Artykuły w czasopismach na temat „Foam”
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ABDULKADIR, H. K., E. J. EKEFAN i V. I. Gwa. "ANTAGONISTIC POTENTIAL OF Trichoderma harzianum AGAINST F. oxysporum f. sp. lycopersici ISOLATES CAUSING FUSARIUM WILT DISEASE OF TOMATO (Solanum lycopersicum L.)". FUDMA Journal of Agriculture and Agricultural Technology 9, nr 1 (17.05.2023): 143–49. http://dx.doi.org/10.33003/jaat.2023.0901.19.
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Antagonistic effect of T. harzianum was carried out on F. oxysporum f. sp. lycopersici. isolates of tomato variety (UC 82B) in a screen house located at the Teaching and Research Farm of Federal University of Agriculture, Makurdi during 2015 cropping season to determine the ability of the antagonistic in controlling Fusarium wilt diseases of tomato. The F. oxysporum isolates tested were coded as: FoAs1, FoAs2, FoAg, FoNb, FoSb, FoAm, FoAk, FoOr, FoAd and FoUAM together with an uninoculated control. The experiment was a 2 x 11 factorial laid out in Completely Randomized Design (CRD) and replicated three times. T. harzianum was introduced at three different times (Two days before, same time and two days after the inoculation of F. oxysporum). In vitro tests results revealed antagonistic effects of T. harzianum on F. oxysporum isolates. Growth inhibition was significantly higher (P≤0.05) when T. harzianum was introduced two days before inoculation of F. oxysporum. Interaction shows that T. harzianum introduced two days before inoculation of F. oxysporum gave better inhibition of all the Fusarium isolates tested except isolates FoAd and FoAg compared with when the antagonist was introduced at the same time and when it was introduced two days after inoculation of F. oxysporum. Also, T. harzianum (P≤0.05) totally inhibited the growth of isolates FoAg, FoAs1, FoNb, FoOr and FoUAM but not those of FoAd, FoAk, FoAm, FoAs2 and FoSb. It is therefore recommended that T. harzianum be used in the management of fusarium wilt disease of tomato
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Busahmin, Bashir, Brij Maini, Rama Rao Karri i Maziyar Sabet. "Studies on the Stability of the Foamy Oil in Developing Heavy Oil Reservoirs". Defect and Diffusion Forum 371 (luty 2017): 111–16. http://dx.doi.org/10.4028/www.scientific.net/ddf.371.111.
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In the process of natural energy depletion, foamy oil is characterized of low production Gas Oil Ratio, high oil viscosity, high daily production rate and high primary recovery factor. The stability of the foam turns out to be the prevailing factor that governs the life of the ‘foamy oil’. To enumerate the main factors affecting the stability of the foam, a high-temperature–high-pressure visualized experiment model for foamy oil stability test was developed. A serial of experiments was conducted to evaluate the performance of the foam stability. The effects of oil viscosity, height of the oil column, dissolved gas content and dispersed gas were investigated and recorded. These experiments were conducted using a Hele-Shaw, a high pressure cell. The volume of foamy oil produced, either by a step reduction in pressure or by a gradual (linear) reduction in pressure, and its subsequent decay was observed, visually. The experimental results show that foamy oil stability increases with higher oil viscosity, higher oil column, higher dissolved gas content and higher pressure decline rate. Asphaltene content was not observed to increase the foamy oil stability significantly. The results also show that the foam quality of foamy oils is much lower than aqueous foams.
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M. Al-Qararah, Ahmad. "Exploring Foam Drainage in Fiber-Foam: A Review". Applied Physics Research 15, nr 2 (14.09.2023): 98. http://dx.doi.org/10.5539/apr.v15n2p98.
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The foam drainage is extremely important in many situations where fiber foams are used. Enhancing wet foam stability requires a complete understanding of the mechanisms and factors affecting wet foam drainage. Investigation of the drainage behavior of fiber foams has been studied in this review. The mechanics behind fiber foam drainage are discussed in detail, along with the influence of surfactant concentration, fiber consistency, and other variables. It also investigated adding additives, such as chemi-thermo-mechanical pulp (CTMP), affects foam drainage. Highlighting the most recent developments in experimental and theoretical methods for describing and forecasting foam drainage behavior are presented. This review acts as a reference to offer useful understanding of the essential factors of foam drainage in fiber foams solution.
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Lo, King Him, Akira Miyase i Su S. Wang. "Stiffness predictions for closed-cell PVC foams". Journal of Composite Materials 51, nr 23 (6.12.2016): 3327–36. http://dx.doi.org/10.1177/0021998316683025.
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Light-weight polymeric foams are frequently used in composite sandwich construction in which foam core material properties could significantly influence the overall performance of the sandwich structure. Foam mechanical properties usually depend on a number of factors, including foam density, cell microstructure, and properties of foam–matrix polymer. Although the properties of foam–matrix polymer are determined mainly by the properties of the foam base (parent) polymer, they are also affected by other factors such as foam processing conditions. With the large number of material and microstructure parameters that influence foam properties, modeling mechanical behavior of polymeric foams could be quite involved, especially if foam behavior is anisotropic. This paper describes an effort to predict static elastic stiffness of closed-cell PVC foams. PVC foams are modeled as transversely isotropic materials with properties in the foam rise direction different from those in the planar (plane of isotropy) directions. An engineering approach, based on fibrous composites, is developed to predict in-plane and out-of-plane stiffness of PVC foams. The validity of the engineering model for the PVC foam stiffness is first demonstrated through comparison with test results on DIAB H80 foam obtained from a systematic in-house test program. Comparison of the predictions with the stiffness properties reported by a PVC foam manufacturer for various other density foams is also carried out. Good agreements are obtained for the cases studied. Comparison of stiffness predictions obtained in the paper with predictions from other published models of isotropic foam behavior is presented.
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Obisesan, Oyindamola, Ramadan Ahmed i Mahmood Amani. "The Effect of Salt on Stability of Aqueous Foams". Energies 14, nr 2 (6.01.2021): 279. http://dx.doi.org/10.3390/en14020279.
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The properties of foams are often affected by environmental variables such as salt contamination. The objective of this study is to investigate the impact of salt on the drainage behavior of aqueous foams. To accomplish this objective, drainage experiments were conducted on aqueous foams. Test variables were foam quality (40–65%), and salt content (0% to 18%), and type. To investigate drainage, the foam was generated in a flow loop and trapped in a vertical test section. Then, the pressure profile in the foam column was measured using ten pressure sensors. Foam drainage is determined as a function of time using measured pressure profiles. The results show that the drainage of NaCl-containing foams decreased with foam quality, whereas the CaCl2-containing foams did not exhibit a clear trend with foam quality. The effect of salt content on foam rheology was minimal.
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Zhou, Xia, Zhihao An, Ziheng Liu, Hongjie Ha, Yixuan Li i Renming Pan. "The Influence of the Heat Transfer Mode on the Stability of Foam Extinguishing Agents". Fire 7, nr 4 (12.04.2024): 137. http://dx.doi.org/10.3390/fire7040137.
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The mass loss mechanisms of an aqueous film-forming foam (AF foam), an AR/AFFF water-soluble film-forming foam extinguishing agent (AR foam), and a Class A foam extinguishing agent (A foam) at different levels of thermal radiation, thermal convection, and heat conduction intensity were studied. At a relatively low thermal radiation intensity, the liquid separation rate of the AF, AR, and A foams is related to the properties of the foam itself, such as viscosity and surface/interface tension, which are relatively independent of the external radiation heat flux of the foam. At low radiation intensity (15 kW/m2 and 25 kW/m2), the liquid separation rate of the AF and A foams is relatively stable. When the heat flux intensity is 35 kW/m2, the liquid separation rate of the AF and A foams increases notably, which may be mainly due to the rapid decrease in foam viscosity. And the mass loss behavior is dominated by liquid separation in the AF, AR, and A foams under the influence of thermal radiation and thermal convection. Under the same experimental conditions, the liquid separation rate of AF is the fastest. There is no significant difference in the evaporation rates of the three kinds of foam in the same heat conduction condition. In addition, the AR and A foams usually have a 25% longer liquid separation time (t) under thermal radiation and thermal convection, and the thermal stability is better than AF foam. The temperature reached by the AF foam layer under thermal convection was lower than that of the AR and A foams, and the time for the foam layer to reach the highest temperature under heat conduction was longer than that of the AR and A foams.
