Papers by Keyword: Porous

Abstract: Chitosan (CS) and gelatin (G) both have good biocompatibility and biodegradation, qualifying them for use in tissue engineering. In this study, CS and G are blended with different ratios to make the mixture solution, and then freeze-dried to form three-dimensional porous CS/G bone scaffolds. The surface, cross-section, porosity, and pore size of the resulting bone scaffolds are observed and analyzed. According to the experimental results, the addition of gelatin gives the CS/G bone scaffolds morphology with few pores. As can be seen from SEM observation, there are linear pores in the cross-section. In addition, with a larger quantity of gelatin, the CS/G bone scaffolds have a lower porosity.

Abstract: After dissolve PVDF in DMF, porous PVDF beads were prepared by water assistant. The porous beads were better crystallized and possessed greater relative surface than ordinary PVDF. The results suggested that the relative surface of PVDF reach 6.53m2/g while the dripping speed was 0.95ml/min. The material could rise to the modulator to fabricate nanometer fiber polymers.

Abstract: Ca₃Co₄O₉ powders were synthesized by a solid-state reaction method. Porous Ca₃Co₄O₉ ceramics with parallel sheet shaped pores were prepared by a template sacrifice method using epispastic polystyrend (EPS) hollow spheres as the templates. During compaction of the green body, the EPS hollow spheres change into EPS discs due to the pressing force. After sintering, the pores in the Ca₃Co₄O₉ ceramics are sheet shaped, well distributed and parallel to the pressing surface of compaction. The value of ZT merit of the porous Ca₃Co₄O₉ sample obtained with 10 wt% EPS spheres is 0.0489. It was found that the ZT merit value can be improved by changing the density of sample to achieve a high ratio of electrical conductivity to thermal conductivity.

Abstract: Synthesis of porous silica via styrene natural rubber sacrificial template is investigated. This research is divided into three steps which are synthesis of Styrene Natural Rubber (SNR), SNR/silica film formation and formation of porous silica. The synthesis of SNR is obtained via emulsion polymerization which involves styrene as monomer and Deproteinized Natural Rubber (DPNR) latex as based materials. SNR is used as sacrificial template to produce porous silica. The amount of silica loading and mixing method were varied during formation of SNR/silica film. Calcination is use to completely remove styrene and latex, leaving behind a new material with porous structure. It was found that the increasing of silica loading will enhanced the porosity of the structure and the best mixing method can be obtained using shaker instead of mechanical stirrer and magnetic stirrer. The porous structure can be observed via Scanning Electron Microscopy (SEM).

Abstract: The need for bone repair has increased as the population ages. However, currently, the bone grafts still have some disadvantages, such as low compressive strength and porosity, which limit their use. In order to solve these disadvantages, in this study, the porous beta-tricalcium phosphate (β-TCP) anorganic bone graft were prepared from healthy bovine cancellous bone by cell-free, defat and twice calcinations. X-ray diffraction (XRD) was used to investigate the chemical composition of the bone graft. And the morphology, porosity and mechanical strength of the bone graft were also evaluated. The results showed that most constituent of the bone graft was β-TCP. In addition, the bone graft scaffold exhibited the macro and micro porous structure and the porosity was 57.63%, just as the nature cancellous bone. The compressive strength was 4.47±0.63MPa. Above all, the porous β-TCP anorganic bone graft not only has similar chemical composites as the nature cancellous bone, but also it can effectively retain the porous structure of natural cancellous bone and provides optimal channels for the ingrowth of new bone and blood vessels.Therefore, the porous β-TCP anorganic bone graft is a potential biomaterial in bone tissue engineering.

Abstract: This paper studies the different porosity of porous medium how to affect the flow pressure field under the conditions of same inlet velocity and fiber diameter by CFDmethod. Geometric model of the catalytic converter has been established and meshed by the pre-processing tool of FLUENT. The flow pressure simulation filled contours and the curve of center line static pressure distribution of the fiber porous material show that in the case of other conditions remain unchanged, the less the porosity of the fiber porous material, the higher the inlet pressure and the more the pressure loss of the porous material. The more porosity of fiber is beneficial to exhaust catalytic reaction.

Abstract: This paper studies the different porosity of porous medium how to affect the flow velocity field under the conditions of same inlet velocity and fiber diameter by CFD method. Geometric model of the catalytic converter has been established and meshed by the pre-processing tool FLUENT. The flow speed simulation filled contours and velocity distribution curve of the fiber porous material show that reducing properly the porosity may improve the uniformity of the velocity in Y and Z direction of the porous material. The less porosity is beneficial to exhaust catalytic reaction.

Abstract: Hydraulic resistance of water flow in the xylem is mainly caused by Pits. Pits between vessels play an important role in the water transport of plant. The pit membrane worked as porous, the water flow through pit is modeled using CFD(Computational fluid dynamics) approach of low k-ε turbulence. Consiedered the deflection of homogeneous membrane affected by pressure difference, the pit hydraulic resistance calculated according to simulation results is consisent with hydraulic resistance value from direct measurements, which indicated that the model can provide reliable estimation the flow of water through pit.

Abstract: Porous ceramics can be produced by adding starch (corn, potato) and protein (animal or vegetable) to raw material as pore forming element. In this study, titanium dioxide ceramics were formed by vegetable protein consolidation. Soybean was chosen as the binding agent and pore forming. The samples, which were produced in cylindrical shape, had the following processing: material mixture, gelling, drying, pre-sintering and sintering. Heated platinum microscopy were performed by using suspensions with different compositions in order to verify protein gelling capacity and better know the temperature in which this process occurs. The samples were characterized by apparent porosity and roughness measurement. Besides, imaging by light microscopy was also performed in order to determine the sample morphology and porosity.

Abstract: Silicon carbide is used to produce abrasive and high-temperature structural ceramic materials due to its mechanical and chemical properties. The possible applications of porous silicon carbide ceramics are diesel engines catalysers and molten metal filters. In the last years the starch gained importance as a pore-forming and consolidation agent, due to it is environmental friendly and easily processing. The current work uses starch (corn, rice and potato) as pore forming and consolidation agent. The samples sintered at different sintering times were characterized by density and microstructure (XRD, SEM). The results show that the samples presented porosity between 20 and 40% and the microstructures obtained is homogeneous with a pore size similar to the starch particle added.