This thesis presents an innovative structural foam injection molding technology for production of HDPE fine-celled. Structural foam products are widely used because of lightweight and superior strength-to-weight performance. However, structural foam products suffer some drawbacks. The purpose of this research is to develop a new technology to overcome these limitations.

The basic strategies for producing a fine-celled foam with uniform cell structure are:​ (a) to maintain homogeneous single-phase solution;​ (b) to adopt an effective nucleating agent, and (c) to maintain a certain pressure-drop rate. The strategy used in this study to improve surface quality is to use a very small amount of blowing agent to prevent premature foaming during filling. The effects of processing and material parameters on foam morphologies have been thoroughly studied. Finally, uniform fine-celled HDPE foams with a cell density of 10⁷ cells/cm³ have been successfully achieved.