HYDROLYTIC STABILITY OF UNSATURATED POLYESTER NETWORKS WITH CONTROLLED CHAIN-ENDS

Four unsaturated polyester networks with chain ends modified by isocya nate or dicyclopentadiene (DCPD) were immersed in distilled water at 1 00 degrees C or exposed in humid atmosphere at 70 degrees C and 50 deg rees C. The hydrolytic stabilities of these materials were determined by gravimetric analyses and infrared spectrometry. The results obtaine d were compared with those obtained on standard polyesters under simil ar conditions. For a given hydrolysis rate, the modification of chain ends by an isocyanate very clearly induces a decreasing rate of weight loss within the framework of degradations involving osmotic phenomena . The controlling of chain ends by DCPD does not reduce mass loss effi ciency, but it does limit the hydrolysis rate. (C) 1997 Elsevier Scien ce Limited.