The development of high-performance thermoplastic polyurethane (TPU) with high flame retardancy and low toxicity has always been the focus of its research. In this paper, the novel 3D hollow layered double hydroxide/molybdenum disulfide (LDH/MoS2) hybrid materials were synthesized by hydrothermal method using the MIL-88A as in situ sacrificial template and MoS2 as synergistic flame retardant. Among all TPU composites, the peak heat release rate, total heat release rate, and total smoke release rate of TPU/NiFeTb-LDH/MoS2 were reduced by 50.9%, 18.2%, and 35.8% compared with pure TPU, respectively. The results of the thermogravimetric infrared analysis demonstrated that the contents of combustible volatiles (hydrocarbons) and toxic volatiles (CO and HCN) emitted from TPU/LDH/MoS2 were significantly reduced, indicating that LDH/MoS2 hybrid materials can dramatically enhance the fire safety of TPU composites. Combined with the analysis of carbon residues and thermal stability of TPU composites, the enhanced flame retardancy and smoke suppression performances are primarily attributed to the catalytic carbonization of LDH and the physical barrier effect of MoS2.
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 by the melt blending method. Compared to pure TPU, NiCo-LDH/MoS2 filled TPU composite was endowed with a decrease of 30.9% and 55.7% of the peak heat release rate (PHRR) and the peak smoke production rate (PSPR), respectively. Furthermore, the addition of NiCo-LDH/MoS2 can significantly improve the thermal stability and char yield of the TPU composite. The catalytic carbonization effect and dilution effect of NiCo-LDH, and the barrier effect of MoS2 nanosheets enable TPU composites with excellent flame retardancy and toxic gas suppression ability.
Due to the widespread use of antibiotics in medical treatment, animal husbandry and aquaculture, a large number of antibiotics are discharged into the environment as metabolites or in their original state, causing pollution to water bodies, which is a serious issue. In this study, a novel nanocomposite adsorbent MIL-53/D201 was successfully prepared by hydrothermal synthesis. This approach overcomes the disadvantage of easy dissociation of MOF material in the water phase and realizes the efficient removal of antibiotic azlocillin sodium in water. The crystal morphology and basic structure of the composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy scattering spectroscopy (EDS), and specific surface area and porosity analyzer (BET). The results showed that MIL-53 was successfully synthesized in situ in D201. The results of adsorption experiments show that the maximum saturated adsorption capacity of the composite is 122.3 mg/g when the dosage of the composite is 1.0 g/L. Compared with pure MIL-53 material, the composite material exhibits greater stability and efficient adsorption performance for target pollutants at different pH values. The adsorption process accords with the quasi-second-order kinetic adsorption model and Langmuir adsorption isothermal model. After five cycles of adsorption and desorption, the removal rate of MIL-53/D201 to azlocillin sodium was still above 87%.
With the large-scale integration of renewable energy sources into the power system, a new source of uncertainty is added to the operation planning problem. In this paper, the rank correlation coefficient is introduced to characterize the dependency among random variables in power flow equations, and Nataf transformation is used to map the probabilistic power flow (PPF) problem to the independent standard normal space. Dimension reduction model is introduced to approximation the function relationship between PPF inputs and outputs. Gauss-Hermite quadrature is used to obtain the statistical moments of the univariate function, whereby the statistical moments of outputs of power flow equations are obtained. Testing on an IEEE-118 system, the dimension reduction method is compared with Hong’s point estimate method, it is found the dimension reduction method can improve the accuracy without extra computational burden.
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