Investigation on the Effect of Chemical Foaming agent and Wood Flour content on Mechanical Properties, Density and Cell morphology of HDPE/EVA/ Wood Flour Hybrid Foamed Composites

In this research، the effects of chemical foaming agent and wood flour content on cell morphology، density and mechanical properties of HDPE/EVA/ Wood Flour hybrid foamed composites were investigated. For this aim، composites were prepared via melt mixing in an internal mixer، then foamed using single-stage batch foaming method. Then mechanical properties such as flexural strength، flexural and tensile modulus and density were measured. Morphology of the samples was also evaluated by scanning electron microscopy (SEM). The results of this study have indicated that the flexural strength، flexural and tensile modulus and density increases with the increase of wood flour content. However، with addition of chemical foaming agent content and EVA content، mechanical properties and density of foamed composites decreased. Moreover، wood fiber acted as nucleating agents that substantially reduced cell size and increased cell density. In addition، EVA plays an important role in foaming process by increasing the melt viscosity of the polymer matrix، in a way that samples with higher content of EVA have the highest cell density and the lowest cell size.