multi-phase analytical model for investigating the effective electrical conductivity of micro-silicon carbide (SiC) whisker/nano-carbon black (CB) polymer composites. First, CB [...] Read more.

Multifunctional polymer composites containing micro/nano hybrid reinforcements have attracted intensive attention in the field of materials science and engineering. This paper develops a multi-phase analytical model for investigating the effective electrical conductivity of micro-silicon carbide (SiC) whisker/nano-carbon black (CB) polymer composites. First, CB nanoparticles are dispersed within the non-conducting epoxy to achieve a conductive CB-filled nanocomposite and its electrical conductivity is predicted. Some critical microstructures such as volume percentage and size of nanoparticles, and interphase characteristics surrounding the CB are micromechanically captured. Next, the electrical conductivity of randomly oriented SiC-containing composites in which the nanocomposite and whisker are considered as the matrix and reinforcement phases, respectively, is estimated. Influences of whisker aspect ratio and volume fraction on the effective electrical conductivity of the SiC/CB-containing polymer composites are explored. Some comparison studies are performed to validate the accuracy of the model. It is observed before the percolation threshold that the addition of nanoparticles with a uniform dispersion can improve the electrical conductivity of the polymer composites containing SiC/CB hybrids. Moreover, the results show that the electrical conductivity is more enhanced by the decrease in nanoparticle size. Interestingly, the composite percolation threshold is significantly reduced when SiC whiskers with a higher aspect ratio are added. This work will be favorable for the design of electro-conductive polymer composites with high performances. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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19 pages, 3611 KiB

Open AccessArticle

Effects of Silica Nanoparticles on the Piezoelectro-Elastic Response of PZT-7A–Polyimide Nanocomposites: Micromechanics Modeling Technique

by Usama Umer, Mustufa Haider Abidi, Syed Hammad Mian, Fahad Alasim and Mohammed K. Aboudaif

Polymers 2024, 16(20), 2860; https://doi.org/10.3390/polym16202860 - 10 Oct 2024

Viewed by 1045

Abstract

By using piezoelectric materials, it is possible to convert clean and renewable energy sources into electrical energy. In this paper, the effect on the piezoelectro-elastic response of piezoelectric-fiber-reinforced nanocomposites by adding silica nanoparticles into the polyimide matrix is investigated by a micromechanical method. [...] Read more.

By using piezoelectric materials, it is possible to convert clean and renewable energy sources into electrical energy. In this paper, the effect on the piezoelectro-elastic response of piezoelectric-fiber-reinforced nanocomposites by adding silica nanoparticles into the polyimide matrix is investigated by a micromechanical method. First, the Ji and Mori–Tanaka models are used to calculate the properties of the nanoscale silica-filled polymer. The nanoparticle agglomeration and silica–polymer interphase are considered in the micromechanical modeling. Then, considering the filled polymer as the matrix and the piezoelectric fiber as the reinforcement, the Mori–Tanaka model is used to estimate the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites. It was found that adding silica nanoparticles into the polymer improves the elastic and piezoelectric properties of the piezoelectric fibrous nanocomposites. When the fiber volume fraction is 60%, the nanocomposite with the 3% silica-filled polyimide exhibits 39%, 31.8%, and 37% improvements in the transverse Young’s modulus

E_{T}

, transverse shear modulus

G_{T L}

, and piezoelectric coefficient

e_{31}

in comparison with the composite without nanoparticles. Furthermore, the piezoelectro-elastic properties such as

E_{T}

,

G_{T L}

, and

e_{31}

can be improved as the nanoparticle diameter decreases. However, the elastic and piezoelectric constants of the piezoelectric fibrous nanocomposites decrease once the nanoparticles are agglomerated in the polymer matrix. A thick interphase with a high stiffness enhances the nanocomposite’s piezoelectro-elastic performance. Also, the influence of volume fractions of the silica nanoparticles and piezoelectric fibers on the nanocomposite properties is studied. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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