The mechanical properties of ESI/LDPE foam blends and sport applications

Mechanical tests were performed on foamed blends of Ethylene - Styrene Interpolymer (ESI) with low density polyethylene (LDPE). In compressive impact tests the foams, of density around 50 kg m(-3), have higher initial yield stresses than Ethylene Vinyl Acetate (EVA) foam of the same density. Impact, Instron and creep tests were analysed to estimate the effective air pressure in the undeformed foam cells, and the initial yield stress. The rate dependence of the latter increases slightly with increasing ESI content. The ESI/LDPE foams have improved impact properties, compared with EVA foams of similar density, for leg protection applications. Analysis of creep tests shows that air diffuses from the cells at a similar rate to EVA foams of a greater density. The ESI/LDPE foams have potential to replace higher density EVA foams in running shoes.