Polymers

Research

Jump to: Review

23 pages, 25347 KB

Open AccessArticle

Synergistic Reinforcement of Polyvinyl Alcohol Nanocomposites by Calcined Eggshell and Carbon Nanotubes

by Soo-Tueen Bee, Lee Tin Sin and Sin-Yee Yeoh

Polymers 2026, 18(9), 1033; https://doi.org/10.3390/polym18091033 - 24 Apr 2026

Viewed by 600

Abstract

This study investigated the impact of incorporating calcined eggshell and carbon nanotube (CNT) on the properties of polyvinyl alcohol (PVOH) blends. Prior to solution casting, eggshell waste underwent a calcination process and then the samples were prepared via solution cast method. Mechanical properties [...] Read more.

This study investigated the impact of incorporating calcined eggshell and carbon nanotube (CNT) on the properties of polyvinyl alcohol (PVOH) blends. Prior to solution casting, eggshell waste underwent a calcination process and then the samples were prepared via solution cast method. Mechanical properties study revealed a significant enhancement in tensile strength and elongation at break with increasing loads of calcined eggshell and CNT. Higher tensile strength was observed with increasing CNT loading for PVOH blends added with 1 phr and 3 phr calcined eggshell, owing to the reinforcing role of CNT in the composite matrix. In contrast, the tensile strength at 0.3 phr CNT is lower than at 0.2 phr CNT due to CNT agglomeration, which weakens the interfacial adhesion with the PVOH matrix and hinders effective stress transfer during deformation. SEM images depicted well-dispersion and interaction effect of calcined eggshell particles and CNT particles at low loading levels. The good interaction effect between calcined eggshell and PVOH matrix (which both exhibit hydrophilic behaviour) is mainly attributed to the presence of hydrogen bonding in the polymer matrix, as proven in FTIR analysis. XRD analysis revealed significant peaks in the 2θ range of 19° to 21°, suggesting that increased amounts of calcined eggshells influenced the crystallite size of the original PVOH matrix. In summary, the addition of calcined eggshell and CNT at low loading levels markedly enhanced the mechanical, physical, and thermal properties of the composite material. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

38 pages, 12925 KB

Open AccessArticle

Effect of the Hole Diameter Ratio (d/H) on the Web Crippling Capacity of Pultruded GFRP U-Channels Under Temperature and Loading Conditions

by Mohamed Ahmed Soumbourou, Emrah Madenci, Ceyhun Aksoylu and Yasin Onuralp Özkılıç

Polymers 2026, 18(8), 1002; https://doi.org/10.3390/polym18081002 - 21 Apr 2026

Viewed by 541

Abstract

Glass fiber reinforced polymer (GFRP) composites produced by pultrusion are increasingly used in structural applications due to their advantages such as corrosion resistance, high strength-to-weight ratio, and lightness. However, the extensive use of fibers in the longitudinal direction causes imbalance in the cross-section, [...] Read more.

Glass fiber reinforced polymer (GFRP) composites produced by pultrusion are increasingly used in structural applications due to their advantages such as corrosion resistance, high strength-to-weight ratio, and lightness. However, the extensive use of fibers in the longitudinal direction causes imbalance in the cross-section, leading to web crippling behavior in profiles subjected to transverse vertical forces. In this study, the influence of temperature and hole diameter on the web crippling performance of pultruded GFRP U-section profiles was investigated experimentally and analytically. The specimens were perforated with circular holes with diameters of 32–50–70 mm (diameter/Height ratio d/H = 0.23–0.36–0.50) at the web center and exposed to high temperatures of 200–250–300 °C, respectively, along with room temperature. The experiments were conducted under ITF (interior-two-flange) and ETF (end-two-flange) loading conditions. According to the results obtained, ITF configurations exhibited approximately twice the load-carrying capacity compared to ETF configurations. Due to the effect of high temperature, the web–crushing capacity showed a significant decrease of up to 44% on average in all samples when the temperature was increased from 24 °C to 300 °C. Increasing the hole diameter (and consequently the d/H ratio) led to a gradual decrease in capacity ranging from 15.7% to 56.2%; in particular, it was demonstrated that the ETF loading configuration is more sensitive to the hole than the ITF. As a result of the study, an empirical equation considering the effects of temperature and hole size was proposed, and the model’s predictions were compared with experimental results. Although the model successfully captured the general trend, the average absolute error rate in the predictions ranged between 12% and 14%, indicating improvement but not achieving ideal prediction accuracy. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