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HONKANEN, MARKUS, i HANNU ELORANTA. "Advanced real-time digital microscopy of foaming processes". January 2023 22, nr 1 (24.01.2023): 21–31. http://dx.doi.org/10.32964/tj22.1.21.
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The properties of aqueous foams play a major role in foam forming and foam coating. Inline real-time foam measurements provide highly desired opportunities for optimization and control of foaming processes. This paper presents inline digital microscopy measurements of aqueous foams in foaming processes. It presents methods for providing detailed information on foam quality parameters, such as foam density and foam homogeneity in real time from the process. In addition, this study evaluates the performance of transillumination and front-light illumination in imaging of foams. The tests show very good results for the transillumination approach. Limitations of the image-based optical technique are discussed, and the precision of bubble size distribution measurement is assessed with a certificated reference substance. The measured foam densities are compared against the reference foam densities in the range 100–300 g/L, providing a linear correlation with R2 value of 0.99. In the case of heterogenous foams with a wide bubble size distribution, the bubble size-dependent dimensionless depth of field must be taken into account to obtain accurate estimates of foam density. Bubble-scale foam homogeneity is described by the standard deviation of bubble size distribution in foam.
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Babcsán, N., F. Garcia-Moreno, D. Leitlmeier i John Banhart. "Liquid-Metal Foams – Feasible In Situ Experiments under Low Gravity". Materials Science Forum 508 (marzec 2006): 275–80. http://dx.doi.org/10.4028/www.scientific.net/msf.508.275.
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Metal foams are quite a challenge to materials scientists due to their difficult manufacturing. In all processes the foam develops in the liquid or semiliquid state. Liquid-metal foams are complex fluids which contain liquid metals, solid particles and gas bubbles at the same time. An X-ray transparent furnace was developed to monitor liquid metal foam evolution. Aluminium foams - similar to the commercial Metcomb foams - were produced by feeding argon or air gas bubbles into an aluminium composite melt. The foam evolution was observed in-situ by X-ray radioscopy under normal gravity. Drainage and rupture were evaluated during the 5 min foam decay and 2 min solidification. Argon blown foams showed significant drainage and cell wall rupture during the first 20 s of foam decay. Air blown foams were stable and neither drainage nor rupture occurred. We demonstrated the feasibility of experiments during parabolic flight or drop tower campaigns. However, the development of a foam generator for low gravity is needed.
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Lee, W., S. Lee, M. Izadi i S. I. Kam. "Dimensionality-Dependent Foam Rheological Properties: How To Go From Linear to Radial Geometry for Foam Modeling and Simulation". SPE Journal 21, nr 05 (22.04.2016): 1669–87. http://dx.doi.org/10.2118/175015-pa.
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Summary Numerous laboratory and field tests reveal that foam can effectively control gas mobility and improve sweep efficiency, if correctly designed. It is believed that there is a significant gap between small laboratory-scale experiments and large field-scale tests because of two main reasons: (1) Typical laboratory flow tests are conducted in linear systems, whereas field-scale foam enhanced-oil-recovery (EOR) processes are performed in radial (or spherical partly) systems and (2) through the complicated in-situ lamella creation/coalescence mechanisms and non-Newtonian behavior, foam rheology depends on the geometry and dimensionality. As a result, it is still an open question as to how to translate laboratory-measured data to field-scale treatments. Motivated by earlier studies of Kovscek et al. (1994, 1997), this study investigates how such dimensionality-dependent foam rheological properties are affected by different injection conditions on small and large scales, with a mechanistic foam-modeling technique. Complex foam-flow characteristics such as three foam states (weak-foam, strong-foam, and intermediate states) and two steady-state strong-foam regimes (high-quality regime and low-quality regime) lie in the heart of this analysis. The calculation results from small radial and spherical systems showed that (1) for strong foams in the low-quality regime injected, foam mobility decreased [or mobility reduction factor (MRF) increased] significantly with distance showing a good sweep efficiency; (2) for strong foams in the high-quality regime, the situation became more complicated—near the well, foam mobility decreased, but away from the well, foam mobility increased with distance, which eventually gave a relatively low sweep efficiency; and (3) for weak foams injected, foam mobility increased with distance showing a poor sweep efficiency. The results implied that the use of a fixed value of MRF, which is a common practice in field-scale reservoir simulations, might lead to a significant error. When the method was applied to a larger scale, it was shown that strong foams could propagate deeper into the reservoir at higher injection rate, higher injection pressure, and at lower injection foam quality. Foam-propagation distance was very sensitive to these injection conditions for strong foams in the high-quality regime, but much less sensitive for strong foams in the low-quality regime.
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Amir, N., Mohamed Syakir Mohamed Hisham i Kamal Ariff Zainal Abidin. "Study of Physical Properties and Shock Absorption Abilities of Starch Polymer Foam as Cushioning Material for Packaging". MATEC Web of Conferences 225 (2018): 06010. http://dx.doi.org/10.1051/matecconf/201822506010.
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Lack of information about the formulation and fabrication process of starch polymer foam and lack of study in the shock absorption ability of starch polymer foam were the reasons this research was executed. In this project starch polymer foam was produced to be used as cushioning material for packaging. Starch polymer foam were developed from starch, polyvinyl alcohol (PVA), urea, citric acid, and deionised water. Water amount with drying and curing process were the variables manipulated to produce the best starch polymer foam. It was determined then, that the optimized ratio of starch:PVA:citric acid was 1:1:4. The amount of water used was 10 ml/gram of starch/PVA weight. The suitable foaming mixing was done at a speed of 1500 rpm for 40 minutes. Drying process was done at 70°C for 24 hours, followed by curing process at 100°C for 1 hour to produce closed-cell foam. While for the open-cell foam, the foam was dried and cured at 100ºC for 6 hours. The open-cell and closed-cell foams produced were cut to 6 cm height x 6 cm width x 0.5 cm thick. The average density was calculated and then the foams were subjected to weight drop destructive test. The test was done by placing a foam on top of a piece of mirror, and a weight is dropped onto the foam, with increasing height until the mirror break. Three weights were used with mass of 50 g, 100 g and 200 g. The starch foams were compared to polyurethane and polystyrene foams in terms of the minimum height that can cause the mirror to break. The results showed that starch closed-cell foam absorbed the highest impact energy followed by polystyrene foam, starch open-cell foam and polyurethane foam.
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Hall, Robin, i Robin K. Mackenzie. "Reconstituted Versus Virgin Open Cell Foams in Floating Floors". Building Acoustics 2, nr 2 (czerwiec 1995): 419–36. http://dx.doi.org/10.1177/1351010x9500200202.
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Sound reducing flooring systems using flexible polymer foams as a decoupling resilient layer are increasingly being used in both new build and refurbishment. Such foams have been investigated and results suggest that reconstituted polyether foam from waste products may offer some advantages over the low density open cell l.d.o.c.) foams currently used in some systems. It has been shown that reconstituted open cell (o.c.) foams have an almost linear compressive stress-strain relationship up to about 40% strain without the marked yield point observed with virgin o.c. foams. Stress strain characteristics for reconstituted o.c. and virgin l.d.o.c. foams compared in this study indicate that, for stresses below the yield point for the virgin foam, greater strain is observed in reconstituted foam. When tested according to BSEN 29052-1, systems comprising reconstituted foam exhibited lower natural frequencies than those with the lower density virgin foam.
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Yu, Yang, Zhuokun Cao, Ganfeng Tu i Yongliang Mu. "Energy Absorption of Different Cell Structures for Closed-Cell Foam-Filled Tubes Subject to Uniaxial Compression". Metals 10, nr 12 (26.11.2020): 1579. http://dx.doi.org/10.3390/met10121579.
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The energy absorption of different cell structures for closed-cell aluminum foam-filled Al tubes are investigated through quasi-static compression testing. Aluminum foams are fabricated under different pressures, obtaining aluminum foams with different cell sizes. It is found that the deformation of the foam core is close to the overall deformation, and the deformation band is seriously expanded when the cell size is fined, which leads to the increase of interaction. Results confirm that the foam-filled tubes absorb more energy due to the increase of interaction between the foam core and tube wall when the foaming pressure increases. The energy absorption efficiency of foam-filled tubes can reach a maximum value of 90% when the foam core is fabricated under 0.30 MPa, which demonstrates that aluminum foams fabricated under increased pressure give a new way for the applications of foam-filled tubes in the automotive industry.
