Density Graded Linear Medium Density Polyethylene Foams Produced under a Temperature Gradient with Expancel Microbeads

In this work, density graded foams were produced using linear medium density polyethylene as the matrix and different grades of Expancel microbeads. Local density inside the foams was controlled by setting independently the top and bottom plates of a compression mould at different temperatures and by controlling moulding time. Due to the temperature gradient, complex density profiles were produced and a complete morphological analysis was performed to extract average cell diameter and cell density across foam thickness. Finally, the tensile and flexural moduli are reported and discussed in relation with foam structure.