16 pages, 1563 KB

Open AccessArticle

Innovative Thermoplastics Composites Made from Recycled Poly(Propylene) Reinforced with Coconut Coir Fibers

by Arif Nuryawan, Nanang Masruchin, Raja Biandi Damanik, Iwan Risnasari, Hardiansyah Tambunan, Himsar Ambarita and Byung-Dae Park

Polymers 2026, 18(4), 432; https://doi.org/10.3390/polym18040432 - 9 Feb 2026

Viewed by 851

Abstract

This study aims to evaluate the properties of poly(propylene) or PP composite reinforced with coconut coir fibers, and how these vary with fiber length and composition ratio. This innovative thermoplastic composite material was manufactured using a low-tech process from only PP, coconut coir [...] Read more.

This study aims to evaluate the properties of poly(propylene) or PP composite reinforced with coconut coir fibers, and how these vary with fiber length and composition ratio. This innovative thermoplastic composite material was manufactured using a low-tech process from only PP, coconut coir fibers, and xylene (dissolution agent). Therefore, this process is widely accessible whilst both reusing/recycling waste plastic and making use of waste fiber material to produce a useful material that can fulfill demand for wood products, which has many environmental benefits. In this research, the coconut coir fibers are used as reinforcement, as well as the filler of the composite. Nine variations in composite material were produced from three length categories of fibers (2–5 mm, 10–20 mm, and 30–40 mm) and three composition ratios (60:40, 70:30, and 80:20) of predominant plastics of PP and fibers. Physical properties of the respective composite, such as density, moisture content, and thickness swelling, were fulfilled to the Japanese Industrial Standard (JIS) for particleboard. Mechanical properties of the composites showed that both modulus of elasticity (MoE) and modulus of rupture (MoR) decreased as the length of the fibers used increased. Conversely, an increase in the proportion of PP resulted in a stronger composite. However, statistically, the interaction between the amount of PP and the length of coir fibers within the biocomposite did not influence their quality. These results demonstrate that a low-cost process for manufacturing composite from waste materials can meet most industry standards and indicate that further refinement of the process, building on these findings, could achieve an innovative thermoplastic composite with widespread structural applications whilst delivering environmental benefits. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Graphical abstract

15 pages, 3038 KB

Open AccessArticle

Enhancing Interfacial and Mechanical Properties of Carbon Fiber/Poly (Ether Ether Ketone) Composites via Bisphenol-Based Polyimide Modification

by Aylin Albayrak, Mustafa Dogu, Mustafa Cakir and Kadir Turhan

Polymers 2025, 17(24), 3258; https://doi.org/10.3390/polym17243258 - 7 Dec 2025

Cited by 1 | Viewed by 1044

Abstract

This study focuses on the synthesis of two new bisphenol-based polyimide (PI) sizing agents to improve the fiber–matrix interface of carbon fiber-reinforced poly (ether ether ketone) (CF/PEEK) composites. One of the synthesized polyimides contains bisphenol A (BPA) monomer, while the other has bisphenol [...] Read more.

This study focuses on the synthesis of two new bisphenol-based polyimide (PI) sizing agents to improve the fiber–matrix interface of carbon fiber-reinforced poly (ether ether ketone) (CF/PEEK) composites. One of the synthesized polyimides contains bisphenol A (BPA) monomer, while the other has bisphenol S (BPS) monomer. The produced polyimide precursor resins were coated with carbon fibers by thermal imidization. The thermal, thermomechanical, and mechanical properties of the CF/PEEK composites produced by the autoclave process were investigated. According to the mechanical test results, there was a balanced performance between the BPS-containing polyimide-coated composites (CF-PEEK-PI-S) and the BPA-containing polyimide-coated composites (CF-PEEK-PI-A). While tensile strength is 291 MPa and interlaminar shear (ILSS) strength is 119 MPa, the CF-PEEK-PI-A sample showed superior mechanical properties in flexural (92.1 MPa) and compressive strength (54.9 MPa). As a result, it was concluded that bisphenol-based polyimide coatings significantly improve the interfacial interactions in CF/PEEK composites, which have great potential in aerospace, automotive and advanced engineering applications. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Graphical abstract

