Macromolecular Research最新文献

This study deals with employing central composite design (CCD) as a design of experiment (DoE) tool for finding an appropriate model representing the evenness of polyester fully drawn yarn (FDY). Main effects of parameters like melt temperature, quenching air velocity, winding speed, draw ratio, and the position of the bobbin on the coefficient of variation (CV) of the FDY were examined. The interactions between significant factors were detected by the analysis of variance. CCD model showed that the quenching air velocity has no significant effects on the CV values. The special effects of the winding speed and melt temperature are higher than that of draw ratio and the position of the bobbin. Final model predicted the minimum CV values of 1.72–1.78% at 15 melt spinning conditions. Optimal CV value (1.72%) was achieved at the melt temperature of 283.8 °C, quenching air velocity of 41.0 m/s, winding speed of 4391.7 m/min, draw ratio of 2.89, and the position of 0°. It was also revealed that the average tensile strength of the PET filament yarns decreases from 44.73 ± 1.13 to 40.50 ± 0.81 cN/tex as the unevenness increases from 1.8 to 3.0. These results indicated that the CCD is well capable of analyzing, modeling, and optimizing the evenness of the PET filament yarns.

Graphical abstract

A lay out of melt spinning process and the variation of CV versus quenching speed and temperature.

TiO₂ is one of the most important materials in modern industrial societies because of its outstanding chemical and electrical properties. Many properties of TiO₂, including its charge transport behaviors, grain boundaries, surface-to-volume ratio, and contact with surrounding systems, are strongly influenced by its nanoscale architecture. In this regard, TiO₂ nanotubes produced by anodization have received extensive attention as a promising TiO₂ architecture because of their unique one-dimensional configuration that includes well-defined nanostructures with a vertical orientation. These architectural features enable efficient charge transport along the axial direction. However, early anodized TiO₂ nanotubes suffered several drawbacks including limited substrate and singly open-ended nanostructure restrict their further applications. To address these challenges, researchers have developed advanced TiO₂ nanotubes, and several TiO₂ nanotube structures, including freestanding membranes, doubly open-ended nanotubes, and hierarchical structures, have been reported, and these TiO₂ nanotubes have exhibited enhanced performance in various applications. In this article, we review recent advances in the structural developments of anodized TiO₂ nanotubes and the applications of these materials in the field of solar energy.

Graphical abstract

Schematic diagram of the characteristics and applications of TiO₂ nanotubes.

In this study, amino functionalized cellulose nanocrystals–polyethersulfone nanocomposite membrane (A-CNC/PES) based on agricultural waste was used for the removal of diazinon (DZ) from aqueous solution. The fabricated membrane has been characterized via attenuated total reflectance-Fourier transform infrared (ATR-FTIR), scanning electron microscopy (SEM), dispersive X-ray spectrometer (EDX), X-ray diffractometer (XRD), thermal gravimetric analysis (TGA), water contact angel (WCA), porosity, and mean pore radius. The effect of variables, such as initial DZ concentration, pH, and A-CNC content, on the membrane performance was optimized using response surface methodology (RSM) through central composite design (CCD). The results indicated that the additive had the most significant effect on the hydrophilicity improvement, reducing surface roughness, and reducing fouling. The highest removal efficiency of A-CNC/PES membrane for DZ was about 99.3% (at A-CNC: 0.2 wt%), and more than three-fold water flux improvement (27.3 versus 8.3 kg/m².h for unmodified membrane) was attained. The results of antifouling test confirmed that the A-CNC/PES membranes had a high-flux recovery (FRR: 90.05%). This study may provide promising insights for the development of next generation of agricultural waste-based nanocomposite membrane in the water and wastewater treatment.

Graphical abstract

Highly efficient removal of diazinon pesticide from aqueous solutions by using grape branch-derived CNCs-PES nanocomposite membrane.

