Journal of Polymer Research最新文献

Polymers tailored with different nanofillers are potentially used to fill the gaps of conventional materials for various engineering applications. This can be done because of the exceptional synergistic properties of nanofillers and polymers. Nanofillers have unique mechanical, electrical, and thermal properties. They can be reinforced with the flexible polymer matrix to develop advanced polymer nanocomposites and achieve great engineering performance. The nanofillers tailored nanocomposite have enhanced synergistic properties and functionality, which make it suitable for various engineering applications such as automotive, structural health monitoring, aerospace, coating, electronics devices, biomedical devices, and others. Polymer nanocomposites synthesized using techniques such as in-situ polymerization, the melt intercalation method, the solution intercalation method, and the mixing method showed improved properties. To obtain the polymer nanocomposite with the required quality and performance, we need to consider essential design parameters such as nanofiller types, concentrations, shapes, dispersity, sizes and interfacial relations during the design and optimization processes. The performance and properties of polymer nanocomposites evaluated by using the rheological tests, thermogravimetric analysis (TGA), micromechanical analysis, and dynamic mechanical analysis (DMA) showed the enhanced synergistic properties compared to the pure polymer material.

This study describes the combination of unique properties of lignin with TiO₂ as an innovative and effective preparation method for high-performance flame-retardant additives that may be utilized as polymer coatings. The use of lignin resulted in numerous advantages including an increased number of functional groups, satisfactory biocompatibility, low toxicity, and high carbon content. The major benefit of lignin is associated with the reduced carbon footprint of the manufactured product. Lignin can be classified as a natural flame-retardant agent owing to the high amount of char formed during combustion. In turn, TiO₂ exhibits high chemical stability and low operating costs and is considered a non-toxic and environmentally friendly material. During the experiments, commercial TiO₂ in anatase crystallographic form, TiO₂ synthesized from titanyl sulfate hydrate, and kraft lignin as well as organic–inorganic hybrid materials composed of these materials were evaluated as functional additives in epoxy-resin-based polymer coatings (Epidian 601) and their properties were investigated in detail. The cone colorimetry test confirmed that the obtained hybrids are effective flame-retardant additives for polymer coatings, with a notable fire hazard reduction observed for samples containing a synergistic system of titanium oxide and lignin. The coating with lignin was the most effective in fire suppression processes. The conducted thermal and mechanical investigations confirmed good performance properties of the coatings indicating thermal resistance up to 360 °C and Shore D hardness in a range of 80.36–86.28°Sh, accordingly. Optical profilometry investigations show that the lignin/TiO₂ hybrids exhibit a stable topological surface shape as well as good dispersion and uniformity in the polymer matrix. All the conducted tests allowed confirmation that the presence of functional additives in polymer coatings in the form of lignin and TiO₂ can be a promising alternative to non-biodegradable synthetic materials which improve flame-retardant properties.

Existence of pollutants in water sources is a global worry that needs the expansion of novel and efficient solutions. This study aimed to synthesize porous organic polymers (POPs) from triazine and di-aminopyridine to effectively eliminate the Congo red (CR) dye from water environments. Two porous organic polymers based on imine (POP-IB) and amine (POP-AB) groups were synthesized from the reaction of diamino-pyridine with trialdehyde for POP-IB and cyanuric chloride for POP-AB. The synthesized POPs were charactized by different techniques and exhibit good thermal and chemical stability, rendering them ideal for the removal of CR dye from aqueous solutions. Additionally, our study examined the optimization process, which involved adjusting various parameters such as pH, time duration, initial dye concentration, and the amount of adsorbent. The study showed that the maximum adsorption capacities for the CR dye were 104 mg g⁻¹ with POP-IB at pH 6 over 240 min, and 63 mg g⁻¹ with POP-AB at pH 5 over 180 min, respectively. Kinetic models suggest that the adsorption of CR dye onto these adsorbents is most accurately described by the pseudo-second-order. Moreover, the Langmuir isotherm provides the closest correlation with the adsorption isotherms for both POPs.