17 pages, 10712 KB

Open AccessArticle

An Euler Graph-Based Path Planning Method for Additive Manufacturing Thin-Walled Cellular Structures of Continuous Fiber-Reinforced Thermoplastic Composites

by Guocheng Liu, Fei Wang, Qiyong Tu, Ning Hu, Zhen Ouyang, Wenting Wei, Lei Yang and Chunze Yan

Polymers 2025, 17(23), 3236; https://doi.org/10.3390/polym17233236 - 4 Dec 2025

Cited by 1 | Viewed by 1266

Abstract

Thin-walled cellular structures of continuous fiber-reinforced thermoplastic composites (CFRTPCs) have received much attention from both academics and industry due to their superior properties. Additive manufacturing provides an efficient solution for fabricating these thin-walled cellular structures of CFRTPCs. However, the process often requires cutting [...] Read more.

Thin-walled cellular structures of continuous fiber-reinforced thermoplastic composites (CFRTPCs) have received much attention from both academics and industry due to their superior properties. Additive manufacturing provides an efficient solution for fabricating these thin-walled cellular structures of CFRTPCs. However, the process often requires cutting fiber filaments at jumping points during printing. Furthermore, the filament may twist, fold, and break due to sharp turns in the printing path. These issues adversely affect the mechanical properties of the additive manufactured part. In this paper, a Euler graph-based path planning method for additive manufacturing of CFRTPCs is proposed to avoid jumping and sharp turns. Euler graphs are constructed from non-Eulerian graphs using the method of doubled edges. An optimized Hierholzer’s algorithm with pseudo-intersections is proposed to generate printing paths that satisfy the continuity, non-crossing, and avoid most of the sharp turns. The average turning angle was reduced by up to

20.88 %

and the number of turning angles less than or equal to

120 °

increased by up to

26.67 %

using optimized Hierholzer’s algorithm. In addition, the generated paths were verified by house-made robot-assisted additive manufacturing equipment. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Graphical abstract

16 pages, 5272 KB

Open AccessArticle

Mechanical and Adhesive Properties of Hydrothermally Treated Bamboo Composites Reinforced with Phenolic Resin: Effect of Impregnation with Silica Nanoparticles

by Lionnel Frederique Bidzanga Bessala and Yanjun Li

Polymers 2025, 17(22), 2989; https://doi.org/10.3390/polym17222989 - 11 Nov 2025

Cited by 1 | Viewed by 975

Abstract

This study investigates the synergistic effect of phenolic resin impregnation on the mechanical and adhesive properties of hydrothermally treated bamboo composites further reinforced with a silica nanoparticle sol–gel catalyzed by Fe₃O₄ (SiO₂/Fe₃O₄). The hydrothermal [...] Read more.

This study investigates the synergistic effect of phenolic resin impregnation on the mechanical and adhesive properties of hydrothermally treated bamboo composites further reinforced with a silica nanoparticle sol–gel catalyzed by Fe₃O₄ (SiO₂/Fe₃O₄). The hydrothermal pre-treatment was found to enhance cellulose crystallinity, as confirmed through XRD analysis. Dynamic mechanical analysis (DMA) and nanoindentation tests revealed that the hybrid treatment significantly influences the viscoelastic response. Composites treated only with hot water and resin (GB-W) exhibited superior short-term creep resistance and higher elasticity, attributed to their optimized crystalline structure. In contrast, the silica-reinforced composites (GB-M) demonstrated the most viscous behavior and lowest stress relaxation, making them most effective at minimizing elastic springback. Nanoindentation further showed that GB-W had the highest nano-adherence at the fiber cell wall level. FTIR analysis indicated a stronger interaction between the phenolic resin and the hydroxyl groups of the bamboo matrix in GB-0 and GB-W compared to GB-M, where the silica layer potentially altered this interface. Microscopy confirmed a resin penetration depth of at least 1 mm, primarily into porous tissues. The results demonstrate that while silica reinforcement enhances relaxation properties, the hydrothermal pre-treatment combined with phenolic resin creates a more favorable interface, leading to better overall creep resistance and adherence. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

21 pages, 64275 KB

Open AccessArticle

Characterization on Mode-I/II Interlaminar Strength and Fracture Toughness of Co-Cured Fiber–Metal Laminates

by Mingjie Wang, Hongyi Hao, Qinghao Liu, Xinyue Miao, Ziye Lai, Tianqi Yuan, Guohua Zhu and Zhen Wang

Polymers 2025, 17(21), 2937; https://doi.org/10.3390/polym17212937 - 2 Nov 2025

Cited by 2 | Viewed by 1783

Abstract

This study systematically evaluates the mode-I (opening) and mode-II (shearing) interlaminar strength and fracture toughness of four co-cured fiber–metal laminates (FMLs): AL–CF (aluminum–carbon fiber fabric), AL–GF (aluminum–glass fiber fabric), AL–HC (aluminum–carbon/glass hybrid fabric), and AL–HG (aluminum–glass/carbon hybrid fabric). Epoxy adhesive films were interleaved [...] Read more.

