MORPHOLOGY AND PHASE-STABILITY IN MELT-MI XED BLENDS WITH THERMOPLASTIC POLYURETHANES

Using maleic anhydride grafted polyethylene as blend component in blen ds with thermoplastic polyurethanes (TPU), the particle size was reduc ed dramatically in comparison to the non-reactive case. In addition, p hase adhesion was observed and the mechanical properties were improved , These improvements are due to the chemical reaction, as well as to t he influence of the lower viscosity ratio of the reactive blend system . Ethylene copolymers with different contents of acrylic acid were add ed as compatibilizer to TPU / polypropylene blends. The ethylene copol ymers ape not miscible with the blend components and no reaction with the TPU was found. Nevertheless, the particle size of tile blends was reduced. Additionally, the morphology was stabilized against coalescen ce in quiescent melt and under processing conditions. The mechanical p roperties were improved. These results are due Po the steric suppressi on of coalescence.