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In this work, a novel three-dimensional (3D) hollow nickel-cobalt layered double hydroxide (NiCo-LDH) was synthesized using zeolitic imidazole framework-67 (ZIF-67) as a template, and then utilized to functionalize molybdenum disulfide (NiCo-LDH/MoS2) via electrostatic force. Flame retardant thermoplastic polyurethane (TPU) composites were prepared...
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... release rate (HRR) is an important indicator to describe the fire hazard of polymers and can predict the behavior of polymers under real combustion conditions [30]. The HRR results for pure TPU and TPU composites are given in Figure 6 and Table 2. In Figure 6, pure TPU burns fiercely after being ignited and has the highest peak heat release rate (PHRR) of 1135 kW/m 2 . ...
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... HRR results for pure TPU and TPU composites are given in Figure 6 and Table 2. In Figure 6, pure TPU burns fiercely after being ignited and has the highest peak heat release rate (PHRR) of 1135 kW/m 2 . The addition of 2 wt% NiCo-LDH and MoS 2 nanosheets slightly decreases the PHRR of TPU composites to 804 kW/m 2 and 734 kW/m 2 , respectively, indicating that MoS 2 and NiCo-LDH nanosheets can inhibit the heat release of TPU composites and improve the flame retardancy of TPU composites to a certain extent. ...
Context 3
... the other hand, two-dimensional MoS 2 nanosheets have nano-barrier effect, which can hinder the release of volatile products including hydrocarbons, so that less volatile products form fuel into the combustion zone, thereby reducing the heat release rate [32]. It is not difficult to see from Figure 6 that the ignition time of TPU composites is longer than that of pure TPU, which is related to the decomposition of MoS 2 ignition time of TPU composites, which is attributed to the early decomposition of MoS2 nanosheets or NiCo-LDH/MoS2. Figure 7 exhibits the total heat release (THR) curves of pure TPU and TPU composites. Pure TPU has the highest THR value of 118.8 MJ/m 2 . ...
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Zeolitic imidazolate framework-67 crystals (ZIF-67) anchored molybdenum disulfide nanosheets (MS) have been synthesized via a hydrothermal approach followed by a simple chemical method. MS concentration has been varied to investigate its impact on the electrochemical efficiency within the electrode nanocomposite. The shiny spot of this composite is...
Citations
... [9,10] Studies have shown that LDH can also work with other flame retardant effect materials to improve the fire safety performance of composites, for instance graphene [11] and MoS 2 . [12] Qian et al. [13] investigated the flame retardant properties of MoS 2 and LDH by hydrothermal synthesis and showed that the nanomaterial hybridization not only made LDH more dispersed in the collective TPU material, but also the total heat released during combustion and the amount of smoke produced are greatly reduced. Discovered by Gogotsi et al. in 2011, MXene is a twodimensional material that has attracted much attention for its excellent properties and it has the advantages of high specific surface area, excellent thermal stability, and good catalytic performance, hence MXene also has great potential for flame retardant applications. ...
... It can be seen from the XRD patterns of the TPU/CoMn-LDH composites that the characteristic peaks of Co 2 O 3 spinel appear at around 27.5°, 31.1°, 38.4°, CoO spinel at around 36.5°, 42.2°, [13,24] [41] indicating that the elements Co and Mn were oxidised to form metal oxides during the combustion process. In the XRD spectra of TPU/MXene, the characteristic peaks of rutile TiO 2 formed by oxidation are located at 27 36.0°, ...
In recent years, MXene 2D materials have shown good performance in enhancing the flame retardant properties of composite materials, but it is still tricky to improve the compatibility with the polymer matrix. This work explores a simple method for the synthesis of MXene based nanohybrids (CoMn‐LDH@MXene) by hydrothermal synthesis using MXene and layered double hydroxides (CoMn‐LDH) to construct a flame retardant system with excellent performance. The results show that the MXene nanosheets are less built up and more dispersed in the TPU collective due to the inclusion of LDH, giving the TPU composites excellent flame retardant and smoke suppressant properties. Compared to TPU without flame retardant, TPU composites with 2 wt% CoMn‐LDH@MXene reduced PHRR by 33.7 % and THR by 28.7 %. The TPU/2wt %CoMn‐LDH@MXene composites also showed better flame and smoke suppression performance, PSPR, TSP, PCO and PCO2 were reduced by 44.4 %, 22.7 %, 37.7 % and 27.2 % respectively, the production of Hydrocarbons and HCN were also reduced. Barrier effect of transition metal oxide catalysed carbon layer formation, combustion blocking effect of hybrid material nanosheets, cooling effect of water vapour from thermal decomposition of LDH and the gas phase dilution effect are the main reasons for the increased fire safety of TPU composites.
... The nitrogen oxides combine with water in the air and are eventually converted into nitrates. Large particles of nitrate settle in the charcoal [62,63]. During the degradation process, cobalt ions undergo an elemental valence change that can catalytically enhance the heat capacity of residual carbon and prevent heat delivery to the substrate, which protects the composite from burning. ...
... In another similar work, a three-dimensional (3-D) hollow nickel-cobalt LDH (NiCo-LDH) underwent synthesization via zeolitic imidazole framework-67 (ZIF-67) acting as template, and further utilized in functionalizing molybdenum disulfide (NiCo@LDH@MoS 2 ) through electrostatically inclined force. [50] F-R TPU nanocomposites were fabricated via melt extruding technique. In comparison with pristine TPU, NiCo-LDH@MoS 2 reinforced TPU nanocomposites demonstrated decreasing values of 30.9% and 55.7% for PHRR and peak smoke production rate (PSPR), respectively. ...
