Density Graded Polyethylene Foams Produced by Compression Moulding Using a Chemical Blowing Agent

Density graded polyethylene foams were produced using a chemical blowing agent and compression moulding. To control the local density inside the foams, the top and bottom plates of a compression moulding set-up were placed at different temperatures and moulding times in order to produce symmetric and asymmetric structural foams. Due to different temperature gradients produced inside the samples, complex density profiles were created. From the samples obtained, a complete morphological analysis was performed to extract cell size and cell density across foam thickness in relation with density profiles. Also, to determine the effect of density profile on the mechanical properties, tensile and flexural characterizations were performed. The results obtained are discussed in relation with optimum properties vs. bulk foam density.