This study systematically evaluates the mode-I (opening) and mode-II (shearing) interlaminar strength and fracture toughness of four co-cured fiber–metal laminates (FMLs): AL–CF (aluminum–carbon fiber fabric), AL–GF (aluminum–glass fiber fabric), AL–HC (aluminum–carbon/glass hybrid fabric), and AL–HG (aluminum–glass/carbon hybrid fabric). Epoxy adhesive films were interleaved between metal and composite plies to enhance interfacial bonding. Mode-I interlaminar tensile strength (ILTS) and mode-II interlaminar shear strength (ILSS) were measured using curved beam and short beam tests, respectively, while mode-I and mode-II fracture toughness (

G_{I c}

and

G_{I I c}

) were obtained from double cantilever beam (DCB) and end-notched flexure (ENF) tests. Across laminates, interlaminar tensile strength (ILTS) values lie in a narrow band of 31.6–31.8 MPa and interlaminar shear strength (ILSS) values in 41.0–41.9 MPa. The mode-I initiation (

G_{I c, i n i t}

) and propagation (

G_{I c, p r o p}

) toughnesses are 0.44–0.56 kJ/m² and 0.54–0.64 kJ/m², respectively, and the mode-II toughness (

G_{I I c}

) is 0.65–0.79 kJ/m². Scanning electron microscopy reveals that interlaminar failure localizes predominantly at the metal–adhesive interface, displaying river-line features under mode-I and hackle patterns under mode-II, whereas the adhesive–composite interface remains intact. Collectively, the results indicate that, under the present processing and test conditions, interlaminar strength and toughness are governed by the metal–adhesive interface rather than the composite reinforcement type, providing a consistent strength–toughness baseline for model calibration and interfacial design. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

23 pages, 3081 KB

Open AccessArticle

Crashworthiness Prediction of Perforated Foam-Filled CFRP Rectangular Tubes Crash Box Using Machine Learning

by Harri Junaedi, Khaled Akkad, Tabrej Khan, Marwa A. Abd El-baky, Mahmoud M. Awd Allah and Tamer A. Sebaey

Polymers 2025, 17(21), 2887; https://doi.org/10.3390/polym17212887 - 29 Oct 2025

Viewed by 1405

Abstract

The use of carbon fiber-reinforced polymer (CFRP) tubes as crash boxes has become a subject of interest due to their high specific strength and energy absorption capabilities. This study investigates the crashworthiness performance of rectangular tubes made of CFRP, with and without holes [...] Read more.

The use of carbon fiber-reinforced polymer (CFRP) tubes as crash boxes has become a subject of interest due to their high specific strength and energy absorption capabilities. This study investigates the crashworthiness performance of rectangular tubes made of CFRP, with and without holes and polyurethane foam (PUF)-filled inner structures. The designed tubes were subjected to quasi-static axial compression loading. In addition to carefully documenting failure histories, data on crash load and displacement responses were methodically recorded during testing. To evaluate crashworthiness performance, three design parameters were considered: hole diameter, the number of holes in both the x and y directions, and whether the tube was filled with foam or left unfilled. Machine learning (ML) was also used to reduce the time and cost by predicting the crashworthiness indicators of the tubes from fewer experiments. A collection of ML algorithms such as decision tree regressor (DTR), linear regressor (LR), ridge regressor (RR), lasso regressor (LAR), elastic nets (ENs), and multi-layer perceptron (MLP) have been utilized to predict crashworthiness indicators such as initial peak force (P_ip), mean crushing force (P_m) and energy absorption (EA) of the design tubes from the experimental data. The experimental results showed that PUF-filling significantly enhanced crashworthiness properties, with P_m and EA increasing by nearly threefold compared to unfilled tubes. Furthermore, in unfilled tubes, the introduction of holes led to varying effects depending on the hole diameter and placement. Meanwhile, in PUF-filled tubes, the presence of holes reduced the crashworthiness performance. For ML prediction, the DTR achieved the best accuracy with the lowest value of root mean squared error (RMSE) and mean absolute percentage error (MAPE) of 1251 and 11.37%, respectively. These findings demonstrate both the importance of PUF-filled, perforation configurations and the feasibility of ML models in optimizing CFRP crash box designs. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