Interfacial thermal resistance is crucial for determining the thermal conductivity of composites. Existing studies have explored hybrid filler systems and surface modification of alumina (Al₂O₃) particles for enhancing the thermal conductivities of polymer composites. In this study, highly acidic Al₂O₃ fillers were fabricated by modifying the raw Al₂O₃ surface using citric acid and glucose; the modified Al₂O₃ infiltrated an uncured epoxy adhesive at a concentration of 80 wt.%. The measured thermal conductivities of composites were up to 19.4% and 35.9% higher in glucose-filled and citric acid-filled Al₂O₃, respectively, compared with the raw Al₂O₃ at 25 °C. The experimental analysis and theoretical calculations revealed that the polar functionality on the surface facilitated hydrogen bonding between the filler and epoxy resin, which reduced the interfacial thermal resistance in the composite; this effect was the highest for the carboxyl group. To demonstrate the practical application of the modification technique, the exothermic performance test was conducted and indicated that a light-emitting diode lamp incorporating the citric acid filler-based composite exhibited excellent heat management performance compared to the raw Al₂O₃-applied composite.

Graphical abstract

Acidic Al₂O₃ fillers were prepared to reduce interfacial thermal resistance through hydrogen bonding, resulting in a modified particle-filled epoxy composite with enhanced thermal conductivity. The light-emitting diode (LED) lamp, utilizing epoxy adhesive with these modified Al₂O₃ fillers, demonstrated excellent heat dissipation capabilities

Harmful heavy metals have a significant effect on the toxicity of wastewater due to their non-biodegradability; hence, they will harm living things. Graphene oxide has been studied in recent research to remove these heavy metals. This study was carried out to determine the characterization of graphene oxide-based hyperbranched polymers (GO-MHBP) and their batch experiments on removing heavy metals (Cr³⁺ and Hg²⁺). The surface of the graphene oxide particles was modified by 3-(aminopropyl) triethoxysilane, and then hyperbranched polymers were fabricated by incorporating 3,5-diaminobenzoic acid and maleic anhydride. The synthesized polymers were characterized physically and morphologically using FT-IR, FE-SEM, EDX, and TGA techniques. Moreover, they were assessed in terms of adsorption capacity to remove pollutants of Cr³⁺ and Hg²⁺. To that end, the effect of pH, adsorbent amount, contact time, and initial concentrations of metal ions was evaluated. Furthermore, the adsorption kinetics and isothermal behavior were investigated for the adsorption efficiency of GO-MHBP nanocomposite. The adsorption process was consistent with the second-order kinetic model and the Langmuir isotherm model. Eventually, the GO-MHBP could serve as promising adsorbents for potential application in the removal of Cr³⁺ and Hg²⁺ from wastewater.

Graphical abstract

Graphene oxide-based hyperbranched polymers provided an effective adsorbent system for heavy metal removal. These nanocomposites are significant for the remediation and removal of Cr³⁺ and Hg²⁺ ions from wastewater due to their simple synthesis method and low cost

The goal of present work is to create a polymer base for compounds, binders for materials with different fillers and adhesives. The article presents the results of studies of the physical and mechanical characteristics of urethane-containing elastomers based on epoxy urethane oligomers. The reaction proceeded in two stages and included the formation of oligodiisocyanate. Based on them, elastomers with urethane-hydroxyl hard segments were synthesized. Methyl nadic anhydride and an oligodiendiol with terminal carboxyl groups were used as hardeners. The deformation-strength properties of elastomers, as well as the strength of the adhesive joints for aluminum and steel, were studied. Using an oligomer with carboxyl groups as a hardener lowers the glass transition temperature of elastomers and improves their deformation characteristics. The glass transition temperature of the samples was determined using a differential scanning calorimeter. The physical and mechanical tensile characteristics of the obtained materials were determined on a universal testing machine. Elastomers cured with an oligomer containing carboxyl groups can be used as a polymer base for compounds and binders for materials with different kinds of fillers due to their low modulus and high deformation properties. Elastomers cured with methyl nadic anhydride may find use as adhesives.

