EFFECTS OF CURE TREATMENT ON GLASS-TRANSITION TEMPERATURES FOR A BADGE-DDM EPOXY-RESIN

The extent of cure for epoxy resin (BADGE) with a small excess of amin e hardener (DDM, 4 w/o) was determined by assay of the epoxy groups us ing near infrared spectroscopy. The effect of cure time at 100 degrees C and postcure time at 180 degrees C has been investigated. For the l ower temperature cures the room temperature density, rho(rt), increase d with time, reaching a maximum at X(e) = 0.87, and then decreased wit h extended cure times. For postcure, there was a monotonic decrease in rho(rt) that was unrelated to the extent of cure. There was an approx imate linear relationship between glass transition temperature and ln( t), which increased even when essentially all of the epoxy groups had reacted, that is X(e) similar to 0.99. (C) 1996 John Wiley & Sons, Inc .