27 pages, 11573 KB

Open AccessArticle

Development of Polymer–Gel Fibrous Composites for Well Water Shutoff in Fractured–Porous Carbonate Formations

by Aleksey Telin, Ravil Yakubov, Artem Pavlik, Vladimir Dokichev, Rida Gallyamova, Anton Mamykin, Farit Safarov, Vladimir Strizhnev, Sergey Vezhnin, Anatoly Politov and Lyubov Lenchenkova

Polymers 2025, 17(11), 1541; https://doi.org/10.3390/polym17111541 - 1 Jun 2025

Cited by 4 | Viewed by 2101

Abstract

The challenge of water shutoff in carbonate reservoirs is complicated by the presence of fractures, which cannot be effectively blocked using conventional hydrogel screens designed for granular reservoirs. To reliably seal fractures, fibrous and dispersed fillers are added to hydrogels. These fillers must [...] Read more.

The challenge of water shutoff in carbonate reservoirs is complicated by the presence of fractures, which cannot be effectively blocked using conventional hydrogel screens designed for granular reservoirs. To reliably seal fractures, fibrous and dispersed fillers are added to hydrogels. These fillers must exhibit affinity for the matrix to ensure the composites can effectively isolate water. Given the wide variability in fracture apertures, it is evident that water shutoff composites should incorporate fibers and dispersed fillers of varying geometric sizes. This study presents a range of hydrogel composites reinforced with mono-, bi-, and tri-component fibers, as well as dispersed fillers, designed for water shutoff in fractured carbonate reservoirs with varying fracture apertures. Oscillation test results demonstrated a twofold increase in the elastic modulus (40–45 Pa) for compositions with various fillers compared to the base composition (23 Pa). Filtration studies revealed the effectiveness of the optimized compositions under different fracture apertures. Specifically, even at a fracture aperture of 650 μm, the residual resistance factor (RRF) reached 82.3 and 9.76 at water flow rates of 0.1 cm³/min and 0.5 cm³/min, respectively. The conducted rheological and filtration tests, along with field trials, confirmed the validity of the selected approach. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

21 pages, 7002 KB

Open AccessArticle

The Effect of Nano-Biochar Derived from Olive Waste on the Thermal and Mechanical Properties of Epoxy Composites

by Muhammed İhsan Özgün, Vildan Erci, Emrah Madenci and Fatih Erci

Polymers 2025, 17(10), 1337; https://doi.org/10.3390/polym17101337 - 14 May 2025

Cited by 6 | Viewed by 1820

Abstract

The increasing demand for the development of environmentally friendly alternatives to petroleum-derived materials has increased research efforts on sustainable polymer composites. This study systematically examined the effect of nano-biochar derived from agricultural wastes such as olive pulp on the mechanical and thermal properties [...] Read more.

The increasing demand for the development of environmentally friendly alternatives to petroleum-derived materials has increased research efforts on sustainable polymer composites. This study systematically examined the effect of nano-biochar derived from agricultural wastes such as olive pulp on the mechanical and thermal properties of epoxy-resin-based composites. First, the biochar from olive pulp was produced by pyrolysis at 450 °C and turned to nano-biochar using ball milling. Composite samples containing nano-biochar at different rates between 0 and 10% were prepared. The nano-biochar and composite samples were characterized by using different techniques such as SEM-EDS, BET, FTIR, XRD, Raman, TGA, and DMA analyses. Also, the tensile strength, elastic modulus, Shore D hardness, thermal stability, and static toughness of the composite samples were evaluated. The best performance was observed in the sample containing 6% nano-biochar; the ultimate tensile strength increased from 17.37 MPa to 23.46 MPa compared to pure epoxy, and the elastic modulus and hardness increased. However, a decrease in brittleness and toughness was observed at higher additive rates. FTIR and DMA analyses indicated that the nano-biochar interacted strongly with the epoxy matrix and increased its thermal stability. The results showed that the olive-pulp-derived nano-biochar could be used to improve the structural and thermal properties of the epoxy composites as an inexpensive and environmentally friendly filler. As a result, this study contributes to the production of new polymer-based materials that will encourage the production of environmentally friendly composites with nano-scale biochar obtained from olive waste, which is an easily accessible, renewable by-product. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