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Mines, Robert A. W. "Strain Rate Effects in Crushable Structural Foams". Applied Mechanics and Materials 7-8 (sierpień 2007): 231–36. http://dx.doi.org/10.4028/www.scientific.net/amm.7-8.231.
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Structural foams are used as cores in sandwich construction. In the application of foreign object impact loading of sandwich structures, the core will suffer dynamic multi axial deformation and crush. This means that experimental study is required for the crush behaviour of structural foams at various strain rates, and numerical simulation foam models need to be calibrated with dynamic data. A number of foams are considered, namely Divinycell PVC foam, Rohacell PMI foam and Alporas aluminium foam. Also, new generation metallic micro lattice structures are discussed
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Mosleh, Yasmine, Kelly Vanden Bosche, Bart Depreitere, Jos Vander Sloten, Ignaas Verpoest i Jan Ivens. "Effect of polymer foam anisotropy on energy absorption during combined shear-compression loading". Journal of Cellular Plastics 54, nr 3 (11.07.2017): 597–613. http://dx.doi.org/10.1177/0021955x17720156.
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Polymeric foams are extensively used in applications such as packaging, sports goods and sandwich structures. Since in-service loading conditions are often multi-axial, characterisation of foams under multi-axial loading is essential. In this article, quasi-static combined shear-compression behaviour of isotropic expanded polystyrene foam and anisotropic polyethersulfone foam was studied. For this, a testing apparatus which can apply combined compression and transverse shear loads was developed. The results revealed that the shear and compression energy absorption, yield stress and stiffness of foams are dependent on deformation angle. The total energy absorption of the anisotropic polyethersulfone foam is shown to be direction dependent in contrast to isotropic expanded polystyrene. Furthermore, for similar relative density, polyethersulfone foam absorbs more energy than expanded polystyrene foam, regardless of deformation angle. This study highlights the importance of correct positioning of foam cells in anisotropic foams with respect to loading direction to maximise energy absorption capability.
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Dong, Hua Qiao, Jun Liang, Fu Yang Li, Cheng Chuan Zhang, Song Bao Wang i Zuo Sheng Lei. "Structural Transformation of Bilayer Ferro-Foams Caused by Magnetic Field". Materials Science Forum 933 (październik 2018): 22–31. http://dx.doi.org/10.4028/www.scientific.net/msf.933.22.
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Previous researchers have proved that units constituting monodisperse bilayer foams can transform reversibly by changing foam liquid fraction. Structural transformation of bilayer ferro-foams caused by magnetic field is investigated in this paper. It is observed that bilayer ferro-foams transform from Tóth structure to honeycomb structure caused by liquid fraction change which attributes to foam imbibition under a uniform magnetic gradient field. In order to acquire critical structural transformation liquid fraction range, foam liquid fractions are calculated by image analysis. However, we also observed that, when applying a homogeneous magnetic field, bilayer ferro-foams can also perform this transformation at a constant liquid fraction. This phenomenon is related to energy absorption of foam system, which is induced by magnetic interaction of magnetic moments after applying a magnetic field. This self-organizational behavior of foam structure is believed to be based on energy minimization principle. This study opens possible applications in the field of metal foam preparation.
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Mosleh, Yasmine, Bart Depreitere, Jos Vander Sloten i Jan Ivens. "Decoupling shear and compression properties in composite polymer foams by introducing anisotropy at macro level". Journal of Reinforced Plastics and Composites 37, nr 10 (16.02.2018): 657–67. http://dx.doi.org/10.1177/0731684418758926.
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Anisotropy in foams generally originates from cell elongation in a certain direction. In this study, a composite concept is utilized to create anisotropy in foams at macro level. For this, layered composite foam is proposed by combining discrete layers of expanded polystyrene foam foam with different densities. The layers are positioned in parallel with the prime loading direction. The compression and biaxial combined shear-compression behavior of the composite foams are studied and compared with single-layer expanded polystyrene foam of equivalent density. The biaxial shear-compression test results demonstrate that the composite concept enables to decouple shear and compression properties of foam for a given overall density. In compression loading, the composite foam behavior is similar to that of single-layer foam of similar density, while in biaxial loading, the composite foam shows lower shear resistance than single-layer foam. Moreover, in biaxial loading, parameters such as the number of layers and the density difference between the high- and low-density layers affect the extent of decrease in shear resistance, while the compression stress component depends solely on the overall density of the composite foam. One of the potential applications of this behavior could be in protective helmets for mitigation of the head rotational acceleration.
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Sheng, Youjie, Canbin Yan, Yang Li, Yunchuan Peng, Li Ma i Qiuhong Wang. "Thermal Stability of Gel Foams Stabilized by Xanthan Gum, Silica Nanoparticles and Surfactants". Gels 7, nr 4 (22.10.2021): 179. http://dx.doi.org/10.3390/gels7040179.
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The foams stabilized by nanoparticles (NPs), water-soluble polymers, and surfactants have potential application prospects in the development of new, environmentally friendly firefighting foams. In the present study, a gel foam containing a water-soluble polymer (xanthan gum, XG), hydrophilic silica NPs, hydrocarbon surfactant (SDS), and fluorocarbon surfactant (FS-50) were prepared. The surface activity, conductivity, viscosity, and foaming ability of foam dispersions were characterized. The gel foam stability under a radiation heat source and temperature distribution in the vertical foam layer were evaluated systematically. The results show that the addition of NPs and XG has a significant effect on the foaming ability, viscosity and foam thermal stability, but has a very subtle effect on the conductivity and surface activity. The foaming ability of the FS-50/SDS solution was enhanced by the addition of NPs, but decreased with increasing the XG concentration. The thermal stability of the foams stabilized by SDS/FS-50/NPs/XG increased with the addition of NPs and increasing XG concentration. Foam drainage and coarsening were significantly decelerated by the addition of NPs and XG. The slower foam drainage and coarsening are the main reason for the intensified foam thermal stability. The results obtained from this study can provide guidance for developing new firefighting foams.
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Lohtander, Tia, Reima Herrala, Päivi Laaksonen, Sami Franssila i Monika Österberg. "Lightweight lignocellulosic foams for thermal insulation". Cellulose 29, nr 3 (6.01.2022): 1855–71. http://dx.doi.org/10.1007/s10570-021-04385-6.
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AbstractFoams are mainly composed of dispersed gas trapped in a liquid or solid phase making them lightweight and thermally insulating materials. Additionally, they are applicable for large surfaces, which makes them attractive for thermal insulation. State-of-the-art thermally insulating foams are made of synthetic polymeric materials such as polystyrene. This work focuses on generating foam from surfactants and renewable lignocellulosic materials for thermally insulating stealth material. The effect of two surfactants (sodium dodecyl sulphate (SDS) and polysorbate (T80)), two cellulosic materials (bleached pulp and nanocellulose), and lignin on the foaming and stability of foam was investigated using experimental design and response surface methodology. The volume-optimized foams determined using experimental design were further studied with optical microscopy and infrared imaging. The results of experimental design, bubble structure of foams, and observations of their thermal conductivity showed that bleached pulp foam made using SDS as surfactant produced the highest foam volume, best stability, and good thermal insulation. Lignin did not improve the foaming or thermal insulation properties of the foam, but it was found to improve the structural stability of foam and brought natural brown color to the foam. Both wet and dry lignocellulosic foams provided thermal insulation comparable to dry polystyrene foam. Graphical abstract
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Guo, Sy-Jye, i Hsiu-Fen Tsai. "Analysis on Thermal Hazard of Foam Decoration Materials". Advances in Materials Science and Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/168143.
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The occurrence and spread of fire often result from the flammables in interior decoration materials, which mostly contain fireproof foam to avoid fire damage. In this study, the foams with reportedly fire resistance, such as general foam, PU foam, melamine foam, and rubber foam, are compared via thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis to build a thermal parameter database of decoration materials of fireproof foams and provide green building materials, technologies, and fire preventive measures to the industry or consumers.
