Band 44, Heft 6

The interlaminar structure and dynamic mechanical properties of Tectona grandis fiber (TGF), polypropylene fiber (PPF), and carbon nanotube (CNT) nano composite were investigated in the current study. In order to improve the mechanical characteristics and microstructure, the present investigations used T. grandis fiber and polypropylene fiber (inorganic–organic) materials mixed with nano composite and epoxy resin. Strong bonding strength and high wear resistance were created by the silane characteristics during the coating process for the outer surface layers. Since CNT nanomaterials were directly reflected onto the outer surface, the microstructure analyses amply demonstrated that hexagonal lattice structure and crystallisation development were detected in the inner surface layer. In order to increase high stiffness and bonding strength, storage modulus and loss modulus values were applied to all composite materials, and the TGF/PPF/CNT composite materials’ hardness value was developed at 112 HV. The tensile strength of TG/PP composite was 46.7 MPa, while that of TGF/PPF/CNT composite was 57.4 MPa. Studies on wear resistance showed unequivocally that the TGF/PPF/CNT composite reduced wear and friction.

Polyoxymethylene (POM) which shows good mechanical properties has a wide range of application in engineering. In this work, the nanoscale simulation method of molecular dynamics (MD) is used to make a more systematic simulation and calculation of the model of the resin material POM. With the application of software, the influence of friction depth, temperature, and sliding velocity on the frictional properties of POM was studied. The main conclusions are as follows: (1) In the range of 300 K–400 K, the temperature has little influence on the friction coefficient, but the fluctuation of friction force becomes larger as the temperature becomes larger. (2) When the friction depth increases, the plowing phenomenon and the accumulation of debris become more obvious and plastic deformation of POM increases. (3) When the friction velocity is changed, it is found that there is not much correlation between friction force and friction velocity, but as the friction velocity decrease, the friction force also decrease to a smaller extent. (4) The friction force will experience a growth period, and its value gradually stabilizes with some fluctuations, which are mainly caused by the atomic thermal motion, the effect of abrasive chip accumulation, and the release of stress energy caused by deformation.

In this approach, nanocomposites of PVDF/PMMA/CTAMag films have been successfully synthesized. Modified Maghnite was used as inorganic reinforcement. In this study, nanocomposite polymers were developed based on a mixed matrix of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) of composition (80/20 w/w) in dispersion containing 0, 1, 3, 5 and 7 wt % fillers of organomodified montmorillonite nanoclay (CTAMag) in the melt state. The results obtained by scanning electron microscopy (SEM), XRD traces and FTIR spectra highlighted the homogeneous flexible character of the PVDF/PMMA/CTAMag films and their intercalated and intercalated/exfoliated surface morphology, in addition to the presence of PVDF α , β and γ phase crystallites in these complex films. The increased presence of the modified clay in the host matrix of the PVDF/PMMA blend significantly influenced the melting temperature and the degree of crystallinity of the PVDF crystallites. The scattering of the dielectric spectra, which covers a wide range of frequencies from 20 Hz to 1 GHz, indicates the presence of the phenomenon of interfacial polarization associated with the dielectric capacitance complex at lower frequencies in these composites at 27 °C. The mechanical properties of these composites were evaluated as a function of the load and the mixed matrix of these composites.

Conductive polymer-based adsorbents have showed excellent heavy metal ion removing capabilities. Crosslinking modification is one of the feasible methods to further improve their properties. To make use of the advantages of monomer precursor method over the polymer precursor method in forming dense interpenetrating networks, and then optimizing the surface structure of materials and providing more adsorption sites, the mesoporous cross-linked poly- o -phenylenediamine (M-CR-P o PD) prepared by using the former one and used in removing Cu 2+ from aqueous solution. The FTIR results showed that the monomer was successfully crosslinked and polymerized. The loosely packed target product with a hierarchical pore structure distribution was successfully formed. The maximum adsorption capacity of 105.18 mg g −1 was obtained at 25 °C after 3 h of adsorption when M-CR-P o PD prepared at the reaction time of 6 h using anhydrous ethanol as solvent and trimethylolpropane-tris(3-aziridinyl) propionate as crosslinking agent. This value reached the optimum Cu 2+ removal capability of reported P o PD-based adsorbents. According to EDX, FTIR, and XPS data before and after adsorption, the possible adsorption mechanism based on the cation-π interaction and the formation of Cu–N bonds was proposed. These results could help develop more effective conductive polymer-based adsorbents to remove Cu 2+ from wastewater.

