Combined Effects of Chemical and Microcellular Foaming on Foaming Characteristics of PLA (Poly Lactic Acid) in Injection Molding Process

摘要

Foaming technology used in the plastic production process makes it possible to reduce costs and lighten the products, which is why this technology is widely used. Foaming technology is generally categorized as involving either a “Chemical Foaming Process” or a “Physical Foaming Process,” the latter also referred to as a “Microcellular Foaming Process” (MCP). In both processes, gas particles dissolved inside a polymer create cells. For the chemical foaming process, chemical blowing agents are mixed with plastic pellets, whereas for MCPs, gas is directly supplied to a polymer melted inside the barrel of an injection molding machine. The cell morphology changes when either the chemical foaming process or the MCP is applied in an injection foaming process. This study aims to compare and analyze the change of the cell morphology in such a case. In particular, Poly Lactic Acid (PLA) is used in the experiment. In this study, the foaming characteristics of a biodegradable material (PLA) and a convectional material - Acrylonitrile Butadiene Styrene (ABS) - are compared and analyzed. The analysis of the experiment results is done based on an analysis of the foaming ratio and a comparison of the cross-section of the cell morphology of specimens under different experimental conditions. For the former, a weight comparison was made, while for the latter, a scanning electron microscope (SEM) was utilized.