The extent of reactions occurring during reactive blending of thermopl
astic polyurethanes (PUR) with functionalized polyolefins or reactive
compatibilizers has been studied using ethylene!acrylic acid and styre
ne/maleic anhydride copolymers. Due to interfacial segregation effects
, no reaction was found with carboxylic groups and only little with an
hydrides. Here 1-2% reaction products are generated after 30 min with
preferentially multiple additions at the same molecules. Therefore, wi
th incompatible polymers, reactive coupling is negligible with PUR und
er realistic blending conditions.