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The goal of this study is to determine the effect of varying the volume fraction of a novel ABS–rubber seed husk cellulose 3D-printed honeycomb core on the mechanical, drop load impact, fatigue, and thermal behavior of a sunn hemp polyester skin composite. The cellulose/ABS-tailored filaments were created using a screw extruder and the composites were manufactured using compression molding. The results of the tests showed that the tensile strength, flexural strength, tensile modulus, flexural modulus, and Izod impact were all enhanced by the addition of cellulose and the sunn hemp fiber. Moreover, adding 4.0 phr of cellulose to the ABS matrix increased its tensile strength by 141 MPa, flexural strength by 173 MPa, tensile modulus by 4.9 GPa, flexural modulus by 6.1 GPa, and impact toughness by 5.5 J. Similarly, under 25, 50, and 70% of ultimate stress loading conditions, and the fatigue cycles of the composite RSC5 with cellulose content of 4.0 phr reached up to 26,897, 23,899, and 21,559. However, composite with 2.0 phr of cellulose produced significant energy absorption of 12.4 J in the drop load impact toughness. Similarly, the mass-loss stability of composite RSC5 improved with 4 phr of cellulose. The final decomposition temperature was recorded at a maximum of 532 °C, which is a significant improvement on comparison with other composites. Finally, SEM fractography proves that the ABS core adheres better to the polyester resin and the fibers are well adhered to the matrix. In engineering applications, where lightweight composite panels and boards are required, these high-performance and high-thickness core–skin composites could be utilized.

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As a typical endocrine disrupter, bisphenol A (BPA) in the environment could damage the reproductive and endocrine system of humans and mammals. Hence, the precise removal of BPA from the environment becomes increasingly urgent. In this work, we employ Pickering emulsion polymerization to prepare the molecularly imprinted polymer (MIP) microspheres containing specific binding sites for the precise recognition of BPA through the non-covalent molecular imprinting strategy. In the process of polymerization, TiO₂ nanoparticles are used as the sole emulsifier to build the Pickering oil/water emulsion system followed by the radical polymerization. The template molecules of BPA could be eluted from the polymer microspheres by continuous Soxhlet extraction. The obtained MIP microspheres were characterized with the help of optical microscope and field emission scanning electron microscope, respectively. The MIP microspheres present regularly spherical structures with a relative broad size distribution. The chemical structure and thermal stability of MIP and non-imprinted polymer (NIPs) microspheres also were investigated by Fourier transform infrared spectroscopy and thermogravimetry, respectively. The formation of specific imprinted sites on the MIPs was validated through a batch of rebinding experiments, including the binding kinetics, binding isotherm and selective experiment. Moreover, the obtained MIP microspheres could be regenerated and recycled at least five cycles without significant loss of binding capacity. The MIP microspheres would have broad application prospects in the environmental and analytical field.

Graphical abstract

Schematic illustration for the preparation of MIPs microspheres via Pickering emulsion polymerization

In this study, hollow nanospheres of titanium dioxide (TiO₂) are prepared and utilized as potential nucleating agents in supercritical carbon dioxide (scCO₂) foaming process of thermoplastic polyurethanes (TPUs) at different foaming temperatures and saturation pressures. To produce the hollow nanospheres of titanium dioxide (TiO₂), well-defined spheres of polystyrene (PS) with a diameter of about 300 nm are first synthesized as templates using surfactant-free emulsion polymerization. A layer of titanium tetraisopropoxide (TTIP) is then uniformly coated on the PS spheres followed by calcination in a furnace to convert the titania layer to the titanium oxide layer. Hollow nanospheres of titanium dioxide with a well-defined morphology are prepared by calcination at high temperatures, as the PS spheres completely decompose. Interestingly, highly porous structures, which give rise to high surface area for trapping scCO₂, are generated on the surface of the TiO₂ nanoparticles during the thermal treatment. The dispersion of TiO₂ nanospheres in the TPU matrix is successful, serving as heterogeneous nucleating agents that influence the cell density and morphology of the extended TPU in the foaming process.

Graphical abstract

In this study, hollow nanospheres of titanium dioxide (TiO₂) with unique porous surface are prepared and utilized as potential nucleating agents in supercritical carbon dioxide (scCO₂) foaming process of thermoplastic polyurethanes (TPUs) to control various foaming parameters including foaming ratio, cell size, cell density etc.