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Glenn, Gregory M., Gustavo H. D. Tonoli, Luiz E. Silva, Artur P. Klamczynski, Delilah Wood, Bor-Sen Chiou, Charles Lee, William Hart-Cooper, Zach McCaffrey i William Orts. "Effect of Starch and Paperboard Reinforcing Structures on Insulative Fiber Foam Composites". Polymers 16, nr 7 (26.03.2024): 911. http://dx.doi.org/10.3390/polym16070911.
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Single-use plastic foams are used extensively as interior packaging to insulate and protect items during shipment but have come under increasing scrutiny due to the volume sent to landfills and their negative impact on the environment. Insulative compression molded cellulose fiber foams could be a viable alternative, but they do not have the mechanical strength of plastic foams. To address this issue, a novel approach was used that combined the insulative properties of cellulose fiber foams, a binder (starch), and three different reinforcing paperboard elements (angular, cylindrical, and grid) to make low-density foam composites with excellent mechanical strength. Compression molded foams and composites had a consistent thickness and a smooth, flat finish. Respirometry tests showed the fiber foams mineralized in the range of 37 to 49% over a 46 d testing period. All of the samples had relatively low density (Dd) and thermal conductivity (TC). The Dd of samples ranged from 33.1 to 64.9 kg/m3, and TC ranged from 0.039 to 0.049 W/mk. The addition of starch to the fiber foam (FF+S) and composites not only increased Dd, drying time (Td), and TC by an average of 18%, 55%, and 5.5%, respectively, but also dramatically increased the mechanical strength. The FF+S foam and paperboard composites had 240% and 350% higher average flexural strength (σfM) and modulus (Ef), respectively, than the FF-S composites. The FF-S grid composite and all the FF+S foam and composite samples had equal or higher σfM than EPS foam. Additionally, FF+S foam and paperboard composites had 187% and 354% higher average compression strength (CS) and modulus (Ec), respectively, than the FF-S foam and composites. All the paperboard composites for both FF+S and FF-S samples had comparable or higher CS, but only the FF+S cylinder and grid samples had greater toughness (Ωc) than EPS foam. Fiber foams and foam composites are compatible with existing paper recycling streams and show promise as a biodegradable, insulative alternative to EPS foam internal packaging.
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Jang, Lindy K., Landon D. Nash, Grace K. Fletcher, Thomas Cheung, Andrew Soewito i Duncan J. Maitland. "Enhanced X-ray Visibility of Shape Memory Polymer Foam Using Iodine Motifs and Tantalum Microparticles". Journal of Composites Science 5, nr 1 (6.01.2021): 14. http://dx.doi.org/10.3390/jcs5010014.
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Shape memory polymer (SMP) foams are porous materials with high surface area and large volumetric expansion capabilities that are well suited for endovascular occlusion applications, including brain aneurysm embolization. However, many polyurethane SMP foams are inherently radiolucent when X-ray visibility is required to ensure the safe delivery of the foam to the targeted aneurysm site using fluoroscopy. Here, highly radio-dense tantalum microparticles were added to a previously reported triiodobenzene-containing SMP foam (ATIPA foam) premix to fabricate ATIPA foam-tantalum composites (AT_T). The AT_T foams showed comparable glass transition temperatures, faster expansion profiles, increased X-ray visibility, good cytocompatibility, and faster oxidative degradation compared to the control ATIPA foam without tantalum. The mechanical properties were improved up to 4 vol% tantalum and the X-ray visibility was most appropriate for the 2 vol% (AT_2%T) and 4 vol% (AT_4%T) tantalum foams. E-beam sterilization did not impair the critical properties of the ATIPA foams. Overall, AT_2%T was the optimal foam composition for neurovascular prototypes due to its high oxidative stability in vitro compared to previous low-density SMP foams. The AT_T foams are very promising materials with high toughness and sufficient X-ray visibility for use as neurovascular embolization devices.
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Lo, King H., Akira Miyase i Su Su Wang. "Failure strength predictions for closed-cell polyvinyl chloride foams". Journal of Composite Materials 52, nr 30 (17.05.2018): 4185–201. http://dx.doi.org/10.1177/0021998318777049.
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This paper describes an effort to model mechanical strength of closed-cell polyvinyl chloride foams under static loading. The study presented here is a continuation of an earlier study to model elastic stiffness of closed-cell polyvinyl chloride foams as effective transversely isotropic materials. An engineering approach is used in the study and governing equations are developed for predicting the strength of polyvinyl chloride foams. To account for foam microstructure and cell-shape anisotropy on foam strength, a unit cell representation of the polyvinyl chloride foam microstructure is used to derive equations to assess tensile and shear strengths of polyvinyl chloride foams. The differential stretching of polyvinyl chloride foam cell walls (in the rise direction and in the in-plane directions) on the strength of the foam-matrix polymer is also taken into account in modeling the mechanical strength of polyvinyl chloride closed-cell foams. The behavior of closed-cell polyvinyl chloride foams under compression is different from that under tension. In the paper, the equations for predicting compressive strength of closed-cell polyvinyl chloride foams are based on an approximate theory developed in an earlier study of compressive strength of unidirectional composites. The validity of the foam strength predictive equations, derived in the paper, is first demonstrated through comparison of the predictions with the results on Divinycell H (DIAB) foams obtained from a systematic in-house test program. A comparison is also carried out between the strength predictions and the test results published by two polyvinyl chloride foam manufacturers for different density polyvinyl chloride foams. Good agreements are found for all the different density foams studied.
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Manetti, L. L., A. S. Moita i E. M. Cardoso. "Thermal efficiency of metal foams on pool boiling". Journal of Physics: Conference Series 2116, nr 1 (1.11.2021): 012005. http://dx.doi.org/10.1088/1742-6596/2116/1/012005.
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Abstract This paper presents an experimental work on pool boiling using HFE-7100 at saturated conditions, under atmospheric pressure, and copper and nickel foams as the heating surface with four different thicknesses varying between 0.5 mm and 3 mm, followed by an analysis of the effect of foam fin-efficiency based on Ghosh model. All foams showed a better heat transfer coefficient (HTC) than the plain surface; however, as the heat flux increased, the HTC from the thicker nickel foams decreased due to the bubble vapor flow inside the foam. On the other hand, the thinner nickel foam showed better HTC at high heat fluxes with a maximum enhancement of 120%. The foam efficiency presented a similar tendency with the HTC, i.e., as the thickness decreases the efficiency increases; however, as compared with copper foams with a similar area but different porous diameter, the copper foams are 40% more efficient than the nickel ones due to the foam material, which has a thermal conductivity 4.5 times higher.
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Asavavisithchai, Seksak, Natthida Jareankieathbovorn i Areeya Srichaiyaperk. "Investigation of AC8A Scrap-Recycled Aluminum Foams". Advanced Materials Research 894 (luty 2014): 134–37. http://dx.doi.org/10.4028/www.scientific.net/amr.894.134.
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Open-cell Al foam has outstanding properties which are suitable for functional applications. However, a major drawback for widespread employment of Al foam is its high relative cost which can be several times higher than conventional metals. To reduce the cost, a recycled material waste is constructively used instead of expensive base metal. The present study aims to fabricate economical open-cell Al foams using AC8A alloy scrap from lathe machines. The Al foams were fabricated through pressure infiltration casting process at which the cellular pattern was made from commercial reticulated open-cell polyurethane foams with the pore size of 12 ppi. The compressive strength and microhardness of scrap-recycled Al foams are higher than those of pure Al foam. The increase in foam mechanical properties resulted from the change in foam microstructure as the formation of Si hard phase in Al matrix. The strength and microhardness of the foams increase with increasing scrap contents.
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Duncan, Olly, George Naylor, Joel Godfrey M, Tom Allen, Leon Foster, John Hart i Andrew Alderson. "Plantar Pressure Distribution under Uniform and Gradient Foam during Running and Jumping". Proceedings 49, nr 1 (15.06.2020): 116. http://dx.doi.org/10.3390/proceedings2020049116.
