Viscoelastic properties of polyethylene syntactic foam with polymer microballoons

Syntactic foam products are most often made from glass microballoons embedd ed in a thermosetting polymer matrix, and they have good mechanical and the rmal properties. However, the glass microballoons easily break in shear and are therefore very difficult to use for manufacturing methods that cause s hearing of the material. Polymer microballoons are an alternative by which it is possible to produce a foamed product using unmodified commercial extr uders or injection moulding machines. The present study deals with the visc oelastic properties of extruded polyethylene (PE) and a foam made from PE a nd approximately 40 volume percent of polymer microballoons. Results are sh own from creep tests carried out at three temperatures and with three force levels, and from stress relaxation tests carried out at room temperature a nd with five deformation levels. The overall conclusion was that for some a pplications the foam will be the best choice, whereas for others it is more advantageous to use bulk polyethylene.