Iranian Polymer Journal最新文献

Fouling is a serious problem during membrane application. To improve antifouling performance, we substituted tannic acid (TA) with the milder tartaric acid. This modification using synthesized TA-modified tannins (denoted as ta-f-TA) with longer molecular chains, are less susceptible to leaching. A high-throughput polyvinylidene fluoride (PVDF) antifouling membrane was prepared by blending it with amphiphilic polymer poly(vinylidene fluoride)-graft-poly(ethylene glycol) methyl ether methacrylate (PVDF-g-PEGMA) synergistically. Compared with the pristine membranes, the modified membranes (M0-M2) had increased porosity and average pore size, reduced sponge-like structure, and progressively formed through-pores. Their hydrophilicity and filtration properties were significantly improved. The complete wetting times of the membranes were 50, 30 and 23 s. With moderate addition of ta-f-TA (0.25–0.5 g), the increase in hydrophilicity and roughness of the membranes had a synergistic effect on improving the antifouling performance of the membranes. Among them, membranes M1 and M2 exhibit comparable filtration performance. However, after cyclic testing, M1 maintained stable operation while M2 was ruptured due to inferior mechanical properties. Considering practical applications, M1 delivers optimal performance. Its pure water flux and sodium alginate retention rate reached 1294.61 L/(m² h) and 88.64%, respectively. Furthermore, the M1 membrane exhibits strong tolerance, maintaining optimal filtration performance under harsh conditions such as strong acids, weak acids, weak alkalis, and high salinity.

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High density polyethylene composites have been prepared by melt mixing method along with microencapsulated intumescent fire retardant additives. The additive was synthesized using ammonium polyphosphate and charring agent (propane terephthalamide), microencapsulated in melamine formaldehyde resin. The prepared composites were evaluated for mechanical, thermal and fire retardancy properties. The results revealed that as the microencapsulated additive in the composites increased from 0 to 18%, the tensile and compressive strength increased by about 8% and 21%, respectively, and gradually reduced to 10% and 15% with increase in microencapsulated additive content up to 40%. The tensile and compressive modulus gradually increases by about 5% and 29%, respectively, as the microencapsulated additive content increases from 0 to 40%. The tensile fractured morphology and dispersion of additive in the composites were studied using scanning electron microscopy and transmission electron microscopy, respectively. Fire retardancy of the HDPE composites loaded with 40% microencapsulated additive, resulted in significant reduction in heat release rates, enhancing their thermal stability and formation of thick compact char residue. Thus the effect of variations in microencapsulated additive content on the mechanical properties, thermal behavior and fire retardancy of the composites is systematically investigated which would be beneficial in naval applications, such as in workboats hulls, cables and buoys and are suitable for other offshore environments.

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Lightweight composites with high electromagnetic interference (EMI) shielding capability and mechanical properties are urgently needed in spacecraft, aircraft and other industrial areas. Herein, layers of carbon fibers and polyester reinforced epoxy composites were designed and prepared with different structure arrangements via vacuum-assisted resin transfer molding, where a sandwich structure was used to prepare carbon fiber-polyester/epoxy resin (CF-PET/EP) composites. The results showed that EMI shielding effectiveness (SE) of carbon fiber/epoxy resin (CF/EP) composites increased with the number of CF layers, reaching 50.92 dB when the layer number was four. On the other hand, the EMI SE of CF-PET/EP composites was improved by adding PET layers between CF layers. Due to the constructed sandwich structure, the EMI SE of CF-PET/EP composite was higher than that of the pure CF/EP composites. In addition, with a fixed PET layer number, the EMI shielding performance of CF-PET/EP composites increased with the increase of CF layers, and the SE reached 57.96 dB with six CF layers. Finally, the tensile and bending properties of CF-PET/EP composites decreased where a large number of PET layers was used due to the poor mechanical properties of PET. This work offers valuable guidance for preparing lightweight, mechanically robust and excellent EMI-shielding CF-reinforced composites for practical applications.