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Auxetic materials have a negative Poisson’s ratio, meaning they contract laterally during axial compression. Auxetics can also absorb more energy during impacts than conventional materials. Auxetic foam was fabricated by volumetrically compressing open cell foam to buckle cell ribs and impart a re-entrant cell structure, then the imposed structure was fixed by heating and cooling. Passing pins through the foam allowed localised control over compression during fabrication, producing gradient foam with regions with differing Poisson’s ratios and stress vs. strain relationships. Uniform sheets had volumetric compression ratios of three, gradient sheets had volumetric compression ratios of one (unchanged) or three in different regions. One participant jumped barefoot on all foams, cut out to fit pressure sensors; another ran wearing shoes containing uniform converted and unconverted foam insoles. Pressure distribution was measured underneath the foams and foam insoles. Peak pressure was lowest underneath converted foams, warranting further investigation with more participants.
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Fuller, A. J., T. Kim, H. P. Hodson i T. J. Lu. "Measurement and interpretation of the heat transfer coefficients of metal foams". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 219, nr 2 (1.02.2005): 183–91. http://dx.doi.org/10.1243/095440605x8414.
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The heat transfer characteristics of FeCrAlY (an iron-based alloy with a melting point of 1510°C sintered foams are presented. The foams have open cells and hollow cell ligaments. The foam samples had a range of cell sizes (1-3 mm) and relative densities (4.6-12.5 percent). Foam cores sandwiched between two conductive substrates were subjected to forced air convection with a constant input heat flux. The volumetric heat transfer coefficient is shown to depend on the effective porosity. Heat transfer is predominantly due to the increased flow mixing that the foam structure promotes. With higher-conductivity materials, the foam also acts to increase the heat transfer by providing an extended surface area, but this is not a strong effect in FeCrAlY foams owing to the low thermal conductivity of 16 W/m K. The FeCrAlY foam is compared with copper foam, and the latter effect is more significant.
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Majib, Nur Mawaddah, Sam Sung Ting, Noorulnajwa Diyana Yaacob, Nor Munirah Rohaizad i Lee Boon Beng. "Effects of different biomass on the properties of Pleurotus Djamor eco-friendly foam". E3S Web of Conferences 437 (2023): 03004. http://dx.doi.org/10.1051/e3sconf/202343703004.
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Plastic waste and polyurethane foam are major sources of pollution that threatens environments’ biodiversity. The objective of the study is to create an eco-friendly foam from Pleorotus djamor mycelium, rice husk and sugarcane bagasse. The mushroom industry’s overabundance of materials, like oyster mushrooms and biomass, has provided an alternative method to make foam that could be beneficial for the environment. The biomass, consisting of rice husk and sugarcane bagasse, both of which are necessary for the production of foam, was evaluated as a substrate. Pleurotus djamor was inoculated on both substrates and test was done on both produced foams. Mechanical tests showed that rice husk foam had higher hardness and less springy than sugarcane bagasse foam. The morphology of both foams was analyzed using a scanning electron microscope (SEM), and the results show that sugarcane bagasse foam is denser than rice husk foam.
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Sullivan, W. F., i A. K. Thomas. "The Use of An All CO2 Blown Foam in Production". Cellular Polymers 11, nr 1 (styczeń 1992): 18–28. http://dx.doi.org/10.1177/026248939201100102.
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Prior to the Montreal Protocol on ozone depleting substances, dichlorofluoromethane (CFC-11) had been widely used in polyurethane foam formulations as both a blowing agent and to endow the foam with excellent insulation properties. Now, U.S. manufacturers of products containing rigid polyurethane foam insulation must face the challenge of eliminating CFC-11 from their products. This must be done while retaining the excellent insulation properties that have made PUR foam the most effective insulation material in use today. Elimination of CFC-11 without any reduction in foam insulation efficiency can be achieved with novel foam systems now in commercial use. These foam systems use C02 as a replacement for CFC-11, but otherwise they are equivalent to CFC-11 based foams in all other respects. Insulated vending equipment is being produced with foam using all C02 blowing and the foam performance is equivalent to, and in some respects better than, the CFC-based foam it replaced. The vending machines have been tested for dimensional stability and energy consumption and initial measurements indicate that the new C02 blown foam gives the same results as CFC-based foams. Of particular concern to manufacturers is the processability of all C02 blown insulation foams. An experimental design was used to evaluate the processing latitude of variables such as chemical temperatures, mixing pressures, and fixture and preheat temperatures. The effect of varying these process variables on foam performance is reviewed. Particularly how these process variables affect demould time, adhesion, overall physical properties and insulation value.
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Ravi Kumar, N. V., Hina Gokhale i Amol A. Gokhale. "Role of SiCP on Processing and Physical Characteristics of Al-Si-Mg/SiCP Composite Foams". Materials Science Forum 710 (styczeń 2012): 383–88. http://dx.doi.org/10.4028/www.scientific.net/msf.710.383.
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Metallic foams find specialised applications in industry due to their unique properties such as ultra light weight and high impact energy absorption. When ceramic particles (e.g. SiC, Al2O3) are present, metal matrix composite (MMC) foams can be fabricated. Further it is known theoretically that foam strength is proportional to strength of foam material, and also it has been established that metal matrix composites exhibit better strength vis-à-vis their matrix metal. Accordingly, the present work is undertaken to study the processing of composite foams. Al-Si-Mg/SiCP foams were successfully prepared via liquid metallurgy processing using TiH2. The role of particle size, volume fraction (5 to 20 vol. %), and temperature (640 and 670°C) on foaming tendency were explored using the design of experiments approach. Liquid foams with reasonably good expansions could be achieved for all the combinations of particle size, volume %, and foaming temperature. Temperature has a dominant effect on foam collapse (decay) during solidification, irrespective of the particle size and vol. %. For foams processed at 640°C, the cell size variation is marginal along the foam height, except at the top portion which has finer cells. The evolution of foam, and the role of SiC on foam stability are discussed based on macro and microstructural results.
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Koblischka, Michael Rudolf, Anjela Koblischka-Veneva, Quentin Nouailhetas, Ghazi Hajiri, Kévin Berger, Bruno Douine i Denis Gokhfeld. "Microstructural Parameters for Modelling of Superconducting Foams". Materials 15, nr 6 (20.03.2022): 2303. http://dx.doi.org/10.3390/ma15062303.
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Superconducting YBa2Cu3Oy (YBCO) foams were prepared using commercial open-cell, polyurethane foams as starting material to form ceramic Y2BaCuO5 foams which are then converted into superconducting YBCO by using the infiltration growth process. For modelling the superconducting and mechanical properties of the foam samples, a Kelvin-type cell may be employed as a first approach as reported in the literature for pure polyurethane foams. The results of a first modelling attempt in this direction are presented concerning an estimation of the possible trapped fields (TFs) and are compared to experimental results at 77 K. This simple modelling revealed already useful information concerning the best suited foam structure to realize large TF values, but it also became obvious that for various other parameters like magnetostriction, mechanical strength, percolative current flow and the details of the TF distribution, a refined model of a superconducting foam sample incorporating the real sample structure must be considered. Thus, a proper description of the specific microstructure of the superconducting YBCO foams is required. To obtain a set of reliable data, YBCO foam samples were investigated using optical microscopy, scanning electron microscopy and electron backscatter diffraction (EBSD). A variety of parameters including the size and shape of the cells and windows, the length and shape of the foam struts or ligaments and the respective intersection angles were determined to better describe the real foam structure. The investigation of the foam microstructures revealed not only the differences to the original polymer foams used as base material, but also provided further insights to the infiltration growth process via the large amount of internal surface in a foam sample.
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Chen, Zhu, Ramadan Mohammed Ahmed, Stefan Z. Miska, Nicholas E. Takach, Mengjiao Yu i Mark B. Pickell. "Rheology and Hydraulics of Polymer (HEC) Based Drilling Foams at Ambient Temperature Conditions". SPE Journal 12, nr 01 (1.03.2007): 100–107. http://dx.doi.org/10.2118/94273-pa.
