KINETIC AND RHEOLOGICAL STUDIES OF AN UNSATURATED POLYESTER CURED WITH DIFFERENT CATALYST AMOUNTS

An unsaturated polyester resin was cured with different catalyst conte nts. The crosslinking process was followed by static and dynamic visco simetry and by differential scanning calorimetry (d.s.c.). Activation energies were determined from the gel times obtained by viscosimetry a nd from the variation in the maximum exotherm temperature obtained by d.s.c. at different heating rates. The existence of a threshold in the amount of catalyst to use is shown by analysis of the gel times. The effect of catalyst content on the glass transition temperatures of the different mixtures has been analysed taking into account the crosslin k density, measured by means of the rubber modulus obtained by dynamic mechanical tests.