... In comparison with pristine TPU, NiCo-LDH@MoS 2 reinforced TPU nanocomposites demonstrated decreasing values of 30.9% and 55.7% for PHRR and peak smoke production rate (PSPR), respectively. [50] Figure 25. A. SPR graph of pristine TPU and TPU nanocomposites. B. TSP graphs of pristine TPU and TPU nanocomposites (a, b). ...
... F-R was ascribed to the catalytically affiliated carbonization influence and the diluting influence of NiCo@LDH, as well as the barricading influence of MoS 2 nanosheets which inculcated TPU nanocomposites with outstanding F-R and toxic gas inhibiting capacity. [50] Figure 28 A presents the fabrication . TG (a, c) and DTG (b, d) curves of TPU and TPU nanocomposites. ...
... However, some problems faced by 2D nanomaterials, such as the interlayer van der Waals forces, make them prone to forming agglomerates, and smooth and inert surfaces are not conducive to their dispersion in the matrix, which seriously affect the comprehensive properties of the composite materials. 28 LDHs systems can be used to improve the compatibility of twodimensional materials with a polymer matrix due to their rough surface and abundance of oxygen-containing groups. Generally, ZIF-67 is firstly anchored on 2D nanomaterials and then transferred into NiCo-LDH. ...
... In addition, copper ions can cause the catalytic conversion of CO to CO 2 via the Mars-van Krevelen mechanism to diminish the CO emission. 28,58 To improve the compatibility of LDHs to enhance their fire safety in epoxy composites, Hu et al. synthesized hollow dodecahedral NiCo-LDH@PZS with ZIF-67 as a precursor and a sacrificial template, and polyphosphazene (PZS) as an interface compatibilizer and flame retardant. 32 PZS has excellent free radical trapping capacity as well as char formation effect, and synergies with NiCo-LDH significantly inhibit the smoke toxicity generated during the combustion process of EP composites and promote the formation of graphitized residual char. ...
The physicochemical properties of metal–organic frameworks (MOFs) are closely dependent on the topology, pore characteristics, and chemical composition, which can be tuned through targeted design. Relative to direct synthesis, the post-synthesis methods of MOFs, including ion exchange, ligand replacement as well as destruction, provide a significant increase in their application range and potential. A method based on the coordination bond cleavage of MOFs has been proved to be very effective in modulating the structure and was evaluated for its application in the flame retardant field. Herein, the construction of peculiar MOF structures is categorized based on flame-retardant features through the cleavage of coordination bonds at the molecular level, and the corresponding MOFs exhibit superior flame-retardant and smoke-suppressing properties. Different approaches are highlighted to achieve coordination bond breaking to modulate MOFs properties, involving chemical composition, topology, and pore structure. This review systematically summarizes and generalizes the direct construction of high-efficiency MOF-based flame retardants based on the structure–activity relationship and their further functionalization through coordination bond cleavage, as well as the associated challenges and prospects. It is also hoped that this work will quickly guide researchers through the field and inspire their next studies.
Keywords: Metal–organic frameworks; Fire retardancy; Molecular cleavage; Coordination bond; Flame retardant mechanism.
... [72] Furthermore, strong adherence between the nanofiller and polymeric matrix induces reduced mobility of polymeric chains followed by minimization of the rate of decomposition. [73] Therefore, utilizing any route capable of incrementing the strength of the interactivity between the nanocomposite components is capable of improving its thermal stability. ...
A pertinent concept emerging from nanocomposites/nanoarchitectures is the sharp increment at the
interfacial region existing between nanoreinforcements and the polymeric matrices on reduction of at
least a single size of the fillers to the nanometric scale. The inclusion of minimal levels of nanoparticulates
within polymeric melts has been established to notably enhance the properties of these polymeric
nanoarchitectures (PNC) mechanically, thermally, electrically, and optically, in comparison with the
unreinforced constituents. The enhancement in material features emanates from the interface created
between the nanoreinforcement and bulk polymeric matrices, wherein the inherent chain dynamics
varies when compared with the pristine material. Hence, the spatially arranged or nanoreinforcements
organization influences the three-dimensional architecture of the interface, resulting in improved
control of macroscopically affiliated features. From this perspective, this paper will elucidate on
interfacial engineering and controlling in space of confinement as well as the linkage between the
interface and the macroscopic features of polymeric nanoarchitectures (PNC). Furthermore, the influence
of interfacial interactions on mechanical, thermal, electrical, and flame retardant properties of PNC
is critically elucidated.
Cotton fabric composites were designed to be protected by fire safe thermoplastic polyurethane (TPU) composites for developing electromagnetic interference (EMI) shielding polymer composites with superior mechanical properties. Herein, the as-prepared MXene was coated onto the fiber surface of cotton and then thermally compressed with TPU composites, which were filled with the sodium dodecyl sulfate modified layered double hydroxides functionalized the short carbon fiber hybrids through melt blending method. Then, a series of highly fire safe cotton/TPU hierarchical composites were constructed by a designed thermal compression technique. For instance, the obtained cotton/TPU hierarchical sample showed greatly reduced peak of heat release rate, peak of carbon monoxide production rate and peak of carbon dioxide production rate of TPU by 50.1%, 52.1% and 55.4%, respectively. Furthermore, the cotton/TPU hierarchical composites possessed the EMI shielding effectiveness of 40.0 dB in the X band and 54.6 dB in the K band. The mechanical property of the cotton/TPU hierarchical composites was also reinforced, where the elongation at break and toughness values of the TPU/SCF/mLDH1/C2 hierarchical composite were 21.47 and 18.30 times higher than those of pure TPU, respectively. These mechanically strong hierarchical composites have brought a promising attempt to broaden their practical application, removing the fire hazards and electromagnetic waves radiation from the environment.