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Summary An experimental investigation on polymer-based drilling foams was carried out. Rheology tests were performed with foams that have different concentrations of hydroxylethylcellulose (HEC) and 1% commercial surfactant. Experiments were conducted in a large-scale flow loop that permits foam flow through 2-, 3-, and 4-in. pipe sections, and a 6×3.5-in. annular section. During the experiments, frictional pressure losses across the pipe and annular sections were measured for different gas/liquid flow rates, polymer concentrations (0, 0.25, and 0.5%), and foam qualities (70, 80, and 90%). Significant rheological variations were observed between aqueous foams containing no polymers and polymer-thickened foams. Experimental data show three distinct flow curves for the 2-, 3-, and 4-in. pipe sections, which indicates the presence of wall slip. The Oldroyd-Jastrzebski approach was used to calculate the wall slip velocity and determine the true shear rate. It has been found that wall slip decreases as the foam quality or polymer concentration increases. Two foam hydraulic models, which use slip-corrected and slip-uncorrected rheological parameters, have been proposed. These models are applicable for predicting pressure loss in pipes and annuli. Model predictions for the annular test section are compared with the measured data. A satisfactory agreement between the model predictions and measured data is obtained. This paper will help to better design foam drilling and cleanup operations. Introduction The use of drilling foams is increasing because foams exhibit properties that are desirable in many drilling operations. In practice, aqueous and polymer-based foams have been used with commercial success. However, drilling-foam rheology and hydraulics are still not sufficiently understood to minimize the risk and costs associated with foam drilling. It is generally accepted that the addition of polymers to the liquid phase affects the viscosity and stability of foams. However, the degree to which the bulk properties of drilling foams are enhanced by polymers has not been well understood and is difficult to predict. For safe and economical foam drilling, accurate knowledge of bottomhole pressure is essential. However, foam rheology and pressure drop predictions are not accurate enough to provide adequate hydraulic design information such as equivalent circulation density. This problem is more pronounced when polymers are added, because the apparent foam viscosity of polymer-thickened foams can be significantly higher than aqueous foams. It becomes apparent that there is a need for polymer foam rheological characterization in order to improve the knowledge of foam rheology and hydraulics. Foam rheological characterization was carried out using large-scale, single-pass pipe viscometers (composed of 2-, 3-, and 4-in. pipe sections). Foam qualities were varied from 70 to 90%. Test pressure and temperature were 100 psig and 80°F. Two foam hydraulic models were considered, assuming both no-slip condition at the wall and slip condition at the wall. The first model assumes no-slip boundary conditions in both pipes and annulus. By assuming no slip condition at the wall, slip-uncorrected foam rheological parameters were obtained from the pipe viscometer measurements. It has been found that if we plot friction factors vs. Reynolds numbers for all test data, regardless of pipe diameters, foam qualities, and flow rates, a single curve is obtained. This curve is similar to that obtained for incompressible fluid flow. Pressure drop in the annulus is calculated with the proposed model, and satisfactory predictions are obtained. The second model is based on the assumption that there is wall slip in both pipes and annulus. Rheological parameters and wall-slip coefficient corrections were first obtained using Oldroyd-Jastrzebski approach. The annular pressure losses are predicted based on slip-corrected rheological parameters and wall-slip coefficient correlations.
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Adnan, Srihanum, Tuan Noor Maznee Tuan Ismail, Norhayati Mohd Noor, Nik Siti Mariam Nek Mat Din, Nurul ‘Ain Hanzah, Yeong Shoot Kian i Hazimah Abu Hassan. "Development of Flexible Polyurethane Nanostructured Biocomposite Foams Derived from Palm Olein-Based Polyol". Advances in Materials Science and Engineering 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/4316424.
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This study examined the effect of organoclay montmorillonite (OMMT) on the mechanical properties and morphology of flexible polyurethane/OMMT nanocomposite (PU/OMMT) foams prepared from petroleum- and palm olein-based polyols. Palm-based PU foams exhibited inferior mechanical strength as compared to neat petroleum PU foams. However, addition of OMMT significantly improved the foams strength of flexible polyurethane/OMMT nanocomposite foams prepared from palm olein-based polyol (PU bionanocomposite foam). The morphology analysed by scanning electron microscopy (SEM) showed that the cell size of the foam decreased with increasing OMMT content. PU bionanocomposite foam with 5 wt% of OMMT had the most improved tensile (63%) and tear (48%) strengths compared to its neat counterpart. Transmission electron microscopy (TEM) revealed the exfoliated structure of the respective foam. It was concluded that OMMT improved mechanical properties and morphology of PU foams.
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Auguścik-Królikowska, Monika, Joanna Ryszkowska, Maria Kurańska, Marta Wantulok, Michał Gloc, Leonard Szczepkowski, Katarzyna Dąbkowska-Susfał i Aleksander Prociak. "Composites of Open-Cell Viscoelastic Foams with Blackcurrant Pomace". Materials 14, nr 4 (16.02.2021): 934. http://dx.doi.org/10.3390/ma14040934.
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Taking into account the circular economy guidelines and results of life cycle analyses of various materials, it was proposed to use a blackcurrant pomace filler in the production process of viscoelastic polyurethane (PUR) foams intended for application as mattresses, pillows, or elements for orthopedics. Open-cell viscoelastic PUR foams containing 10–60 per hundred polyols (php) blackcurrant pomace were prepared. It was found that after introducing the filler to the PUR foam formulation, the speed of the first stage of the foaming process significantly decreases, the maximum temperature achieved during the synthesis drops (by 30 °C for the foam containing 40 php of filler compared to unfilled foam), and the maximum pressure achieved during the synthesis of foam containing 20 php is reduced by approximately 57% compared to the foam without filler. The growth time of the foams increases with increasing the amount of introduced filler; for the foam containing 60 php, the time is extended even by about 24%. The effect of the filler on the physical, morphological, mechanical, and functional performances of PUR foam composites has been analyzed. The use of 60 php as the filler reduced the hardness of the foams by approximately 30% and increased their comfort factor from 3 to 5.
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Chen, Shu Yan, Qing Feng Hou, You Yi Zhu, Wen Jun Li i Zhi Dong Chang. "Foam Stability of Mixed System of Fluorocarbon and Hydrocarbon Surfactants: Effect of Polymer and Oil". Advanced Materials Research 803 (wrzesień 2013): 85–89. http://dx.doi.org/10.4028/www.scientific.net/amr.803.85.
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The foaming property of the aqueous mixtures of a fluorocarbon surfactant (FC) and a hydrocarbon surfactant (AOS) had been investigated. And the influence of polymer and oil on foam stability was studied systematically. Experimental studies indicated that AOS and FC surfactants had good cooperative effect. The foam stability could be remarkably improved with polymer and oil would impact the foam stability greatly. Mechanism on interaction between foam and oil for experimental foam systems was also studied quantitatively based on spreading coefficient. The effect of oil on the stability of polymer enhanced foams could not be fully understood by spreading coefficient. The increasing in viscoelasticity of foam films would play a key role in the stability improvement for polymer enhanced foams.
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SUN, QICHENG, LIANGHUI TAN i GUANGQIAN WANG. "LIQUID FOAM DRAINAGE: AN OVERVIEW". International Journal of Modern Physics B 22, nr 15 (20.06.2008): 2333–54. http://dx.doi.org/10.1142/s0217979208039514.
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Liquid foams are concentrated dispersions of gas bubbles in a small amount of surfactant solution, which are perpetually out of equilibrium systems. The process of liquid draining through networks of Plateau borders in a fresh foam is so-called foam drainage, as a result of both gravitational and capillary forces, which has great effect on the stability of foams. From the view of foam physics and dynamics, this paper briefly introduces foam structure and major lifetime limiting factors of foam. The substantial progress on the theory of drainage, measuring techniques for liquid fractions, drainage in both one dimension and two dimensions, and drainage in microgravity circumstances are overviewed throughout. Remaining tasks are discussed and a multiscale methodology for foam drainage is proposed for future investigations.
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Guo, Chao Qun, Tian Yao Wang, Tian Xiang Yuan, De Lin Ma, Yun Zhou i Xiao Qing Zuo. "Quasi-Static Axial Compression Behavior and Energy Absorption Evaluation of Steel Foam-Filled Tubes". Materials Science Forum 993 (maj 2020): 863–68. http://dx.doi.org/10.4028/www.scientific.net/msf.993.863.
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The aim of this paper is to study the quasi-static axial compressive performance of newly developed steel foam-filled tubes (SFFTs). The energy absorption capability of steel foam-filled tubes was assessed. The results show that steel foam-filled tubes collapse in the axisymmetric-concertina deformation mode. The plateau stress of the plastic deformation of the steel foam-filled tubes decreases with the increase of porosity of steel foams, and is significantly higher than the sum of the identical steel foam and aluminum tube. The absorbed energy per unit volume of the steel foam-filled tubes is 8%~ 15% higher than the sum of those of identical aluminum tubes and steel foams with porosity ranging from 65% to 80%.