18 pages, 1064 KB

Open AccessArticle

Post-Curing Effects on the Tensile Properties of Hybrid Fiber-Reinforced Polymers: Experimental and Numerical Insights

by Mohammed Zaini, Oumayma Hamlaoui, Jalal Chafiq, Mohamed Ait El Fqih, Mohamed Idiri, Said Aqil, Mohamed Karim Hajji, Alperen Bal, Hakan Tozan, Marta Harnicárová and Jan Valicek

Polymers 2025, 17(9), 1261; https://doi.org/10.3390/polym17091261 - 6 May 2025

Cited by 16 | Viewed by 2771

Abstract

This study investigates the effects of post-curing temperatures on the tensile properties of hybrid basalt-jute-glass-carbon fiber-reinforced polymers (FRPs). Composite specimens were post-cured at 60 °C and 100 °C for 60 min, and their tensile behavior was assessed using a servo-hydraulic testing machine. Numerical [...] Read more.

This study investigates the effects of post-curing temperatures on the tensile properties of hybrid basalt-jute-glass-carbon fiber-reinforced polymers (FRPs). Composite specimens were post-cured at 60 °C and 100 °C for 60 min, and their tensile behavior was assessed using a servo-hydraulic testing machine. Numerical simulations using the Abaqus software V6.14 were also conducted to compare experimental and computational results. The findings indicate that post-curing heat treatment enhances ductility due to increased polymer cross-linking, but excessive heat treatment at 100 °C negatively impacts elongation at fracture. The results revealed that specimens post-cured at 60 °C exhibited the optimal balance between strength and ductility, with increased elongation and moderate tensile strength. However, at 100 °C, while tensile strength improved in some cases, a significant decrease in elasticity and an increased risk of brittleness were observed, suggesting that extreme heat treatment may degrade polymer integrity. Natural fiber composites, particularly jute-based samples, outperformed synthetic composites in terms of elongation and overall mechanical stability. The numerical simulations provided further insights but showed discrepancies with experimental results, mainly due to fiber property variations and fabric waviness, underscoring the challenges of accurately modeling woven composites. The study highlights the importance of controlled post-curing temperatures in optimizing the mechanical performance of FRP composites, with 60 °C identified as the most effective condition for achieving a favorable balance between tensile strength, flexibility, and material durability. These findings offer valuable insights for material scientists and engineers working on the development of high-performance composite materials for structural and industrial applications. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

17 pages, 19395 KB

Open AccessArticle

Effect of Laser Processing Parameters on the Quality of Titanium Alloy Cladding Layer on Carbon Fiber-Reinforced Polymer

by Jiayan Li, Xuan Su, Fenxiang Wang, Donghe Zhang, Yingke Wang, Haoran Song, Jie Xu and Bin Guo

Polymers 2025, 17(9), 1195; https://doi.org/10.3390/polym17091195 - 27 Apr 2025

Cited by 2 | Viewed by 1368

Abstract

To address the insufficient bonding performance between TC4 (Ti-6Al-4V) coating and carbon fiber-reinforced thermoplastic (CFRP) matrices that limits engineering applications of composite structures, TC4 coatings were fabricated on CFRP polymer composites via laser cladding and analyzed using scanning electron microscopy (SEM) and transmission [...] Read more.

To address the insufficient bonding performance between TC4 (Ti-6Al-4V) coating and carbon fiber-reinforced thermoplastic (CFRP) matrices that limits engineering applications of composite structures, TC4 coatings were fabricated on CFRP polymer composites via laser cladding and analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to examine the interface morphology, microstructure, and phase composition. The influence of laser processing parameters on the cladding quality was assessed based on the mechanical performance of the TC4 coating. The findings revealed that insufficient laser power (<230 W) or excessive scanning speed (>1.4 m/min) led to incomplete melting of TC4 powder, preventing the formation of intermetallic compound (IMC) layers. Conversely, excessive laser power (>270 W) or a low scanning speed (<1.0 m/min) caused thermal decomposition of the CFRP due to its limited thermal resistance, leading to interfacial defects such as cracks and pores. The interface between the CFRP and TC4 coating primarily comprised granular TiC and acicular α′ martensite, with minor TiS₂ detected. Optimal mechanical performance was achieved at a laser power of 250 W and a scanning speed of 1.2 m/min, yielding a maximum interfacial shear strength of 18.5 MPa. These findings provide critical insights for enhancing the load-bearing capacity of TC4/CFRP aeronautical composites, enabling their reliable operation in extreme aerospace environments. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

