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131.
132.
Xuemei Wang Haixia Kou Juan Wang Tongtong Du Ruiju Teng Xinzhen Du Xiaoquan Lu 《Journal of separation science》2019,42(17):2851-2857
We herein presented a mesoporous cellular foam solid‐phase microextraction coating that showed highly sensitive recognition for weakly polarity polychlorinated biphenyls in water samples. The mesoporous cellular foam coater fiber was for the first time prepared by a simple sol‐gel method. The main experimental parameters including extraction temperature, extraction time, desorption time, stirring rate, and ionic strength were investigated by high‐efficiency orthogonal array design, a L16 (44) matrix was applied for the identification of optimized extraction parameters, and the optimized method was successfully applied to the analysis of environmental water sample. The novel mesoporous cellular foam coated fibers exhibited sensitive limits of detection (0.07–0.28 µg/L), wide linearity (5–3000 µg/L), and good reproducibility (3.5–8.3% for single fiber, and 4.9–8.7% for fiber‐to‐fiber) for polychlorinated biphenyls. The home‐made coating was successfully used in the analysis of polychlorinated biphenyls in real environmental water samples. These results indicate that the synthesized mesoporous cellular foams are promising materials for adsorption and separation applications in sample pretreatment. 相似文献
133.
Ming Xian Liu Li Hua Gan Ci Tian Jian Chun Zhu Zi Jie Xu Zhi Xian Hao Long Wu Chen 《中国化学快报》2009,20(1):123-126
We demonstrated a simple and effective dual-templating approach for the synthesis of hierarchically mesocellular carbon foams by using nonionic surfactant of sorbitan monooleate and silica colloid particles as sacrificial templates, and resorcinol/ formaldehyde as carbon source. The representative carbon foam has dual mesopore sizes of 4 and 10 nm, and possesses the specific surface area of 580 m2/g and the total pore volume of 0.80 cm3/g. 相似文献
134.
The axisymmetric and plane extrusion flows of a liquid foam are simulated assuming that the foam is a homogeneous compressible
Newtonian fluid that slips along the walls. Compressibility effects are investigated using both a linear and an exponential
equation of state. The numerical results confirm previous reports that the swelling of the extrudate decreases initially as
the compressibility of the fluid is increased and then increases considerably. The latter increase is sharper in the case
of the exponential equation of state. In the case of non-zero inertia, high compressibility was found to lead to a contraction
of the extrudate after the initial expansion, similar to that observed experimentally with liquid foams and to decaying oscillations
of the extrudate surface. The time-dependent calculations show that the oscillatory steady-state solutions are stable. These
steady-state oscillatory solutions are not affected by the length of the extrudate region nor by the boundary condition along
the wall. 相似文献
135.
The effect of polylactic acid (PLA), cellulose microfibers (CEL), and calcium carbonate (CaCO3) on the equilibrium moisture content (EMC), density and flexural mechanical properties of starch-based bio-foams was studied using a full factorial design 23. Also, a moisture aging study was carried out. The results show the three factors studied changed the bio-foams morphology, contribute to density increment, enhance dimensional stability and improve both the moisture resistance and the mechanical flexural properties. The moisture aging studies show that, although the flexural mechanical properties decrease with increasing humidity, the bio-foams exceed the mechanical properties of commercial expanded polystyrene (EPS) trays. These findings suggest the bio-composites could be used in regions where the humidity conditions are moderate to very humid, guaranteeing their dimensional stability and functional properties. Thus, these new bio-foams are an attractive and sustainable option to replace the non-biodegradable EPS commercial trays. 相似文献
136.
137.
Polymer‐Derived Silicoboron Carbonitride Foams for CO2 Capture: From Design to Application as Scaffolds for the in Situ Growth of Metal–Organic Frameworks 下载免费PDF全文
Dr. Fabien Sandra Dr. Martin Depardieu Dr. Zineb Mouline Prof. Gérard L. Vignoles Prof. Yuji Iwamoto Prof. Philippe Miele Prof. Rénal Backov Dr. Samuel Bernard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(24):8346-8357
A template‐assisted polymer‐derived ceramic route is investigated for preparing a series of silicoboron carbonitride (Si/B/C/N) foams with a hierarchical pore size distribution and tailorable interconnected porosity. A boron‐modified polycarbosilazane was selected to impregnate monolithic silica and carbonaceous templates and form after pyrolysis and template removal Si/B/C/N foams. By changing the hard template nature and controlling the quantity of polymer to be impregnated, controlled micropore/macropore distributions with mesoscopic cell windows are generated. Specific surface areas from 29 to 239 m2 g?1 and porosities from 51 to 77 % are achieved. These foams combine a low density with a thermal insulation and a relatively good thermostructural stability. Their particular structure allowed the in situ growth of metal–organic frameworks (MOFs) directly within the open‐cell structure. MOFs offered a microporosity feature to the resulting Si/B/C/N@MOF composite foams that allowed increasing the specific surface area to provide CO2 uptake of 2.2 %. 相似文献
138.
Gianluca A. Mannella Francesco Carfì Pavia Gioacchino Conoscenti Vincenzo La Carrubba Valerio Brucato 《Journal of Polymer Science.Polymer Physics》2014,52(14):979-983
Thermally induced phase separation is a fabrication technique for porous polymeric structures. By means of easy‐to‐tune processing parameters, such as system composition and demixing temperature, a vast latitude of average pore dimensions, pore size distributions, and morphologies can be obtained. The relation between demixing temperature and morphology was demonstrated via cloud point curve measurement and foams fabrication with controlled thermal protocols, for the model system poly‐l ‐lactide–dioxane–water. The morphologies obtained at a temperature lower than cloud point showed a closed‐pore architecture, suggesting a “nucleation‐and‐growth” separation mechanism, which produced larger pores at higher holding times. Conversely, the porous structures attained when holding the sample above the cloud point exhibited open pores with dimensions independent of time, denoting a phase separation occurring during sample freezing. Finally, the influence of the cooling rate on final morphology was investigated, showing a clear correlation with microstructure and pore size. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 979–983 相似文献
139.
The deformation properties of monotropic plastic foams under uniaxial compression or tension perpendicularly to the foam rise direction are considered. Theoretical results are obtained for the case where the volume- deformation hypothesis is assumed. In order to perform numerical calculations, the foams are devided into three groups with different degrees of monotropy. For these groups, different methods of calculating the numerical value of the relative volume strain are used. The Young's modulus in the plane of isotropy is determined using both the mixed Reuss-Voigt and Voigt averaging. The Poisson ratios are expressed using the Reuss averaging. If only the axial deformation of the load-bearing elements (polymer struts) is allowed for, the results obtained do not agree with experimental data. Therefore, we also take into account the changes in their orientation. The values of Young's modulus and Poisson ratios are obtained for a wide range of degrees of extension of the model cell. A comparison of the theoretical results with the experimental data available shows a satisfactory agreement. 相似文献
140.
Seven dependent elastic constants of monotropic plastic foams with an expressed strut-like structure are calculated. For this purpose, the basic results of the previously elaborated mathematical model for light-weight plastic foams is used. The model includes a model cell of local structure for monotropic/isotropic plastic foams and an ensemble of structural elements, which allows one to calculate the seven dependent elastic constants, taking into account the pronounced polydispersity of the structure of plastic foams. The numerical values of the constants are compared with the available experimental data, and a satisfactory agreement is found to exist. As a final result, a full set of general expressions and numerical values are obtained for all 12 elastic constants of monotropic plastic foams. 相似文献