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Lisiecki, Janusz, Dominik Nowakowski i Piotr Reymer. "Fatigue Properties of Polyurethane Foams, with Special Emphasis on Auxetic Foams, Used for Helicopter Pilot Seat Cushion Inserts". Fatigue of Aircraft Structures 2014, nr 6 (1.06.2014): 72–78. http://dx.doi.org/10.1515/fas-2014-0006.
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Abstract Seat cushion inserts in military helicopters crew seats, as suggested by the helicopters manufacturers, are made of traditional polyurethane foams. Elastic polyurethane auxetic foams are materials that exhibit different utility properties compared to traditionally used polyurethane foams, such as polyether or polystyrene foams. All the differences result from the primary physical property of elastic polyurethane auxetic foams which is a negative Poisson’s ratio. Auxetic materials are characterized by better utility properties than conventional foam materials – they can potentially increase safety in the event of a crash and offer higher comfort during regular use. Application of auxetic materials as seat cushion inserts would also decrease harmful health effects of vibrations. This paper presents the results of the fatigue tests carried out on different foam samples by pressing an indenter into the foams' surface that was much larger than the indenter’s surface. A maximum value of the load used during the test was within a defined range in every fatigue cycle. In order to test 150×150×50 mm foam samples a special indenter was designed and manufactured according to the PN-EN ISO 3385 and PN-EN ISO 2439 standards. The indenter’s dimensions were consistent with the standards in relation to the tested foams' size. The fatigue tests of both conventional and auxetic foams were carried out according to the above given standards by applying 80,000 load cycles at 70 cycle/min frequency. Tests of viscoelastic foam and multilayer foam specimens, for which the upper layer was made of viscoelastic foam, were carried out according to the ASTM D 3574 standard applying 12,000 load cycles at 10 cycle/min frequency. All the tests were carried out using the MTS 370.10 strength testing machine. Changes in thickness and density were determined throughout the tests. Moreover, the influence of the volumetric compression ratio on the fatigue properties of auxetic foam samples and the dependence of foam deflection on the number of cycles were examined. Finally, the test results obtained for conventional and auxetic foams were compared and discussed.
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Koksharov, A. V., S. I. Osipenko i E. V. Gaynullina. "Study of the thermal stability of foam of different expansion ratio". Pozharovzryvobezopasnost/Fire and Explosion Safety 29, nr 3 (19.07.2020): 103–10. http://dx.doi.org/10.22227/pvb.2020.29.03.103-110.
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Introduction. Currently, the industry produces a wide range of foam generators to produce fire-extinguishing foams, and the foams they produce differ significantly in their expansion ratio and, consequently, fire resistance. Since heat fluxes have the main destructive effect on the foam, the purpose of this paper is to establish the patterns of destruction of foam of different expansion ratio when heated.Methods of research. The foam with expansion ratio from 7.5 to 80 was used for the tests. It was obtained by mechanical beating of 6 % solution of foaming agent PO-6RZ. The thermal stability of the foam was studied when the heat flow from the gas burner flame affects the foam layer. During the experiment, the change in the height of the foam column in time was recorded.Results and Discussion. The results of measurements, presented in the form of dependence of foam layer destruction rate on time, quantity of released liquid phase on 1 m2·s, dependence of foam layer destruction rate on its density allowed revealing a number of patterns. The destruction rate of foam with an expansion ratio of up to 30 remains constant throughout the entire duration of thermal exposure. As the foam expansion ratio increases, the rate of destruction at the initial stage of heat flux exposure increases. With a foam expansion ratio of more than 50, there is initially a sharp increase in the rate of destruction, which subsequently decreases as the foam column decreases. In the conditions of the experiment, the best characteristics were shown by the foam with an expansion ratio of 50, because in the foam with a smaller expansion ratio the syneresis makes a significant contribution to its destruction, and the foams with a larger expansion ratio are destroyed by the mechanical effect of convective flame flows.Conclusion. The study of the foam destruction patterns under thermal impact allowed establishing the fact that its destruction is limited by the rate of impoverishment of the upper layers with liquid.
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Bao, Zhi Ming, Xian Zhong Zhang, Xue Cheng Fu i Ying Nian Hu. "Research Progress in Biodegradation of Firefighting Foam". Advanced Materials Research 518-523 (maj 2012): 817–20. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.817.
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Firefighting foam is highly effective in suppressing and extinguishing liquid fuel fires. As the concern of its environmental impacts growing, it is necessary to evaluate its biodegradation in the environment. This article briefly introduces the concept, classification, and the main component of firefighting foam. Also the principle, general process, basis mechanism of the biodegradation of firefighting foam are discussed. There is no standard test methods focusing on the biodegradation of firefighting foam, also relative research and reports are less. Limited research data abroad shows that the biodegradability of some foams are very low, and protein based foams may not easier to biodegrade than synthetic based foams.
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Xiong, Jian Yu, Yun Cang Li, Yasuo Yamada, Peter D. Hodgson i Cui E. Wen. "Processing and Mechanical Properties of Porous Titanium-Niobium Shape Memory Alloy for Biomedical Applications". Materials Science Forum 561-565 (październik 2007): 1689–92. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.1689.
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Ti-26 at.%Nb (hereafter Ti-26Nb) alloy foams were fabricated by space-holder sintering process. The porous structures of the foams were characterized by scanning electron microscopy (SEM). The mechanical properties of the Ti-26Nb foam samples were investigated using compressive test. Results indicate that mechanical properties of Ti-26Nb foam samples are influenced by foam porosity. The plateau stresses and elastic moduli of the foams under compression decrease with the increase of their porosities. The plateau stresses and elastic moduli are measured to be from 10~200 MPa and 0.4~5.0 GPa for the Ti-26Nb foam samples with porosities ranged from 80~50 %, respectively.
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Hu, Xiangfang, i Zong Meng. "An overview of edible foams in food and modern cuisine: Destabilization and stabilization mechanisms and applications". Comprehensive Reviews in Food Science and Food Safety 23, nr 1 (19.12.2023): 1–30. http://dx.doi.org/10.1111/1541-4337.13284.
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AbstractFoam, as a structured multi‐scale colloidal system, is becoming increasingly popular in food because it gives a series of unique textures, structures, and appearances to foods while maintaining clean labels. Recently, developing green and healthy food‐grade foaming agents, improving the stability of edible foams, and exploring the application of foam structures and new foaming agents have been the focus of foam systems. This review comprehensively introduces the destabilization mechanisms of foam and summarizes the main mechanisms controlling the foam stability and progress of different food‐grade materials (small‐molecular surfactants, biopolymers, and edible Pickering particles). Furthermore, the classic foam systems in food and modern cuisine, their applications, developments, and challenges are also underlined. Natural small‐molecular surfactants, novel plant/microalgae proteins, and edible colloidal particles are the research hotspots of high‐efficiency food‐grade foam stabilizers. They have apparent differences in foam stability mechanisms, and each exerts its advantages. However, the development of foam stabilizers remains to be enriched compared with emulsions. Food foams are diverse and widely used, bringing unique enjoyment and benefit to consumers regarding sense, innovation, and health attributes. In addition to industrial inflatable foods, the foam foods in molecular gastronomy are also worthy of exploration. Moreover, edible foams may have greater potential in structured food design, 3D/4D printing, and controlled flavor release in the future. This review will provide a reference for the efficient development of functional inflatable foods and the advancement of foam technologies in modern cuisine.
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Zhao, Wuling, Qiupeng Hou i Xiwen Wang. "The influence of gas diffusion mechanisms on foam stability for foam forming of paper products". BioResources 14, nr 4 (29.10.2019): 9893–903. http://dx.doi.org/10.15376/biores.14.4.9893-9903.
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Foam forming is an innovative process for papermaking that yields various paper products with excellent formability and porosity. The stability of the foam is a critical factor in foam forming technology. The effects of different surfactants and gases (N2 and CO2) on the ability of the foams to coalesce and the stability of the foams were studied. The properties of the liquid film were investigated via high-speed camera observation and infrared spectrum. The CO2 foam was less stable than the N2 foam under the same conditions, especially for the polyvinyl alcohol surfactant. The infrared spectra and high-speed camera observation showed that the main factor that resulted in CO2 foam instability was the bubble coalescence caused via the gas diffusion in the foam column, although the process of liquid film thinning was performed simultaneously. The greater the liquid film permeability coefficient of the foam, the easier the gas was able to spread throughout the liquid film. Foam forming technology will likely be employed in many potential pulp and papermaking mill processes.
