polymer foams are extensively used in the packaging industry and as thermal insulation, buoyancy aids and structural elements in sandwich composites,because they are low density materials with relatively high strength and stiffness per unit weight,as well as high damage tolerance(1-3).the integration of polymer chloride(pvc)and other foams into sandwich structures heavily relies on the availability of detailed studies relating their microstructure with their durability and mechanical properties(4-6).for example,mechanical testing of several cross-linked pvc foams revealed that the density,polymer material and degree of cross-linking controls the elastic response,compressive and tensile strength of such foams(7-8).experimental characterization of water uptake in polymer foams describe the short and long term diffusion processes through measurements of weight gain or changes in buoyancy,as well as the associated process of degradation of mechanical properties(9-12).mechanical performance of polymer foams exposed to high moisture or immersed in liquids is an important area of research for several reasons.first of all,polymer foams have been adopted in many lightweight structural applications under various operating environments, and is thus essential that the foams maintain a satisfactory level of performance,both mechanically and for the intended functionality(13-16).secondly,