• Elastomers and Composites
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• v.51 no.1
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• pp.24-30
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• 2016

Sole in the footwear usually modified with foaming agent on the polymer resin to improve the lightweightness and crush-cushion effect. In this study, we investigated rheological properties for polymer resin filled with the different type and concentration of foaming agent, capsule type foaming agent and organo-chemical foaming agent, under the time sweep test. Curing times of each polymer resin with different kind of foaming agent are delayed than reference material (epoxy resin with curing agent). In case of adding capsule type foaming agent, however, there is appropriate concentration to reduce the curing time, relatively. When foaming agent is activated, foaming force inflates the sample in contrast to condensation force of curing and then axial normal force develop to the (+) direction. Interestingly, by increase concentration of foaming agent, there is a specific point to break down the axial normal force development. The reason for this phenomenon is that coalescence of foams induce the blocking of axial normal force development.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.419-420
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.491-495
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• 2004

The industries use polymer materials for many purposes for they have many merits. The costs of these materials take up too great a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2$, $N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. This characteristic of microcellular foaming process has influenced by cell morphology. The cell morphology means cell size and cell density. The cell morphology has influenced by many factors. The examples of factor are pressure drop rate, foaming temperature, foaming time, saturation pressure, saturation time etc. Among their factors, pressure drop rate is the most important factor for cell morphology in microcellular foaming injection molding process. This paper describes about the cell morphology change in accordance with the pressure drop rate of microcellular foaming injection molding process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.364-368
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• 2004

Micro Cellular Plastics create a sensation at polymer industrial for lowering product cost & overcoming a lowering of mechanical intensity. This research based on the experiment of sound absorption & transmission characteristics inquire into acoustic property of Micro Cellular Plastics. This experiment clarify the change of cell foaming rate for foaming time and the change of sound absorption & transmission for foaming rate.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.1
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• pp.73-80
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• 1988

This study was performed to obtain the basic data which can be applied to use of foaming mortars. The results obtained were Summarized as follows; 1.At the mixing ratio of 1:1, the highest bulk densities were showed by foaming mortars, respectively. But, it gradually was decreased in poorer mixing ratio and more addition of foaming agent. The decreasing rates of bulk densities were increased in richer mixing ratio and more addition of foaming agent. 2.The bulk densities were decreased up to 38.8-55.9% by mix-foaming type and 9.7-23.6% by pre-foamed type than cement mortar. 3.At the mixing ratio of 1:1, the lowest absorption rates were showed by foaming mortars, respectively. But, it gradually was increased in poorer mixing ratio and more addition of foaming agent. The increasing rates of absorption rates were increased in richer mixing ratio and more addition of foaming agent. 4.Absorption rates when immersed in 72hours were showed up tp 3.41-5.85 times by mix-foaming type and 1.05- 1.S5times by pre -foamed type than cement mortar, it was significantly higher at the early stage of immersed time than cement mortar. 5.The correlations between bulk density and absorption rate were highly singnificant, respectively. The multiple regression equations of bulk density and absorption rate were computed depending on a fuction of mixing ratio and addition of foaming agent. it was highly significant respectively.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.18-24
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• 1999

Microcellular foaming is being researched as a method of maintaining and improving the mechanical characteristics of plastics as well as saving the material costs. This can not only improve the mechanical properties including impact strength of plastic by producing cells with the size of few ${\mu}$m diameters within the plastic, but also can save the material cost of plastic products with the general volumetric expansion of 2 to 10 times. But quite a long time is required for the gas to be absorbed in the plastic. Therefore consistent research should be done to reduce the saturation time of gas into the plastic and this paper provides the method of water microcellular foaming process as one of the methods using the high diffusivity of water. In addition, we can improve impact property of foamed plastic by using this method.

• Polymer(Korea)
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• v.24 no.4
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• pp.529-537
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• 2000

The effects of the gel content on the cell structures of PP sheets by using an electron-curing system were investigated. Three extruded PP sheets crosslinked by three different doses were used for the batch foaming process with the supercritical state $CO_2$. Experiments were also performed in order to study the effects of the gel content, saturation pressure and temperature on cell structures. Then foaming conditions, such as temperature and duration of time, were changed. The amount of gas absorbed into PP samples was not affected by gel contents and the operating condition of saturation pressure, which was higher than 2000 psi. The foam cells of PP with a low gel content grew irregularly at a higher foaming temperature and for a longer duration of foaming time. However, PP samples with high gel content showed even cell structures and narrow tell size distributions under the severe conditions of high foaming temperatures and long duration of foaming time.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.341-345
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• 2001

New technoloty called microcellular foaming process was developed at MIT in 1980's. Although it has many good things, it could not be used it all sides of manufacturing plastics. Because it takes a long time for making foamed goods. So microcellular foaming injection molding process appeared to solve this problem. The first purpose of this research is to measure the impact strength as foaming magnitude of microcellular foamed plastics. There are two methods such as batch process and microcellular foaming injection molding process in making foamed plastics. According to the experimental data, the impact strength of each specimen was measured to find out the influence of foaming magnitude of microcellular foamed plastics.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.168-174
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• 2005

Nowadays, the companies use polymer materials for many purposes fur they have many advantages. The costs of these materials take up too high a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2,\;N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. In previous research, many facts of microcellular foaming process are founded its characteristics. But previous researcher found the characteristics of microcellular foaming process with pure gas, for example $CO_2,\;N_2$ and so on, they did not found the characteristics of microcellular foaming process with one more gases. If one more gases inlet the resin, the characteristics of microcellular foaming process is changed very amazingly. In this paper, discuss on the characteristics of microcellular foaming process wi th gas cocktail about cell morphology.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.351-352
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• 2007