Journal of Polymer Research最新文献

In the present framework, we aimed to elaborate intumescent composites polyurethane/ organically treated montmorillonite (PU/ OMMT) foams by the use of local “Bentonite” called “Maghnite”. These composites were elaborated via an in situ polymerization. The first stage relates to the organic treatment of the montmorillonite (MMT) using an alkylammonium (hexadecylamine C₁₆H₃₅N) in order to increase the interfoliate distance, resulting in an organically compatible modified montmorillonite (OMMT). The second one is reserved to the optimization of the polyurethane (PU) formulation. Composite’s foams (PU/ OMMT) are formulated via the free expansion process. Moreover, the physicochemical characterization of the developed foams was carried out. Characterization of the obtained foams have been done by various methods such as: FTIR, DSC, TGA, XRD, SEM, Charpy test, and normalized flammability test (UL 94 HB). FTIR analysis confirms the PU formation and the incorporation of the organically treated montmorillonite (OMMT) into the polyurethane (PU) via the in-situ polymerization. Add to that, it is assigned by the XRD analysis that the interfoliate distance has been increased from 11.63°A to 27.96°A using the hexadecylamine and the PU/ OMMT composite foams present a mixture of intercalated and exfoliated structure. The SEM images prove that the addition of 5 wt % of OMMT has resulted in similar cell size compared to the pristine PU formulation (about 100 µm). DSC and TGA analysis proved the good thermal stability of PU foams and confirmed that the PU/ OMMT composite foam is the most stable one. Regarding the fire behavior, the obtained foams are in accordance with the normalized flammability test. The strength and tenacity test revealed improved mechanical properties in comparison to those not treated.

Hydrogel as a temporary plugging material provides an efficient strategy to replace locally damaged oil pipelines. However, the poor mechanical properties and incomplete gel-breaking severely limit the practical application of this strategy. Herein, a temperature and pH-responsive hydrogel P(ACG-co-AM)-MMT was prepared by copolymerizing a natural amino acid derivative monomer N-acryloyl glycine (ACG) and acrylamide (AM) with montmorillonite (MMT) as filling material. Hydrogen bonding is the main driving force in hydrogel formation, as confirmed by infrared spectroscopy. The introduction of MMT plays a key role in enhancing the mechanical properties of hydrogels. This successfully overcame the issues of inadequate mechanical properties-rapid degradation trade-off in hydrogel temporary plugging materials. The results show that the hydrogel can withstand the pipeline pressure up to 84 kPa and effectively plug the pipeline. Due to the reversibility of hydrogen bonds, the hydrogel can realize the transformation of sol-gel-sol under temperature stimulation. The plugged area of the pipeline is removed by injecting thermal-produced water. When the hot water temperature is 85 ℃, the pipeline changes to the dredging state only 21 min, dramatically simplifying the operation time. P(ACG-co-AM)-MMT hydrogel has great potential as a temporary plugging material in replacing partially damaged oil pipeline plugging operations.

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Poly(lactic acid) (PLA) as shape memory material has gained attention due to its biocompatibility, biodegradability, and ease of processing by 3D printing. PLA’s environmentally friendly nature makes it an attractive candidate for sustainable and recyclable shape memory applications. However, PLA’s slow shape recovery rate and low shape fixation percentage hinder its applicability as shape memory material. In the present study, we report MXene-modified PLA (PLA/Mx) nanocomposite with enhanced shape memory effect. Solution processing methods mediated the loading of the MXene in the PLA matrix. Different samples were prepared by varying the weight% of the MXene in the PLA matrix. The structure and morphology of samples were analyzed by XRD and TEM characterization. Thermogravimetric analysis was performed to measure the thermal stability of the composite. Compared with pure PLA, with MXene loading, the PLA/Mx composites show an increase in thermal. The shape recovery study on PLA/Mx samples used temperature as an external stimulus. The PLA/Mx composite exhibited a significantly improved shape memory effect than the PLA alone. The study exhibits that a shape memory effect can be improved by tuning the MXene additive loading in the PLA matrix. The material shape recovery effect was validated by fabricating the spiral structure. The fast shape recovery time 3s and shape fixation/recovery of > 95% was observed for 1 wt% of PLA/Mx. The PLA/Mx composite is expected to contribute significantly to implementing innovative shape memory applications, particularly in the biomedical field for sutures, controlled drug release, and minimally invasive devices.

Experimental studies of polymer solutions have been carried out at different scattering angles using Dynamic Light Scattering method to investigate the polymer solutions at and around a few defined concentrations (critical) in terms of their morphological change that results in the homogeneity/heterogeneity of the solutions. Critical concentrations were identified from the study of concentration dependent behavior of polymer solutions as a result of optimum heterogeneity/homogeneity at that concentration. Correlation functions of polymer solutions at critical concentrations were analyzed as a function of pH change of the solutions as well as with the change of different molar concentrations of NaCl solutions. An increase in heterogeneity of the solutions with the change of the pH value or with the change of molar concentrations of NaCl was found to be observed as a result of the increase of stretching exponent of slow mode of the solutions. Additionally, variations of Zeta potential study with pH change and with change of molar concentration of NaCl at different concentrations of polymer solutions show the standard desired equilibrium stability value of the studied solutions.

This study investigates the enhancement of mechanical properties in a sodium alginate-polyacrylamide double network (DN) nanocomposite hydrogel enhanced with silver nanoparticles (Alg-g-PAAm/nAg). This hydrogel utilizes both thermal and ionic cross-linking methods (MBA and CaCl₂) to develop a robust matrix with outstanding mechanical and thermal properties. The Alg-g-PAAm/nAg DN nanocomposite hydrogel demonstrated a fracture stress of 1255 kPa, an elastic modulus of 200 kPa, and an exceptional toughness value of 520,000 kJ/m³. Furthermore, the material’s response to swelling in various pH and temperatures was analyzed through swelling studies, revealing significant pH sensitivity. The incorporation of silver nanoparticles (Ag NPs) within the nanocomposite significantly enhanced both its mechanical strength and stability, as well as its antibacterial performance. Antimicrobial assays against Staphylococcus aureus and Escherichia coli demonstrated pronounced inhibition zones, indicating the hydrogel’s potent antibacterial properties. This dual enhancement makes the composite highly suitable for various demanding biomedical applications. The comprehensive analytical techniques employed, including FT-IR, FE-SEM, TEM, and TGA, confirmed the successful integration of the Ag NPs within the nanocomposite structure and underscored the material’s potential in fields such as tissue engineering, drug delivery systems, and advanced wound dressings.

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A carbamate surfactant was synthesized using octadecanol polyoxyethylene ether(AEO) and isocyanatoethyl methacrylate(IEM) as functional monomers. Subsequently, active-carbamate-surfactant-modified PER nanomicrospheres were prepared through two-phase aqueous dispersion polymerization, utilizing acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and ethylene glycol dimethacrylate (EGDMA) as raw materials. The microstructures and properties of the nanomicrospheres were characterized and examined using infrared spectroscopy, nanolaser particle size analysis, thermogravimetric analysis, scanning electron microscopy, rheometry, rotating drop ultra-low interfacial tensiometry, and core-driven experiments. The results revealed that the synthesized PER nanomicrospheres exhibit a uniform particle size distribution, with an average particle size of 336 nm. Furthermore, the nanomicrospheres exhibit a thermal decomposition temperature of 278℃, demonstrating good thermal stability. The nanomicrospheres also exhibit favorable expansion and viscoelastic properties. Upon the injection of 3wt.% of the PER nanomicrospheres into a non-homogeneous core, the blocking rate (η) reaches 90.32%, while the recovery rate increases by 30.2%. This improvement is attributed to the unique structural design of the nanomicrospheres, allowing them to form a thin film at the three-phase oil–water-rock interface and promoting oil emulsification and stripping. Overall, the PER nanomicrospheres effectively control fluid dynamics within reservoirs, mitigate the loss of oil and gas resources, enhance the economic benefits of oil and gas fields, and thus demonstrate good application prospects.

To improve the antioxidant capacity of polyethylene (PE), ginkgo biloba leaf extract (GBLE) was introduced into the PE matrix as a natural stabilizer for the first time. The effect of GBLE on the thermal oxidation stability, thermal stability, processing stability, mechanical properties, and long-term aging resistance of PE during multiple extrusion processing was investigated. The oxidation induction time (OIT) results showed that the addition of GBLE improved the thermal oxidation stability and long-term aging resistance of the PE matrix even after multiple extrusions. Additionally, thermogravimetric analysis revealed that GBLE significantly enhanced the thermal stability of the polymer matrix. These improvements could be attributed to the potent free radical scavenging efficiency of GBLE. OIT tests also confirmed GBLE’s resistance to extraction from the PE matrix, as well as its antioxidant activity after extraction. Moreover, the introduction of GBLE effectively enhanced the processing stability of the PE matrix, with the melt flow rate of PE-GBLE_2.0 decreasing by only about 0.17 g/10 min from the first extrusion to the fifth extrusion. Furthermore, the addition of GBLE could still maintain the good mechanical performance of the matrix after multiple extrusions. All results demonstrated that GBLE is an effective and natural multifunctional stabilizer for PE.

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Various sectors are utilizing composites reinforced with natural fibers (NF). Composite materials with an epoxy matrix have been mould with hand layup process using woven fibers from the Terminalia Arjuna fiber and Moringa Oleifera fruit fibers. The composite panels were manufactured using a variable number of layers, ranging from 7 to 13, depending on the fabric's weight. An assessment has been conducted on the tensile, bending, impact, compression, short beam shear strength, fracture toughness, and water-absorption (WA). The composites that were created were examined utilizing SEM analysis to examine the fractured morphology and assess the strength of the interface. The investigation revealed that augmenting the quantity of fiber layers enhanced the physical and mechanical properties of the composites. The tensile strength of the composites increased by 25% to 62.35 MPa with 11 layers, while water absorption was found to be 18.4% after 10 days. Therefore, these findings suggest that the fabricated composites are well-suited for applications in structural components and automotive body parts requiring moderate load-bearing capacity.

This study focuses on developing and characterizing of fluorescent cellulose-based hydrogelsfor efficient chromium (Cr(VI)) adsorption. For this purpose, microcrystalline cellulose (MCC) was first surface-modified to achieve solubility using succinic anhydride. Cellulose succinate (CS) subsequently was grafted with a mixture of acrylic acid (AA) and acrylamide (AM), while N,N′-methylene-bis(acrylamide) (MBA) was added as crosslinker to obtain the final grafted and crosslinked hydrogels. To impart fluorescence and sensing capabilities, nitrogen-doped carbon quantum dots (N-CQDs) were synthesized via a microwave-assisted method using sugarcane bagasse, NaOH, and urea as precursors, and incorporated into the hydrogel. The resulting hydrogels demonstrated effective Cr(VI) adsorption, with optimal performance observed at 10% N–CQD loading. FTIR, SEM, rheological analysis, and TGA were employed for hydrogel characterization, while adsorption kinetics provided insights into the interaction mechanisms with Cr(VI).

The meta-aramid (PMIA) filter bag is one of the most common filter materials used in high-temperature exhaust filtration. However, the current understanding of the recycling of this material, and the durability and stability in multi-factor coupling environments is limited. In this work, the aging characteristics of PMIA filter bags under multi-factorial coupling were investigated, and the effect of the aging degree on the recycling. Firstly, the performance of the filter bags before and after aging was characterized by FT-IR, mechanical properties, SEM, and EDS analysis. The results show that the mechanical properties and thermal stability of the PMIA filter bag rapidly deteriorated under multi-factor coupling. Moreover, The PMIA can be completely dissolved in a LiCl-DMAc mixed solution. Therefore, LiCl-DMAc mixed solution can be used to dissolve used needle felt and prepare it into a thin film. The light transmission deteriorates of the recycled films made from aged needle felt, while still maintaining good tensile strength (σt) >55 MPa with Young’s modulus (E) >2 GPa. The effect of the aging degree of filter bags on the performance of recycled films was systematically investigated. The whole process does not cause environmental pollution. This study provides useful information for the degradation and recycling of PMIA.