MARIA DANIELA STELESCU, DANIEL COMEAGA, MARIA SONMEZ, DANA GURAU THE MECHANICAL PROPERTIES OF SOME POLYMER COMPOSITES BASED ON NATURAL RUBBER This paper presents the development and characterization of polymer composites based on natural rubber, crosslinked using two types of vulcanization systems, as follows: the classical method using sulfur and curing accelerators and the method using peroxide in the presence of a polyfunctional monomer - trimethylolpropanetrimethacrylate. The composites were made with 0 parts to 100 parts rubber (phr) and 40 phr filler content. The physical-mechanical characteristics of resulting composites depend on the crosslinking method and on the composition. The mechanical parameters of materials were derived by processing the transmissibility curves, derived for samples with known dimensions and density. The main vibration frequencies and the quality factor, derived in the vicinity of resonances, allow to derive the elasticity and internal damping of materials.