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Cao, Zhuo Kun, Huan Liu, Jin Jing Du i Guang Chun Yao. "Preparation of High Performance Aluminum Foam Using Carbon Fibers as Stabilizing Additive". Advanced Materials Research 308-310 (sierpień 2011): 53–57. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.53.
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Carbon fibers are used as novel stabilizing additives for aluminum foams production at the aim of manufacturing metallic foams of high mechanical performance. The effect of carbon fiber fraction on the foam structure and mechanical property is studied in the present paper. Results shows that the change in foam structure can be slowed down by increasing fiber fraction, which would led to more stable foam. The yield strength of aluminum foams increase with fiber fraction, but the foams are also getting brittle. High performance aluminum foams can also prepared by using aluminum alloy as start material, and the resulting foams show much higher compressive strength than that of commercial aluminum foams.
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Yang, Si Yi, Er Tuan Zhao i Yu Kun An. "Research on Manufacturing the Metal Foams with Regular Cells by 3D Printing". Advanced Materials Research 1120-1121 (lipiec 2015): 1233–37. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.1233.
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In the paper the methods of designing and manufacturing of the metals foam with regular cells are researched. The software models of metals foam are designed by CAD. The models are transmitted into 3D printing machine to manufacture foam framework. The metal foams with regular cells and fixed porosities are manufactured by chemical plating, electric plating and investment cast. According to the applications the structures of metal foams can be designed to control sizes, shapes and distribution of pores, porosities, density and to control the properties of metals foam, which can satisfy various demands of applications. Nickel foam with regular cells is designed and manufactured by this method.
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Wang, Ying Wu, Xiao Qing Zuo i Xian Ning Chen. "Preparation and Sound Absorption Property of Al-Si12 Alloy Foam Core Muffler". Advanced Materials Research 183-185 (styczeń 2011): 1687–91. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.1687.
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Al-Si12 alloy foams were fabricated by filtration method, and the Al-Si12 alloy foam core mufflers were made by using the fabricated Al-Si12 alloy foams. The preparation and sound absorption property of Al-Si12 alloy foam core muffler has been studied. The results show that sound absorption property of Al-Si12 alloy foam core muffler increases with the decreasing of pore diameter and the widening of the pore diameter range of Al-Si12 alloy foam core. Being superior to conventional sound-absorbing materials core mufflers, Al-Si12 alloy foam core muffler especially fits in noise control in hot, wet, and open-air environments.
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Shutov, F. A., i V. V. Ivanov. "Foams Based on Phenolic and Urea-Formaldehyde Resins Mixtures and their Applications for Heat Insulation of Pipelines. 5. Investigation of Ageing of Phenolic Foams during Long-term Exposure to High Temperature". Cellular Polymers 4, nr 1 (styczeń 1985): 27–41. http://dx.doi.org/10.1177/026248938500400104.
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The specificity of long-term ageing of phenolic foam in the heat insulation of pipe lines is discussed. Apparent density distribution of foam across the thickness of the foam layer affected the service time of foam insulation in real conditions of application. After long-term exposure (up to 4000 h at 100–200° C) compressive strength of foams was studied. Assuming that the time-temperature dependences of foams follow the Arrhenius law, the duration of foam was predicted and compared with experimental data. Thermogravimetric analysis was applied, and kinetic constants of long-term ageing were calculated. Other properties, i.e. electrical properties and water sorption, were also studied.
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Wollmann, J. C. "Sclerosant foams". Phlebologie 39, nr 04 (2010): 208–17. http://dx.doi.org/10.1055/s-0037-1622317.
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SummaryNumerous ways of transferring detergent type liquid sclerosants into foam have been described. Out of all techniques, the three most commonly used around the world were selected. Sclerosant foams prepared with different agents and protocols were analyzed in detail, and their rheologic properties were assessed. Some of the results are presented in this review. Results: It is evident that the the material for foam production plays an important role for foam stability, and – connected to this – maybe also for efficacy and safety. Therefore, material that ensures acceptable foam quality should be used exclusively. Out of a huge number of possibilities, the material described in this study was found most suitable. This ensures minimal reduction of foam quality delivered into the vein. Foams considered instable are not clinically ineffective. They have a greater efficacy than the corresponding liquid agent. Foams considered stable seem to need lower injection volumes to have the same or better physical behaviour. Conclusion: Since higher volumes of sclerosant foams are correlated with more side effects, always the smallest effective volumes of foams of appropriate quality are justified.
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Sheng, Youjie, Hanling Zhang, Li Ma, Zhenping Wang, Die Hu i Shanwen Zhang. "Rheological Properties of Gel Foam Co-Stabilized with Nanoparticles, Xanthan Gum, and Multiple Surfactants". Gels 9, nr 7 (30.06.2023): 534. http://dx.doi.org/10.3390/gels9070534.
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Gel foam has the advantages of gel and foam and shows good prospects for applications in the fields of fire prevention and extinguishing. Rheology has a significant impact on the application of gel foam, but there is little related research. In the present study, hydrophilic silica nanoparticles (NPs) and water-soluble polymer xanthan gum (XG) were combined with fluorocarbon surfactant (FS-50) and hydrocarbon surfactant (APG0810) to create gel foam. The foaming ability and foam drainage were evaluated. The gel foam’s rheology, including its flow behavior and viscoelasticity, was systematically investigated. The results show that the foaming of the FS-50/APG0810 mixture decreases but the foam drainage increases in the presence of NPs and/or XG. All of the foams belong to the category of non-Newtonian fluids with shear thinning behavior. The flow curves of the foams are consistent with the Cross model. The presence of XG/NPs enhanced the foam viscoelasticity of the FS-50/APG0810 mixture. The silica NPs showed a better ability to enhance foam viscoelasticity but a worse ability to stabilize the foam compared to XG. This research can offer theoretical support for the industrial usage of gel foam.
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Dhoke, Rujuta, Abhishek Ojha, Ashutosh Kr Chaudhary i RP Vijayakumar. "Influence of carbon nanotubes on the properties of biopolyol based polyurethane foams". Cellular Polymers 40, nr 2 (20.01.2021): 73–86. http://dx.doi.org/10.1177/0262489321989005.
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Biopolyols were obtained from liquefaction of sugarcane bagasse and rice husk. Acid and hydroxyl numbers were determined for estimating the polyol value of the liquid products. These prepared biopolyols were mixed with the commercial polyol for the preparation of polyurethane foam (PU). To study the effects of biopolyol on properties of PU foam, various ratios of biopolyol to commercial polyol were used. It was observed that the density and foaming time of the PU foam increases with the increase in biopolyol content. The calculated Isocyanate index showed that sugarcane bagasse polyol can be used to make flexible foam and that rice husk can be used to make rigid foam. Foaming times and full rise times increased with increase in the biopolyol content. The Fourier-transform infrared spectroscopy (FTIR) spectra of prepared foams showed the characteristic peaks related to PU foam. The morphological studies were carried out using scanning electron microscopy (SEM). Thermal conductivity tests proved that the synthesized PU foams can be used as insulating materials. Further, PU foams were also prepared with the incorporation of carbon nanotubes (CNTs) in the polyol. The densities, thermal conductivities and SEM analysis of PU foams with and without carbon nanotubes were compared.
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Wu, Ju Ying, Jing Hui Fan, Yu Hong Huang, Zhang Kai i He Fang. "Study on Adhering Technology of Silicone Foam Surface". Advanced Materials Research 800 (wrzesień 2013): 440–46. http://dx.doi.org/10.4028/www.scientific.net/amr.800.440.
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Several purpose-designed adhering ways have been used for silicone adhesive adhering on silicone foam surface. The stress-strain and relaxing properties of the adhered and non-adhered silicone foam have been tested. By contrasting the effect of each adhering way to the silicone foams property and considering each adhered silicone foams SEM profile photo we found out the better adhering way C for silicone foam adhered by silicone adhesive. This adhering way C has small transmissibility, good compatibility, and little effect to the silicone foams property, so it can fit silicone foams applying demand.