Papers by Keyword: Cell Structure

Abstract: Open-cell aluminum foams with spherical cells have great potential application due to their reliable structural and functional performance. However, a problem of poor cell connectivity always arises during fabrication. Three precursor designs were explored to optimize the cell structure. The results showed that the lack of the treatment of the space holders caused poor cell connectivity and a lower porosity, which could be resolved by introducing alcohol as a binder or hot-pressing space holders in precursor designs. Nevertheless, a poor fluid of the granules in the former had a negative effect on porosity improvement, whereas the latter created a precursor with strong bonding between the granules with good flow characteristics and led to a significant improvement in cell connectivity and porosity. This work could provide an approach to designing precursor structures in order to tailor the structure of the final open-cell aluminum foam.

Abstract: EVA/Poplar wood powders composite foaming materials were prepared from etheylen-vinyl acetate-copolymer (EVA) as matrix, poplar wood powders as filler, azodicarbonamide (AC) as foaming agent, dicumyl peroxide (DCP) as cross-linking agent through the method of compression molding foaming. EVA with 15% VA (EVA 15) was chosen as foaming matrix resin by the rotational rheometer. The results showed that an optimum foaming effect had been gained when the AC and DCP were 11 wt% and 0.9 wt%, respectively. And under the condition, the foam density ascended with the increase of poplar wood powders content, when the content arrived to 30%, the resilience reached up to a maximum of 90.1%. The foam cellular structure was researched by SEM, and it showed that when poplar wood powders content was below 30%, the foam holes appeared round or oval, the holes’ size were rather evenly. And the foam cells became more and more unevenly, even collapsed when poplar wood powders up to the content of 40%.

Abstract: The mechanical properties of methyl vinyl silicone rubber foam materials with different cell diameters of the spherical cell structure were investigated. The results showed that the cell diameter had significant effects on the mechanical properties,the foam materials with cell diameter range 300~450μm had the best compression stress property and stress-relaxation property. The changing of cell shape of the spherical cell foam materials in the process of dynamic compression were analyzed by using micro focus uCT technology, with obtaining the parameters of cell volume, porosity and so on.

Abstract: Thermal insulation materials are among the simplest ways of decreasing heat loss in the buildings. When insulation materials are installed in the walls, floors and roof of a building to prevent heat loss from the building, materials must be used with the appropriate structural and thermal properties. In this paper, a laboratory test of the thermal conductivity and cell structure of building insulation materials was conducted. From the experiment results, the correlation expression between thermal conductivity and density was derived. In the case of the insulation materials that were made of expanded polypropylene (EPP), as the density increased, the thermal conductivity tended to decrease; and in the case of ethylene-vinyl acetate co-polymer (EVA) and polyethylene (PE), as the density of the insulation materials increased, the thermal conductivity tended to also increase.

Abstract: In this paper the closed-cell sponge of chloroprene rubber(CR) were produced by foaming agent Azodicarbonamide (AC) and Oxybis (benzene sulfonyl) hydrazide (OBSH). The blend blowing agent AC/OBSH was more effective than the pure AC as it could produce chloroprene foam with greater cell porosity, more uniform and better cell distributions. The CR foam prepared with AC/OBSH had better tensile strength and tear strength than pure AC, but higher Shore C hardness. The Polyethyene glycol (PEG) modified Zinc Oxide (ZnO) could accelerate curing and foam process simultaneously. Increase the content of PEG, CR foam has bigger swell ratio, smaller cell size, and better softness.

Abstract: In this paper,bamboo pulp was chosen as the raw material on the basis of the researching on the structure and properties of the resource-rich bamboo fibers, the foaming material using the bamboo pulp and other assistants were obtained.It developed bamboo's new applied area and supplied the cushioning industry with a new choice.The best reagent and the optimal ratio of the various components have been identified by the quality evaluation system. Studied on the high efficiency and no polluting foaming mechanism to determine the parameter of foaming technics. Determined the interior adhesive and exterior disposal.Conducted the structural analysis and mechanical properties testing, and in compare with the performance of common cushioning material,we know that: Material has a certain buffer performance and for the packing of the products with small shock fragility.

Abstract: The effect of kaolin content on the cell structure of PS foam and the correlation between the cell structure and the physical properties were evaluated in this work. The kaolin as a nucleating agent did facilitate the cell nucleation. The cell structures were apparently enhanced with increasing kaolin content. In addition to facilitating nucleation, the kaolin confined the motion of chain segments of the matrix polymer, which contributed to the change in cell structure by confining cell growth and cell coalescence to some extent. The foam with smaller cell size and larger cell density absorbed more energy, hence the impact strength increased remarkably with decreasing cell size and increasing cell density.

Abstract: In this paper the formation and growth of bubbles during the melt foaming process are studied from microcosmic aspect. The forming process of liquid film between two neighboring bubbles is also analyzed. According to the cavity effect of ultrasonic wave, the effect of ultrasonic wave on the fragmentation of cell structures of aluminum foam is investigated. Results show that the effect of ultrasonic wave on the cell structure fragmentation decreases with the increase of the distance from the ultrasonic wave source to the cell structure. Therefore, a new concept, namely aluminum foam of biomimetic gradient structure, is proposed.

Abstract: The cell-structure of highly porous aluminum material prepared by foaming of aluminum alloy melt with titanium hydride was investigated nondestructively with fine-focus X-ray 3D-CT at several interrupt steps during slow compressive deformation. The foamed highly porous aluminum has anisotropic shape of each cell inevitably because of gravity force during solidification of foamed material and mechanical properties especially the dependence on the deformation direction of highly porous aluminum is analyzed well from the size and shape of each void composing the porous material. The statistic anisotropic distribution of these form factors such as three axial lengths and directions at the time of ellipsoidal approximation of each cell was found to be less important to improve the mechanical properties of this type of material.

Abstract: The dislocation substructure that appears in deformed metals and alloys have been extensively investigated in the past by transmission electron microscopy (TEM). They are known to form a broad variety of microstructures. These substructures are characterized by three main parameters, namely the density of the dislocations that are trapped in the tangles, their degree of patterning and the misorientation between the cells. The aim of the present work is to investigate the relationship between these features and the mechanical properties of the material.