• 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.25 no.9
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• pp.71-77
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• 2008

Microcellular foaming plastics create a sensation at polymer industrial for lowering product costs and overcoming a lowering of mechanical intensity. Among many advantages, microcellular foaming plastics is well known to have a good acoustical properties. This research based on the experiment of sound absorption and transmission characteristics inquire into acoustical properties of microcellular foaming plastics. Difference of transmission loss of microcellular foaming plastics and solid materials was defined as cell effect. Also, cell effect is expressed by sound reflection and sound absorption. This study is expected to fundamental research to present economical, functional alternative plan for products using sound absorption and transmission materials.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.419-420
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• 2007

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1828-1833
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• 2003

In a foaming process of microcellular plastics (MCPs) with a batch process, amorphous plastics and crystalline plastics have different characteristics for a foaming temperature. It is known that a foaming of amorphous plastics occurs at the temperature above a glass transition temperature, however, it is discovered that crystalline plastics do not take place above a glass transition temperature without exception, and even though the foaming occurs, it does not in all the range. In this research, to measure foaming temperature of crystalline polymer, a foaming experiment was performed using one of the typical crystalline polymer, polypropylene. To analyze whether the foaming occurs both at amorphous and crystalline fields, SEM was applied

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.196-201
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• 2000

There is a great demand for reducing the amount of material used in mass-produced plastics parts for material cost constitutes a large percentage of the total cost of a product up to 75% It may be noted that the price of plastics is directly related to the price of petroleum. Material reduction therefore decreases the amount of oil needed for the manufacture of plastics and thus help conserve this natural resource. Therefore microcellular foaming process(MCPs) was studied for solving this problems alternatively in 1980's at M. I. T. Until now in microcellular plastics processes carbon dioxide gas was mainly used for microcellular foaming Because carbon dioxide has more solubility than any other gases such as nitrogen gas or helium gas. The purpose of the this research is measurement of changing of the microcellular plastics' weight by using nitrogen gas in injection molding an comparing weight reduction of microcellular foamed plastics for using carbon dioxide gas with nitrogen gas.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.335-340
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• 2001

We use so many plastic products in everyday. Because polymer materials have a lot of merits including low cost and easiness of forming, they are widely used in many manufacturing industries. Microcellular foaming process was developed at MIT in 1980's to save a quantity of materials and increase mechanical properties. The improvement of strength is very important factor in relation with the reduction of mass. So the first purpose of this research is to improve the strength of the microcellular foamed plastics as variation of glass-fiber's volume friction. Also the characteristic of filler such as glass-fiber was presented in a microcellular foaming process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.585-590
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• 1997

Conventional foaming process has defects such as lower mechanical properties than ur~foaming material due to non-uniform cell distribution and environmental pollution problem caused by chemical blowing agency. So, a new foaming process such as Microcelluar plastics has been introduced to use inactive gases as a foaming agency. In order to apply Microcellular plastics for mass production process system such as extrusion, injection molding and blow molding, it needs to predict the change in material properties of polymer according to the amount of meltingas. In Polymer molding applying Microcelluar plastics, the change of viscosity among several material properties is the most important factor. Therefore, this paper is aimed to establish the method which not only finds out but also predicts the change of viscosity of ABS(Acrylonitri1e Butadiene Styrene) resin according to inert gas amount in extrusion molding.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.621-626
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• 2001

Microcellular foaming process was developed at MIT in 1980's to save a quantity of raw materials and improve mechanical properties. There are many process variables in appling microcellular foaming process to the conventional injection molding process. Of all process variables, part dimension control and shrinkage are the most influential on the post molded dimension. The post molding dimensional change of thermoplastic resins is important to tool designers for predicting the specific difference of molded part vs. actual mold cavity. Generally, articles injection molded are smaller in size than the cavity; hence, the term shrinkage factor is used to define the allowance a designer specifies. It is important to consider the factors that influence molded part dimension. According to ASTM Designation: D 955, shrinkage from mold dimensions of molded plastics was measured. In injection molding, the difference between the dimensions of the mold and of the molded article produced therein from a given material may vary according to the design and operation of the mold. In this paper, shrinkage data of molded plastic parts was obtained. It can be an important information for designing optimum mold system in a microcellular foaming injection molding process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.403-404
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• 2009

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.816-822
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• 2001

The thermoforming process is widely used in the plastics industry to produce articles for the packaging, automotive, domestic construction and leisure industries. The microcellular foaming process appeared at M.I.T. in 1980s to save a quantity of polymer materials and increase their mechanical properties. The glass transition temperature of polymer materials is one of many important process variables in appling the microcellular foaming process to the conventional thermoforming process. The goal of this research is to evaluate the relation between gas absorption and glass transition temperature in batch process using microcellular foaming process. The weight gain ratio of polymer materials has a conception of gas absorption. Polymers such as acrylonitrile-butadiene-styrene(ABS), polystyrene(PS) have been used in this experiment. According to conventional Chows model and Cha-Yoon model, it was estimated with real experimental result to predict a change of glass transition temperature as a function of the weight gain ratio of polymer materials in batch process to gain microcellular foamed plastic products.