Lignocellulosic natural fibers are increasingly utilized as reinforcements in thermoset matrix composites, driven by economic and environmental demands. Sugarcane bagasse, a byproduct of the sugar industry, is a particularly promising source of these fibers. This study thus explores the development of sustainable composites by incorporating sugarcane bagasse fibers into bio-epoxy and unsaturated polyester resin matrices. Chemical treatments, including alkali, silane and oxalic acid, were applied to enhance fiber-matrix adhesion and improve mechanical, thermal and physical properties. The physical measurements revealed that chemical modifications of the bagasse have a significant impact on the density, water absorption and wettability of both thermosetting matrices. Additionally, SEM analysis revealed variations in composite morphology, such as brittle matrix failure, fiber breakage, fiber pullouts and voids, with the alkali-treated fibers exhibiting the best fiber-matrix interface for both types of resins. The mechanical testing of the composites reinforced with untreated and chemically treated sugarcane bagasse particulates revealed distinct variations in tensile strength and modulus, flexural strength and modulus, impact strength and hardness cross the different treatments. Superior mechanical performance was observed for the alkali treated specimen. Similarly, from the degradation temperatures and activation energies from the thermal analysis, the alkali treated fibers provided better thermal stability. These findings highlight the potential of sugarcane bagasse in eco-friendly composite design, though further research is needed to optimize treatments for better performance.

Graphene oxide (GO) was produced by exfoliating natural flake graphite using Hummers’ method. Using the ionic liquid 1-allyl-3-methyl-imidazolium chloride (AMICl), the surface characteristics of the GO sheets were carefully altered to form nanocomposites containing ethylene-propylene-diene monomer (EPDM), styrene-butadiene rubber (SBR), and functionalized GO (GO-IL). The research showcases the incorporation of a reinforcing filler, GO-IL, as opposed to GO alone, leading to significant improvements in both the mechanical properties and swelling resistance of 80/20 EPDM/SBR blend nanocomposites. The distinctive amphiphilic nature of GO-IL facilitated its interaction with EPDM/SBR, thereby substantially enhancing the mechanical properties and swelling resistance of the composite system. With incorporation of only 6 phr GO-IL, the tensile strength and stress at 100% elongation of EPDM/SBR blend increased by 257% and 135%, respectively. This study indicates that GO-IL holds promise as a viable reinforcing filler for EPDM/SBR blends.

Self-healing composites are smart materials that can self-detect and prevent micro crack propagation and any catastrophic failure in the composite structure. In this study, dicyclopentadiene (DCPD) monomer was encapsulated with urea formaldehyde (UF) by in situ polymerization. These microcapsules were mixed with epoxy, chopped carbon fiber (CF), and multi-walled carbon nanotubes (CNT) to make self-healing composite. Both microcapsules and the composite specimens were extensively tested for their physical, thermal, and mechanical properties. The average diameter and shell thickness of the microcapsules were 268 µm and 805 nm, respectively. DMA analysis suggested that the microcapsules have a glass transition temperature (T_g) of 85°C. FTIR analysis confirmed the presence of CF, multi-walled carbon nanotubes (MWCNT), and other constituents in the composite. The tensile strength of the self-healing composites was tested as per ASTM standards. The incorporation of MWCNT in the composites has significantly improved the tensile strength of the composite without compromising on the self-healing efficiency (90%) compared the unmodified samples (72%). The encouraging results of higher glass transition temperature (85°C) combined with an improved healing efficiency (90%), can be considered as the novelties of this work. As the test results of microcapsules and composite specimens were encouraging, they can find applications in making composite structures for aerospace, windmills, and marine applications. The experimental observations and test results are discussed in detail.

Herein, composite films were fabricated using the solution casting route, incorporating different weight percentages of crystal violet (CV) into polyvinyl alcohol (PVA). To examine the final composites, a series of characterization approaches were used. Fourier-transform infrared spectroscopy (FTIR) elucidated PVA/CV molecules’ physicochemical interactions. The analysis through X-ray diffraction (XRD) pointed out a decrease in the semi-crystalline nature of the polymer matrix with a rise in the CV content, thereby enhancing transport mobility and electrical conductivity. The optical properties of PVA influenced by CV dopants were systematically studied in the range of 190–1400 nm. Notably, the PVA/CV composites exhibited improved UV-blocking capabilities in the 190–380 nm range, making them appropriate for uses including UV notch filters and laser hindering filters. An increase in CV doping percentage from 0.1 to 0.8 wt% resulted in a reduction of the indirect optical bandgap of PVA from 5.16 ± 0.013 eV to 4.77 ± 0.069 eV. Additionally, the Wemple-DiDomenico model revealed significant enhancements in the optical parameters. Specifically, the dispersion energy and oscillator energy of PVA/CV composites increased from 0.91 eV and 2.01 eV to 6.83 eV and 3.25 eV, respectively, along with an increase in the lattice dielectric constant (ε_L) from 1.71 to 3.47. These improvements in dispersion factors were attributed to the cross-linking of CV with the polymer matrix. Furthermore, the composite films demonstrated notable nonlinear optical properties, indicating their potential for practical applications in photonic and optoelectronic devices.

