A continuous extrusion process for the manufacture of microcellular and open-celled polyolefin foams is presented. The major plastics used in this study were low density polyethylene (LDPE) and Polystyrene (PS). To date, studies on microcellular foaming have centered around closed-cell structures. When an open-celled microcellular foam is developed, it will have a large number of industrial applications. The purpose of this research is to form the scientific and engineering basis needed to produce open-celled microcellular foams.

This thesis presents the effective strategies for increasing the open-cell content and the cell density of LDPE or LDPE/PS polymers blend foams. The effects of processing and materials parameters on the foam morphologies were thoroughly studied using a single-screw foam extrusion system. By tailoring the processing and materials parameters, microcellular open-celled LDPE/PS blend foams with more than 95% open-cell content and 10⁹ cells/cm³ were successfully produced.