Citation:
M. Zarrelli, A. A. Skordos and I. K. Partridge, Thermo-mechanical analysis of a toughened thermosetting system, Mechanics of Composite Materials, Volume 44, Number 2, March 2008, pp181-190
Abstract:
The experimental results of viscoelastic mechanical tests, at five different
levels of conversion, are reported for a thermoset composite matrix system
toughened with an appropriate percentage of a thermoplastic polymer. The results
from static tests are used to construct the master curves at a specific degree
of cure, while the shift factors are compared with the corresponding values from
dynamic experiments in order to assess the validity of the time-temperature
superposition for each conversion. Neat resin plates were cured accurately,
according to the full kinetics model for a dynamic and isothermal temperature
regime; the conversion gradient in the plane and across the thickness of the
plates was assessed by a thermal analysis of samples taken from different
locations before extracting the samples from them. The viscoelastic behaviour of
the resin matrix showed a sensible difference in the relaxation time spectrum
upon conversion according to the provisional trend of mobility theory; a higher
conversion induced a horizontal shift of the principal relaxation time for each
level of conversion, which could be related very well to the glass transition at
the same conversion. Good results were also obtained for the ultimate modulus of
the resin at a temperature just before the onset of the co-curing phase for
partially cured samples