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Micro-cellular foaming technology draws attention due to the enhancement of mechanical strength, which has been considered as a weak point of current plastic foaming technology. Foam materials produced by this technology offer improved consistency and homogeneity of cell structure, which can result in products with superior properties and uniformity(1). Thus it is widely used for commercial purposes and its market is now growing significantly. However, since the foamed injection parts have swirl marks on its surface, this technology has limited uses such as interior products, in spite of its diverse merits. In this paper, we propose surface treatment of the mold as a way to remove the swirl mark. We injected simple shape specimens with PP and PC/ABS materials and measured the surface quality values such as roughness and gloss. Also we researched the foaming characteristics of both treated and untreated surface using SEM analysis.

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The purpose of this research is to study the pressure drop profiles of biodegradable polybutylene succinate (PBS)/CO2 solutions in a slit die and to measure the rheological properties of the solutions as a function of the blowing agent concentration. A slit die with four pressure transducers has been designed to describe the effects of shear rate, temperature, pressure, and gas content on the shear viscosity and extensional viscosity of the flowing PBS/CO2 solutions. The low shear rate viscosity of the pure polymer was measured using a cone and plate rheometer. Extensive experiments were conducted to investigate the polymer/gas solution viscosities at five different shear rates, three temperatures and five gas contents. Cross-Carreau model and generalized Arrhenius equation were used to describe the shear-viscosity behaviors of PBS/CO2 solutions. The extensional viscosity of solution was modeled based on Cogswell’s equation.

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