In many production-oriented businesses today, there is a growing trend to replace non-sustainable raw materials with environmentally friendly alternatives. In contrast to synthetic fiber reinforced composites, natural fiber reinforced composites are generally exhibit lower resistance to mechanical loads and chemical impacts. Consequently, researchers have been working to enhance the strength of natural‑fiber composites for a variety of applications. In this work, silicon carbide (SiC) particles were employed as fillers to investigate the morphological features and mechanical performance of epoxy composites reinforced with Elettaria cardamomum (cardamom) fibers. The primary objective of this work was to demonstrate the potential of natural fibers by incorporating biodegradable, eco-friendly cardamom fibers into polymer composites. The fibers from Elettaria cardamom plants pseudo stems after being chopped and alkali-treated were used to prepare composite samples via a hand‑lay‑up technique. In this case, 5% silicon carbide (SiC) particles with a granule size of 4.5 μm were mixed with 30% Elettaria cardamom fibers to fill the composites. The mechanical characteristics including tensile, flexural and impact strengths of Elettaria cardamom fiber reinforced epoxy composites containing silicon carbide particles were then evaluated. Field-emission scanning electron microscopy (FESEM) was employed to examine the internal surface morphology and fiber-matrix adhesion of the composites both prior and after mechanical testing. The results indicated that the addition of SiC particles significantly improved the tensile, flexural, and impact resistance of the epoxy-cardamom fiber composites, highlighting the feasibility of using biodegradable natural fibers in high performance composite materials.

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Durability remains a major challenge restricting the large-scale utilization of natural fiber-reinforced composites in marine environments. Continuous exposure to seawater often induces hydrolysis, matrix plasticization, fiber swelling, and fiber-matrix interfacial debonding, leading to severe deterioration in performance. In this work, the effect of molybdenum disulfide (MoS₂) modification of epoxy resin on the seawater aging resistance of epoxy/sisal fiber (Ep/SF) composites was systematically investigated. Composite laminates were fabricated using the hand lay-up process and subjected to accelerated seawater immersion for two months. Characterization techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) were employed to elucidate structural and thermal modifications, with particular emphasis on the role of silane-treated fibers and MoS₂ incorporation. Mechanical performance was assessed through tensile, flexural, impact, hardness, and interlaminar shear strength (ILSS) measurements. Results demonstrated that MoS₂-modified epoxy in conjunction with silane-treated sisal fibers exhibited superior resistance to seawater-induced degradation, maintaining higher mechanical integrity compared to untreated systems. Additionally, tribological analysis confirmed that these hybrid-modified composites displayed enhanced wear resistance and reduced coefficient of friction. The findings indicated that MoS₂ modification reduced water absorption by 42.7% (from 1.302% in Ep/SF to 0.746% in SMoS₂-Ep/SSF) and decreased the friction coefficient by 14.8% (0.27→0.23), with smaller reductions in tensile, impact, flexural, and ILSS properties after 2 months of seawater exposure.

Recycled polypropylene (RPP)-based nanocomposites reinforced with graphene (GNP) and/or zinc borate (ZB) were prepared with two different weight fractions (0.5 and 1). This study focused on RPP-based hybrid nanocomposites containing both GNP and ZB reinforcements, investigating their mechanical, thermal, and tribological properties. The hybrid nanocomposites were produced via twin-screw extrusion and injection moulding. Mechanical properties were evaluated through tensile, hardness, and Izod impact tests, while dynamic mechanical analysis (DMA) was performed to examine the storage modulus. Abrasion and friction tests were also conducted to assess tribological behaviour. Incorporation of ZB into RPP improved the elastic modulus by up to 62%, while yield strength increased by 10% compared to pure RPP. Slight enhancements in hardness and impact strength were also observed. Hybrid RPP-GNP-ZB nanocomposites exhibited higher stiffness and improved post-yielding behaviour than single-reinforced and pure RPP samples. DMA results indicated that GNP has a more pronounced effect on the storage modulus than ZB, and hybrid nanocomposites maintained improved thermo-mechanical performance up to 120 °C. Tribological tests demonstrated that higher reinforcement contents were associated with increased wear rates. Static and dynamic friction coefficients increased slightly with ZB and more notably with GNP. According to these findings, GNP and ZB reinforcements in recycled polypropylene measurably enhance mechanical and dynamic mechanical properties, highlighting the potential for high-performance polymer applications.

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A growing apprehension about global warming has sparked a pursuit among the scientific community to produce ecological friendly substances that may mitigate carbon effects. The atmospheric and ecological features of natural fiber-based composites have had substantial consequences in the field of sustainability. This research investigates how different tool characteristics, such as feed rate and cutting speed, affect the drilling performance of composites based on silanized Corchorus olitorius particles. A number of trails are undertaken to quantify the influence of feed and cutting speed on multiple variables which involves drill force, material removal rate, roundness inaccuracy and surface roughness. The findings demonstrated that the arrangement of drilling has had an immense impact on the emergence of flaws in the vicinity of periphery hole. With an 8 mm drill bit, the lowest feed rate (20 mm/rev) and maximum cutting speed (2000 rpm) resulted in the lowest thrust force (44.25 N) and surface roughness (1.256 μm). On the other hand, maximum values occurred with greater feed rates and lower cutting speeds. In order to identify the potential drilling attributes of established composite substrate, some machine learning models have been devised. Among these models, the support vector machines model has achieved the greatest accuracy (R² up to 0.951). These findings illustrate the composite’s viability for lightweight residential applications because of its machinability, cost-effectiveness, and satisfactory mechanical performance.