Ethylene-vinyl acetate (EVA)grafted 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane (V4) polymer EVA-g-V4 was prepared by free-radical solution grafting reaction. The results of the purified grafted products by FT-IR, ¹H NMR, XRD, TG and DSC show that V4 has been successfully grafted onto the main chain of EVA. The effects of the dosage of V4 and BPO on grafting ratio were studied. When the dosage of V4 was 6.0 wt%, and the dosage of BPO was 0.8 wt%, the grafting ratio was up to 1.4%. The cross-linking behaviour was verified by SEM. Compared with pure EVA film, the peel strength, mechanical properties, volume resistivity and hydrophobicity of EVA-g-V4 film all improved with increasing grafting ratio. This work provides a new option in the field of photovolatic encapsulation materials.

The mechanical qualities of natural fiber (NF) -based polymer composites are superior, making them advantageous and these composites are environmentally beneficial. The current investigation involved the fabrication of hybrid composites using Calotropis gigantea (CGF) and Abaca Fiber (AF) as reinforcements in epoxy matrix. The hand layup technique was employed for the fabricating process. Subsequently, the composites were investigated and analysed for their water absorption rate, tribological performance, and mechanical properties. This study aims to uncover a noteworthy combination of NF reinforced polymer composites that can be utilized in commercial Engineering applications. The mechanical properties were examined by measuring their hardness, impact resistance, flexural strength (FS), Compressive strength (CS), and tensile strength (TS). Furthermore, the broken surfaces of tensile sample were inspected utilizing a scanning electron microscope. Composite specimens were immensed in distilled water and their water penetration percentages were measured to ascertain their water absorption (WA) properties. The tribological performance was analysed utilizing a pin-on-disc equipment to assess the specific wear rate and coefficient of friction. The outcomes demonstrated that the hybrid composites surpassed the single-fiber composites in all variations. Sample G exhibited superior properties in all combinations, with a TS of 36.19 MPa and tensile modulus of 328.95 MPa. Additionally, it shows that higher flexural strength of 43.85 MPa and flexural modulus values of 350.84 MPa. Furthermore, it demonstrated higher Compressive strength of 94.45 MPa and modulus values of 576.93 MPa. Moreover, it exhibited a higher impact value of 53.88 kJ/m² and higher hardness value of 44.07 HV. This material is well-suited for non-structural uses in electronics and electrical insulating boards and components, as the results show that a combination of CGF and AF fibers with an epoxy matrix improves mechanical qualities.

The effects of density and shape of hollow silica (functionalized silica hollow tubes (FSHT) or hollow glass microspheres (FHGM)) on dielectric constant (ε_r) and dielectric loss (tan δ) of hindered phenol (HP) grafted functional polypropylene (FPP)/FSHT, heat-treated FPP (HTFPP)/FSHT, FPP/FHGM or HTFPP/FHGM substrate films were systematically investigated. The dielectric or free-volume-hole characteristics of FPP/FSHT, FPP/FHGM, HTFPP/FSHT, or HTFPP/FHGM films decrease to a minimum, as FSHT or FHGM contents approach an optimal value of 4wt% or 8wt%, respectively, and their dielectric or free-volume-hole characteristics decrease or increase gradually with increasing HP molar%. The minimum ε_r and tan δ of FPP/FSHT or HTFPP/FSHT films decrease significantly with decreasing FSHT’s densities. By filling with 0.46 g/cm³ identical density of hollow silica fillers, the minimum ε_r or tan δ procured for FPP/FSHT or HTFPP/FSHT films are somewhat smaller than those of corresponding FPP/FHGM or HTFPP/FHGM films. The linear coefficient of thermal expansion (LCTE) or onset degradation temperature (DT_onset) of FPP/FSHT, HTFPP/FSHT, FPP/FHGM or HTFPP/FHGM films reduce or increase visibly with increasing FSHT or FHGM contents, respectively. All DT_onset values of HTFPP/hollow silica films are ~ 150℃ higher than those of conventional PP polymers. Satisfactorily low ε_r/tan δ (1.74/0.0019, 1.83/0.0020, 1.83/0.0024 and 1.92/0.0028 at 1 MHz), LCTE (95 × 10^–6/℃, 89 × 10^–6/℃, 80 × 10^–6/℃ and 74 × 10^–6/℃) and pleasing heat-resisting properties for 6G ultrarapid communication are acquired for properly prepared FPP/FSHT, HTFPP/FSHT FPP/FHGM or HTFPP/FHGM substrate films having 1.2 HP molar% and 0.46 g/cm³ density of FSHT and FHGM fillers. Probable reasons accounting for these reduced dielectric, LCTE and improved heat-resisting characteristics are proposed.