A series of polyurethane-ureas has been synthesized by solution polyaddition reaction of the following components: a polyester-diol (PEA), or a polyetherdiol (PTMG) and a diisocyanate, such as 4,4'-dibenzyl diisocyanate (DBDI) or 4,4'-methylene-bis(phenyl-isocyanate) (MDI). For the chain extention step some aromatic diamines like: 2,5-bis-(4-amino-phenylene)-1,3,4-oxadiazole (DAPO), 4,4'-methylene dianiline (MDA) and 4,4'- diamino-dibenzyl (DAB)