RHEOLOGICAL STUDY OF CROSS-LINKING AND GELATION IN CHLOROBUTYL ELASTOMER SYSTEMS

The multiple waveform rheological technique was used to study the cros slinking behaviour of a filled elastomeric system at various temperatu res. The gel point could be precisely determined from a single experim ent at each temperature using this technique. At the instant of gelati on, the storage (G') and loss (G'') moduli scale with frequency in an identical manner, i.e. similar to omega(n). The relaxation exponent, n was found to be approximately constant (0.14) in the temperature rang e studied. Reported values of n for chemically crosslinking systems ar e typically higher; the low value in this case can be attributed to th e high molecular weight of the prepolymer and the presence of iiller. The gel times at various temperatures were used to calculate an appare nt activation energy of the curing reaction, which was found to be app roximately 92 kJ mol(-1). Copyright (C) 1996 Elsevier Science Ltd.