Abstract

This chapter covers two major classes of polymer foams, the conventional foams formed by foaming agents and syntactic foams. The first part presents the basics of polymer foaming through the use of blowing agents including a brief introduction on blowing agents and the common foaming methods used by both laboratories and industries. Current technologies used for specialty foam fabrication are included in the discussion. The multiple roles played by nanoparticles during foam formation and the effects on the foam properties are addressed in detail for nanocomposite foams. The various factors affecting the formation ofmicrocellular foams and the properties of microcellular foams are then discussed. Two detailed examples for high-performance polymer foams are highlighted in the article. An exceptional section is devoted to syntactic foams, covering both the processing and the mechanical behaviors. It starts with general preparation of syntactic foam in a laboratory-based environment. The discussion highlights the typical mechanical behavior as well as the change in mechanical behavior observed when the content of microspheres is changed. Details on how the content of microspheres affects the mechanical and fracture properties of syntactic foams are presented. Besides looking at various content of microspheres, the existence of various toughening mechanisms in syntactic foams and the kind of toughening strategies can be used to improve the toughness of syntactic foams are also included in the section. Finally, some of the issues concerning polymeric foams and the latest developments in the field including future trends are addressed.