Effect of using nucleating agent on structure and features of Polyethylenefoams

Polymeric foams are a group of artificial products that naturally or synthetically have two phases:gas and polymer. These light materials have other special properties in addition to low density whichmake them more important. The expansion process comprises three major steps: nucleation, bubblegrowth, and stabilization. Nucleation or formation of expandable bubbles begins within the polymermelt that has been super saturated with the blowing agent. Typical nucleating agents are solidmaterials which are dispersed through polymer melt and remain solid within expansion stage.In this work coated calcium carbonate with calcium stearate was used to produce nucleation sites incross-linked low density polyethylene as a polymeric base for foaming. Calcium carbonate isprimarily used in polyethylene to reduce cost. Result shows using this mineral material in addition toreducing product cost, enhance some properties of cellular products.From scanning electron microscopy photos of different compounds and cellular products, it could bedemonstrate that decomposition of blowing agent in finely dispersed composite of PE with up to ۱۱wt% of coated calcium carbonate, cause increased bubble number in unit of volume of foams andmake more uniform cell morphology. Bubble rupture and void formation could be observed by usinggreater amount of this powder; which have no desirable effects on physical and mechanicalproperties. In addition results for density and mechanical characteristics such as tensile andcompression behavior of specimens were tested and effect of both presence of different amount ofmentioned filler and mixing conditions were delicately investigated