30 pages, 6502 KB

Open AccessArticle

Sustainable Medical Materials: AI-Driven Assessment for Mechanical Performance of UVC-Treated Date Palm Epoxy Composites

by Mohamed A. Aboamer, Abdulrahman Hakami, Meshari Algethami, Ibrahim M. Alarifi, Tarek M. A. A. El-Bagory, Ahmad Alassaf, Bakheet A. Alresheedi, Ahmad K. AlOmari, Abdulaziz Abdullah Almazrua and Nader A. Rahman Mohamed

Polymers 2025, 17(8), 1125; https://doi.org/10.3390/polym17081125 - 21 Apr 2025

Viewed by 1220

Abstract

This study investigates the AI-assisted analyses of radiation disinfection effects on the mechanical properties of recycled date kernel powder–epoxy composites for medical applications, utilizing Euclidean distances and the k-nearest neighbor (KNN) algorithm. Tensile and compression tests were conducted on twenty specimens following ASTM [...] Read more.

This study investigates the AI-assisted analyses of radiation disinfection effects on the mechanical properties of recycled date kernel powder–epoxy composites for medical applications, utilizing Euclidean distances and the k-nearest neighbor (KNN) algorithm. Tensile and compression tests were conducted on twenty specimens following ASTM standards, with the data analyzed using a t-test to evaluate the impact of the UVC disinfection process on the material’s mechanical properties. The application of AI through the KNN algorithm successfully identified the three most representative curves out of five for both tensile and compression tests. This targeted curve selection minimized variability and focused on the most relevant data, enhancing the reliability of the analysis. Following the application of UVC and AI, tensile tests showed a 20–30% increase in ultimate stress. Similarly, compression tests revealed a 25% increase in transition stress, an 18–22% improvement in ultimate stress, and approximately a 12% rise in fracture stress. This research underscores the potential of combining AI, sustainable materials, and UVC technology to develop advanced composites for medical applications. The proposed methodology offers a robust framework for evaluating material performance while promoting the creation of eco-friendly, high-performance materials that meet the stringent standards of medical use. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

Review

Jump to: Research

25 pages, 9831 KB

Open AccessReview

Web Crippling of Pultruded GFRP Profiles: A Review of Experimental, Numerical, and Theoretical Analyses

by Mohamed Ahmed Soumbourou, Ceyhun Aksoylu, Emrah Madenci and Yasin Onuralp Özkılıç

Polymers 2025, 17(20), 2746; https://doi.org/10.3390/polym17202746 - 14 Oct 2025

Cited by 2 | Viewed by 1310

Abstract

Glass fiber reinforced polymer (GFRP) composite profiles produced by pultrusion method are widely used as an alternative to traditional building materials due to their lightness and corrosion resistance. However, these materials are susceptible to crushing type fractures known as “web crippling” especially under [...] Read more.

Glass fiber reinforced polymer (GFRP) composite profiles produced by pultrusion method are widely used as an alternative to traditional building materials due to their lightness and corrosion resistance. However, these materials are susceptible to crushing type fractures known as “web crippling” especially under local loading due to their anisotropic structure and limited mechanical strength. Understanding web-crippling behavior is crucial for the safe and efficient structural application of pultruded GFRP profiles. This study report narrated the review of experimental, numerical, and analytical investigations of web-crippling behavior of pultruded GFRP profiles. Highlights of the major findings include profile geometry and detailing of the flange–web joint, loading types (end-two-flange (ETF), interior-two-flange (ITF), end bearing with ground (EG), interior bearing with ground (IG)), bearing plate dimensions, presence of web openings, and elevated temperatures. It also considers the limitations of current standards, along with new modeling techniques that incorporate finite element analysis as well as artificial intelligence. Damage types such as web–flange joint fractures, crushing, and buckling were comparatively analyzed; design approaches based on finite element modeling and artificial intelligence-supported prediction models were also included. These insights provide guidance for optimizing profile design and improving predictive models for structural engineering applications. Gaps in current design standards and modeling approaches are highlighted to guide future research. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (14 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI