Polymer Bulletin最新文献

The aim of this paper is to review the developments in the use of superabsorbent polymer (SAP) in cementitious materials. This review covers the classification, properties, and methods for testing SAP, along with its impact on concrete properties, and other noteworthy developments in SAP usage. Various methods can be used to test the water absorption by SAP. Among them, the tea bag method is considered a simple and time-saving test, while centrifuge and suction filtration methods are regarded as accurate because they remove inter-particle liquid. The water absorption by SAP is affected by factors such as SAP composition, method of preparation, physical characteristics, and properties of the fluid. Higher fluid temperature (e.g., 60 °C) leads to greater absorption and release distance, while higher pH levels (pH 13) result in lesser absorption. The optimal dosage of SAP varies between studies, generally ranging from 0.1% to 1.5%. Higher SAP content (0.3–8%) reduces workability and decreases slump. Results related to strength vary; some studies have reported increased strength due to SAP’s maintenance of higher internal relative humidity, while others have observed decreased strength due to increased porosity caused by SAP. The inclusion of SAP typically leads to a strength recovery of about 10% over time due to the continuous hydration process. Curing methods also influence strength, with sealed curing showing greater strength. Additionally, an increase in SAP dosage (0.1–0.6%) reduces shrinkage. Furthermore, the paper discusses the challenges encountered while using and testing SAP, as well as the explanations provided by researchers.

Noble metal nanoparticles (NMNPs) are crucial for catalytic processes, but their recycling and aggregation present challenges. Immobilizing NMNPs on substrates often reduces their catalytic activity due to hindered diffusion and decreased surface area. This study presents a novel approach using silver (N-Isopropylacrylamide Co methyl acrylic acid) (Ag@PNM) nanoparticles, characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering transmission (DLS), transmission electron microscopy (TEM) and UV–visible spectroscopy. A catalytic membrane with silver nanoparticles (Ag NPs) embedded in a three-dimensional (3D) network of hybrid microgels was fabricated. The microgels are filtered into a microporous membrane and expanded to secure the Ag NPs, enhancing catalytic efficiency for 4-nitrophenol reduction through improved mass transfer and exposure of the nanoparticles. The membrane shows high stability and performance, with a turnover frequency of 77.5 h⁻¹ and an apparent rate constant (k_app) of 0.15 s⁻¹. Additionally, the PES/Ag@PNM membrane demonstrated effective reduction of 4-nitrophenol. The straightforward synthesis and stability of this approach make it a promising and cost-effective solution for industrial applications.

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In this study, the effect of hexagonal boron nitride (hBN) addition at different weight ratios to thermoplastic polyester elastomer (TPEE) reinforced with three different fiber types, namely carbon fiber (CF), glass fiber (GF) and basalt fiber (BF), on the mechanical, tribological and thermal properties of the composites was investigated. Adhesive wear test for tribological analysis, tensile and three-point bending tests for mechanical analysis, differential scanning calorimetry and thermogravimetric analyses for thermal investigation and scanning electron microscopy analysis for morphological evaluation were applied. The results showed that the addition of hBN to fiber-reinforced TPEE composites, regardless of the fiber type, and the increasing weight ratio of hBN improved the wear, mechanical and thermal properties of the composites. However, when comparing the synergistic effect of hBN when used simultaneously with fiber reinforcement on the basis of fiber type, CF was found to outperform GF and BF fiber types and hybrid reinforced composites containing 10 wt% hBN and CF to exhibit superior tribological, mechanical and thermal properties. It is also concluded that BF performs at a comparable level to GF and therefore can be used instead of GF in some applications.

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In this study, Felodipine-loaded nanoparticles were prepared using the nanoprecipitation method, with quince seed mucilage serving as the polymer matrix and Tween 80 utilized as a stabilizing agent. The nanoparticles were thoroughly characterized using a range of analytical techniques, including dynamic light scattering (DLS), zeta potential measurement, Fourier-transform infrared spectroscopy (FTIR), thermal analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Felodipine nanoparticles displayed an amorphous structure, with formulation FEL 4 achieving the highest entrapment efficiency of 67.68%. This formulation also had an average particle size of 675 ± 2.04 nm and a zeta potential of − 31.7 ± 1.34 mV. Saturation solubility tests revealed a significant enhancement in water solubility for the nanoparticles compared to pure Felodipine. Additionally, in vitro drug release studies demonstrated a sustained release profile over 24 h in phosphate buffer. Acute oral toxicity evaluations confirmed that the Felodipine nanoparticles did not exhibit any signs of toxicity. Overall, this study showed the successful fabrication of quince seed mucilage-based Felodipine-loaded nanoparticles as a promising approach to enhance solubility and achieve sustained drug release, with no evident toxicity.

In this study, microcrystalline cellulose was prepared from the post-harvest banana stem by using a homogeneous Fenton system (MCC-F) and used as an adsorbent for removing Cu²⁺ and Ca²⁺. Simultaneously, the reference materials of MCC-H and MCC-N were also prepared by using H₂O₂ and NaIO₄ solutions, respectively. Characteristics of the prepared materials were determined by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, the point of zero charge, and the content of aldehyde and carboxyl functional groups. In batch Cu²⁺ and Ca²⁺ adsorption tests, an optimal pH value of 7.0 was found for both target metal ions while 30 min and 75 min were chosen as the optimal contact time for Cu²⁺ and Ca²⁺ ions, respectively. The best fit was obtained with the pseudo-second-order kinetic model. Langmuir, Freundlich, and D–R isotherm models were applied to calculate adsorption data. Thermodynamic results suggest that the adsorption of metal ions by MCC-F is an exothermic and spontaneous process. Therefore, MCC-F is a high-potential and promising material for water and wastewater treatment.

The widespread availability of banana peels makes them an excellent resource for bio-fillers in developing environmentally conscious and biodegradable composites, serving as substitutes for plastic and synthetic waste. This study focuses on using banana peel waste as a bio-filler to produce lighter and cheaper materials. The extracted banana peels were subjected to alkali treatment to improve interfacial interaction, and their crystalline performance, functional categories, and morphological studies were examined using XRD, FTIR, and SEM techniques. Composite samples were fabricated with varying bio-filler ratios (0.0, 2.5, 5.0, 7.5, and 10%) to examine their thermo-mechanical and tribological attributes. The inclusion of banana peel in the epoxy matrix at up to 5% significantly enhanced mechanical performance, while 7.5% composites demonstrated higher thermal endurance with a degradation temperature of 395 °C and reduced water retention. Frictional wear of the specimens was assessed by varying sliding speeds under different loads, with the highest coefficient of friction and temperature observed under a 30 N force for BPC-10.0 specimens. This research innovatively uses banana peel powder (approx. 65 µm) to create polymeric composites, addressing the need for sustainable materials with higher specific modulus and strength compared to conventional substances. The study uniquely evaluates the physical, mechanical, structural, and tribological efficiency of raw and processed banana peel particles, with chemical modifications improving crystallinity and interfacial bonding. This comprehensive approach provides vital insights for developing sustainable alternatives to reduce plastic usage.

Utilizing the solution casting technique, polymer nanocomposites (PNCs) films including polyethylene oxide and chitosan (PEO/CS) doped with titanium dioxide nanoparticles (TiO₂ NPs) as nanoceramic were successfully synthesized. The study investigated how varying TiO₂ nanoparticle concentrations influenced the structural, optical properties, and antibacterial activity of the polymeric matrix. XRD patterns revealed an increase in the amorphous nature of the polymer blend as the content of TiO₂ NPs inside the PEO/CS blend grew. The FT-IR analysis confirmed the interaction between TiO₂ NPs and the PEO/CS blend. This confirmation is attributed to the observed vibrational changes upon the incorporation of TiO₂ dopant into the polymer matrix. The UV–visible spectrum aided in the determination of optical energy band gaps (both direct and indirect), showing reductions in both E_gd and E_gin with higher TiO₂ concentrations. SEM highlighted the partial compatibility between PEO/CS and TiO₂, while transmission electron microscopy depicted spherical TiO₂ NPs with diameters ranging from approximately 9 to 25 nm. Antimicrobial assessments indicated heightened efficacy in all nanocomposite samples compared to the pure PEO/CS composite, with a linear correlation to the quantity of TiO₂ nanoparticles present. These findings strongly suggest the potential of these nanocomposites for food packaging applications.

This work examines the effects of varying weight percentages (0.1, 0.3, and 0.5 wt%) of pristine and functionalized graphene (–COOH, –OH, and –NH₂) on the compression and impact strength of carbon fiber-reinforced polymer (CFRP) composite laminates. The laminates were fabricated in two different stacking sequences of carbon fiber in composite laminates, i.e., 0/90° and 0/90/ ± 45° by hand layup technique. Experimental results showed that the inclusion of graphene in epoxy matrix enhances the compressive strength and impact characteristics, namely impact force, displacement, energy profile, and damage behavior of CFRP laminates. Moreover, the orientation of carbon fiber layers in laminates affects the internal damage behavior of specimens and the delamination between fiber layers. The maximum improvements of 38.65 and 76.82% are noticed in the compressive strengths of 0/90° and 0/90/ ± 45° stacked laminates with the reinforcement of 0.1 wt% of pristine and 0.3 wt% of –COOH functionalized graphene to epoxy, respectively. In summary, the test results have shown that using graphene as a reinforcing filler can significantly improve the impact performance of CFRP composites.

This study aims to investigate the mechanical, thermal, morphological, and characterization properties of a polymer composite composed of water hyacinth plant fibres. In order to improve the mechanical properties of the composite specimens, a new powder derived from the moringa plant was used for the first time as a filler material in the water hyacinth plant-reinforced polymer composites. In this study, composite specimens were prepared using a hot compression moulding machine. The weight percentage of moringa resin filler powder and hyacinth fibre was varied during the process from 2.5 to 7.5% and 15 to 35%. The resulting tensile strength ranged from 18.24 MPa to 32.14 MPa, flexural strength ranged from 38.64 to 56.32 MPa, impact strength ranged from 1 to 3.75 J, and hardness ranged from 66 to 98 Shore D hardness. The composite sample containing 5% moringa filler powder and 30% WH fibre content achieved high mechanical strength, maximum decomposition temperatures, and high crystallinity percentages. It exhibited 11–13% higher strength compared to the other samples. Absorption studies showed weight gains of 3.42% and 4.45% for water and chemical absorption, respectively. The fracture surfaces of the composite specimens were analysed using the SEM technique. The fabricated composites could be useful for particle board and medium density fibre board applications.

The current study dealt with development of nonwoven mulch mat from textile waste and its evaluation in the field for chilli crop. Six needle-punched nonwoven mulches were developed from textile mill waste comprising of cotton, polyester and acrylic in two different ratios. All ratios were varied with three different areal density ratios i.e. 200, 300 and 400 g/m² with 4-, 3.5- and 3-mm thickness, respectively. The mulch mats were characterised for their physicomechanical properties such as tensile strength, elongation, air permeability, thermal insulation and resistance to sunlight degradation. Further, the developed mulches were analysed for its performance in the field on the hybrid variety of chilli CH-27. Parameters, including soil moisture content, soil temperature, weed suppression, yield and soil degradation were investigated through field tests, against a polyethylene mulch, paddy straw and without mulch. The experimental results revealed that the developed nonwoven mulches worked as buffer media between the atmosphere and soil surface and influenced the temperature of soil. These mulches performed better to maintain the soil temperature than the paddy straw and polyethylene mulch. On the basis of plant grown and crop yield, the best much performance was observed with cotton: polyester: acrylic (70:20:10) with 200 g/m².