Manganese dioxide (MnO 2 ) nanoparticles were modified by graphitic carbon nitride (GCN) and polylpyrrole (Ppy) to enhance their electrochemical performance. The surface influence, crystalline structure, and electrochemical performance of the Ppy/GCN/MnO 2 material were characterized and compared with those of pristine MnO 2 . It is found that surface modification can improve the structural stability of MnO 2 without decreasing its available specific capacitance. The electrochemical properties of synthesized Ppy/GCN/MnO 2 electrode were evaluated using cyclic voltammetry (CV) and AC impedance techniques in 5 M KOH electrolyte. Specific capacitances of 486, 815, 921, and 1377 F/g were obtained for MnO 2 , Ppy/MnO 2 , GCN/MnO 2 , and Ppy/GCN/MnO 2 , respectively, at 5 A/g. This improvement is attributed to the synergistic effect of GCN and Ppy in the Ppy/GCN/MnO 2 electrode material. The Ppy/GCN/MnO 2 electrode in KOH has average specific energy and specific power densities of 172 Wh kg −1 and 2065 W kg −1 , respectively. Only 2 % of the capacitance’s initial value is lost after 10,000 cycles. The resulting Ppy/GCN/MnO 2 nanocomposite had very stable and porous layered structures. This work demonstrates that Ppy/GCN/MnO 2 nanomaterials exhibit good structural stability and electrochemical performance and are good materials for supercapacitor applications.

Despite the widespread attention garnered by self-healing hydrogels in various fields, achieving a balance between high mechanical strength and self-healing capability remains a challenge. Particularly, the addition of fillers in the fabrication of spray-coated waterproof materials hinders the movement of molecular chains. Simultaneously, the self-repair of metal ions is hindered by issues such as a prolonged required time and low repair rate. Therefore, we introduce a polyvinyl alcohol (PVA) solution subjected to freeze–thaw cycles into the acrylic acid magnesium/calcium hydrogel system, creating a self-healing hydrogel with an interpenetrating polymer network (IPN). Due to the abundance of hydroxyl groups on the PVA molecular chains, during the freezing process, some PVA chains form microcrystals that do not dissolve upon thawing at room temperature. These microcrystals act as cross-linking points, connecting PVA chains into a 3D network. Consequently, the hydrogel, under the dual effects of hydrogen bonds and coordination bonds, exhibits excellent mechanical properties and the ability to self-heal at room temperature. Furthermore, by adjusting the concentration of the PVA solution, the mechanical properties and healing ability of the hydrogel can be tailored to meet various construction requirements.

In this study, ramie fiber was employed to prepare cellulose triacetate (CTA) films. Subsequently, the photodegradation behaviors without photosensitizers of CTA films were carried out in photodegradation chambers at 40 °C. Additionally, the photodegradation procedure of films was assessed by the attenuated total reflection infrared (ATR-IR), 1 H nuclear magnetic resonance ( 1 H NMR), scanning electron microscope (SEM), thermal properties, degree of substitution (DS), and tensile strength. The research consequences indicated that the mechanical strength of the CTA films was decreased significantly after ultraviolet (UV) irradiation for 300 h. However, the DS of the films is almost invariable when they are exposed to UV irradiation. Meanwhile, the suggested mechanism for photodegradation of CTA was also exhibited in this paper. This study provides a mild and potential pre-treatment approach for the biodegradation of LCD used waste CTA films.