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41.
Jinhong Kim Junho Jang Sehui Yun Hyeon Deok Kim You Young Byun Yong Tae Park Jung Il Song Chungyeon Cho 《大分子材料与工程》2021,306(9):2100233
In an effort to develop highly functionalized flame retardant materials, hybrid nanocoatings are prepared by alternately depositing a positively charged polyaniline (PANi) and negatively charged montmorillonite (MMT) using the layer-by-layer (LbL) assembly technique. Carbon nanotubes (CNTs) are employed in polymer nanocomposites as effective reinforcement, where nanotubes are stabilized in MMT aqueous solution. The 3D structure and high density of CNTs deposited in the PANi/CNTs-MMT multilayers produce thicker and heavier coatings in comparison to the LbL assemblies without CNTs. Vertical and horizontal flame testing show that the incorporation of CNTs improves fire resistance. Additionally, cone calorimetry reveals that stacking two nanomaterials (MMT and CNTs) in a single coating shows a significant reduction in peak heat release rate (up to 51%), total smoke release (up to 47%), and total heat release (up to 37%) for the polyurethane foam. The enhancement of flame retardancy is attributed to a synergistic effect; MMT serves as a physical barrier that retards the diffusion of heat and gas. The addition of CNTs strengthens the thermal stability and high char yield. These results, coupled with the simplicity with which the LbL deposition is applied, present a viable alternative to halogen-free flame retardant nanocoatings to natural and synthetic fibers. 相似文献
42.
The design and application of bioderived flame retardants have been widely conducted to meet the concept of green and sustainable development. Here, self-assembly technique is used to prepare core–shell bioderived additives by using β-FeOOH as the core and polydopamine (PDA)/tannic acid (TA) bilayer as the shell, following adsorption of nickel ions to enhance the thermal stability, flame retardancy, and mechanical properties of epoxy resin (EP). The molecular structure of biobased resources is rich in hydroxyl groups and carbon content, which can be dehydrated and carbonized during combustion and promote the formation of robust protective char layer. With the addition of 5 wt% β-FeOOH@PTNi, the EP composites can pass V-0 rating in the UL-94 test. The peak heat release rate and total heat release decrease by 28.4% and 17.4% compared with pure EP. The bioderived nanorods can capture the oxygen free radicals, contributing to flame retarding in gaseous phase. Thus, the release of high-toxic CO and flammable gaseous is significantly suppressed. Besides, the storage modulus of EP composites increases by 16.0% with the addition of 5% β-FeOOH@PTNi compared with pure EP. This work provides a sustainable methodology for the design of bioderived flame retardants for EP. 相似文献
43.
There is a growing demand to develop epoxy resins (EP) with smoke suppression as well as satisfactory flame retardancy. Herein, bio-based cobalt alginate is successfully fabricated and incorporated into EP to prepare EP/Cobalt Alginate composites with better fire safety performance. The addition of cobalt alginate reduces the thermal-decomposition rate, temperature at maximum weight-loss rate of EP, whereas obviously improves the thermal stabilities at a higher temperature range. Furthermore, the addition of cobalt alginate substantially reduces the fire hazard of EP, resulting in 56.2% reduction in peak heat release rate, as well as 17.8% and 56.3% reduction in total smoke production and peak smoke production rate, respectively, compared with EP matrix. Moreover, the presence of cobalt alginate increases smoke-suppressant properties, according to the smoke density test. Additionally, the incorporation of cobalt alginate has no obviously destructive effect on the mechanical properties of EP, while EP/Cobalt Alginate-3 exhibits a 27.0% improvement in impact strength. In prospective, this study may provide a significant method for producing eco-friendly flame retardant EP. 相似文献
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45.
磷氮阻燃腈纶结构性能及阻燃机理研究 总被引:5,自引:0,他引:5
研究了含磷酸二氢铵和脲复合阻燃剂的共混阻燃腈纶的结构和性能。研究表明,在纤维成形加工过程中,部分阻燃剂聚合生成聚磷酸铵和聚脲,阻燃剂以微粒状均匀分散并包埋在纤维内部;阻燃剂的加入使纤维高序区大分子间等距离排列的规整性和片状结构单元等距离平行排列的程度降低,热稳定性亦略有下降;但纤维的宏形态结构及物理机械性能没有明显变化;磷氮阻燃腈纶具有良好的阻燃性和阻燃耐久性,经碱洗20次、水洗30次后,阻燃剂的磷和氮的保留率分别高达82.9%和89.5%,纤维的LOI值仍在26%以上。 相似文献
46.
The extinction mechanism of a CH4/N2-air counterflow nonpremixed flame interacting with a single vortex was numerically studied. An augmented reduced mechanism was used to treat the CH4 oxidation reactions. The contribution of each term in the energy and the OH species equations were evaluated to investigate the unsteady extinction mechanism of nonpremixed flame. The flame temperature began to decrease due to the convection heat loss when the flame interacted with a vortex. The investigation of the radical behavior during the flame-vortex interaction process also provided useful information on the unsteady extinction mechanism. The OH radical concentration could be used as a good tracer of the state of the unsteady extinction of nonpremixed flame. The reduction mechanism of OH concentration was confirmed by analyzing the contribution of each term in the OH species equation. At initial stage of flame-vortex interaction, the OH production and consumption rates increased gradually, while the OH concentration was kept nearly constant. Near the extinction limit, the OH production rate decreased rapidly due to the low flame temperature, and the balance between the OH production and OH consumption by diffusion could not be maintained. The unsteady nonpremixed flame interacting with a vortex under the conditions of regime (V) shown in the spectral combustion diagram [Thévenin, D., Renard, P.H., Fiechtner, G.J., Gord, J.R., Rolon, J.C., 2000. Regimes of non-premixed flame-vortex interactions. Proceedings of the Combustion Institute 28, 2101-2108.] was finally extinguished due to low reactivity, which was induced by the low flame temperature. 相似文献
47.
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49.
火焰原子吸收光谱法测定苋菜中8种矿物元素 总被引:5,自引:0,他引:5
用空气-乙炔火焰原子吸收光谱法对苋菜中钾、钙、镁、铁、锌、铜、锰、铅8种矿物元素进行了测定,对样品前处理方法、酸度、共存元素干扰及元素线性范围进行了实验。在选定的实验条件下,可以用火焰原子吸收光谱法对苋菜中8种元素进行分别测定,互不干扰。方法的相对标准偏差为0.08%~3.17%(n=5),加标回收率为91.5%~102%。 相似文献
50.
Tri(acryloyloxyethyl) phosphate (TAEP) was blended in different ratios with epoxy acrylate EB600 and polyurethane acrylate EB270 to obtain a series of UV curable flame retardant resins. The thermal degradation mechanisms of their cured films in air were studied by thermogravimetric analysis, in situ Fourier‐transform infrared spectroscopy, and direct pyrolysis/mass spectrometry measurements. The results showed that the phosphate group in TAEP first degraded to form poly(phosphoric acid) before the degradation of EB600. Then, the formed poly(phosphoric acid) effectively promoted the conversion of EB600 to form char, which prevented the sample from further burning. However, urethane group in EB270 degraded simultaneously with phosphate group in TAEP, leading to not effectively increase the conversion of EB270 to char during the thermal degradation. It was thus found that the addition of TAEP more effectively improved the thermal stability, flame retardance, and the char yield during combustion of EB600 than those of EB270. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3130–3137, 2006 相似文献