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Hybrid natural-synthetic fiber composites provide a great combination of strength, sustainability and cost-effectiveness. This research explores the viscoelastic properties of sisal/e-glass fiber-reinforced hybrid composites loaded with graphene nanoplatelets. These specimens comprised pure sisal fiber composite (SFC), pure glass fiber composite (GFC), and hybrid fiber (HFC) composites. Graphene was included within the hybrid fiber composite (GHC), with varying weight percentages of 0.25%, 0.5%, 0.75%, and 1%. Dynamic Mechanical Analysis (DMA) was employed to assess storage modulus, loss modulus, and damping factor. Results revealed dependencies on the frequency and nano additive content. GFC exhibited higher storage modulus, loss modulus and lower damping factor compared to SFC. Hybridizing of sisal and e-glass fibers, resulted in an intermediate storage modulus, loss modulus and damping factor. Addition of graphene in hybrid composite influenced all three properties. Low concentration of graphene incorporation reduced storage and loss modulus due to insufficient interaction with the matrix. High concentrations of graphene lead to agglomeration, resulting in non-homogeneous distribution and a reduction in storage and loss modulus. 0.5% (by wt) yielded highest storage modulus and loss modulus showing superior energy dissipation capabilities. For high damping applications, hybridization of glass fiber composite with sisal fibers along with addition of 0.25% (by wt) graphene enhanced the damping properties by 16% and 15% at 1 Hz and 10 Hz, respectively over pure glass fiber composites. For low damping applications, sisal fiber has to be hybridized with glass fibers and incorporation of 0.5% (by wt) of graphene decreases the damping factor by 53% and 57%, respectively, at 1 Hz and 10 Hz over pure sisal fiber composites.

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Hydroxyl-functionalized graphene nanoplatelets (GOH) were incorporated into an epoxy resin at concentrations of 0.1, 0.5, 1 and 3 parts per hundred resin (phr). The curing system, based on dicyandiamide as a solid curing agent and 1-methylimidazole as an accelerator, was homogeneously mixed. The curing behavior of the resulting nanocomposites was evaluated using differential scanning calorimetry (DSC). Unidirectional carbon fiber/epoxy nanocomposites were fabricated through hot pressing after fiber impregnation with the modified resin. Mechanical testing was conducted to assess the transverse tensile strength of the unidirectional carbon fiber-reinforced epoxy (UCFRE) composites and to compare the experimental results with theoretical predictions. Further evaluations included flexural strength, fracture toughness, interlaminar shear strength (ILSS), and lap shear strength (LSS). Additionally, the synergistic effect of a hybrid nanoparticle system consisting of 0.4 phr GOH and 0.1 phr carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs) on composite performance was investigated. The results showed that adding 1 phr GOH improved the transverse tensile strength and strain-at-break by 17.6% and 20%, respectively. A more pronounced enhancement (60%) in transverse strain-at-break was observed at 0.5 phr GOH. Furthermore, at 1 phr GOH, longitudinal flexural strength, deflection-at-break, and flexural modulus increased by 6.8%, 6.9% and 6.9%, respectively. The incorporation of 3 phr GOH significantly increased fracture toughness by 71% in the transverse direction and 42% in the longitudinal direction.

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Energy storage devices, such as supercapacitors, have gained tremendous importance in recent decades due to their potential applications in various technological fields. The primary issues with supercapacitor devices are low power density, retention time, and cyclic stability. This work introduces polyaniline (PANI) and its composites with iron dust as electrodes for supercapacitors. The materials were synthesized through in situ polymerization and characterized using UV/visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and thermogravimetric analysis. The UV/visible spectra show characteristic peaks of the emeraldine salt form of PANI, which exhibit a significant change in intensity and position after the formation of the composites with iron dust. The presence of benzenoid and quinoid units of PANI and their interaction with the iron dust were further confirmed by the FTIR spectra. SEM and EDX analysis revealed the incorporation of iron dust within the PANI matrix. TGA analysis indicated enhanced thermal stability of the composites in comparison to neat PANI. The synthesized materials were deposited on a gold sheet electrode for electrochemical characterization. Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were assessed by an electrochemical workstation. The PANI/Fe2 composites show a maximum specific capacitance of 517 F/g over a steady potential window of − 0.2 to 0.8 V at a fixed current density of 1 Ag^− 1. The cycling stability was 89.55% even after 1100 charge-discharge cycles.

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