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1.
Int J Biol Macromol ; 272(Pt 1): 132639, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38834116

RESUMEN

Layer-by-layer (LBL) self-assembly is an effective strategy for constructing fire-resistant coatings on flexible polyurethane foam (FPUF), while the efficiency of fire-resistant coatings remains limited. Therefore, this study proposes an in situ flame retardancy modification combined with LBL self-assembly technology to enhance the efficiency of flame retardant coatings for FPUF. Initially, polydopamine (PDA) and polyethyleneimine (PEI) were employed to modify the FPUF skeleton, thereby augmenting the adhesion on the surface of the skeleton network. Then, the self-assembly of MXene and phosphorylated cellulose nanofibers (PCNFs) via the LBL technique on the foam skeleton network formed a novel, sustainable, and efficient flame retardant system. The final fire-protective coatings comprising PDA/PEI and MXenes/PCNF effectively prevented the collapse of the foam structure and suppressed the melt dripping of the FPUF during combustion. The peak heat release rate, the peak CO production rate and peak CO2 production rate were reduced by 68.6 %, 61.1 %, and 68.4 % only by applying a 10-bilayer coating. In addition, the smoke release rate and total smoke production were reduced by 83.3 % and 57.7 %, respectively. This work offers a surface modification approach for constructing highly efficient flame retardant coatings for flammable polymeric materials.


Asunto(s)
Celulosa , Retardadores de Llama , Indoles , Polímeros , Poliuretanos , Poliuretanos/química , Indoles/química , Celulosa/química , Polímeros/química , Fosforilación , Nanofibras/química , Incendios/prevención & control
2.
ACS Appl Mater Interfaces ; 11(32): 28900-28908, 2019 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-31318206

RESUMEN

Nanomaterials with tunnel structures are extremely attractive to be used for electrode materials in electrochemical energy storage devices. Tunnel-structured Ti-doped Na4Mn9O18 nanoparticles (TNMO-NPs) were synthesized by a facile and high-production method of the solid-state reaction with a high-energy ball-milling process. As electrode materials in the supercapacitor cell, the as-synthesized TNMO-NPs exhibit a high specific capacity of 284.93 mA h g-1 (0.57 mA h cm-2/1025.75 F g-1). A superior rate capability with a decay of 36% is achieved by increasing the scan rates from 2 to 25 mV s-1. To further explore the storage mechanism of Ti-doped Na4Mn9O18 materials, density functional theory (DFT) calculations were used to calculate the activation energy for the ion immigration in the electrode, and the results show that the minimum ion diffusion barrier energy is 0.272 eV, indicating that the sodium ions could insert into the system easily. Through the scan-rate-dependent cyclic voltammetry analysis, the capacity value indicates a mixed charge storage of capacitive behavior and Na+ intercalation progress. A maximum energy density of 77.81 W h kg-1 at a power density of 125 W kg-1 is achieved, and a high energy density of 54.79 W h kg-1 is maintained even at an ultrahigh power density of 3750 W kg-1. The TNMO-NP supercapacitors show excellent flexibility at various bent (0-180°) states. The capacitive performance of the TNMO-NPs makes them promising cathode materials for flexible supercapacitors with high specific capacities and high energy densities.

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