Differences in the glass transition temperatures (T-g) of epoxy resins were
observed when their samples for differential scanning calorimetry (DSC) me
asurements were prepared by two different methods. The differences tin T-g)
are believed to be due to the effects of interfacial residual stress, whic
h is present only in the samples of lower T-g prepared with the formation o
f a "chemical" contact between epoxy resin and aluminum (pan) which have mi
smatched thermal expansion coefficients. Both types of the samples also sho
wed, respectively, lower T-g when they were prepared by a fast-cooling proc
ess than when they were prepared by a slow-cooling process. This suggests t
hat matrix residual stress, which is present in both types of the samples,
as well as interfacial residual stress, has similar effects on the T-g of e
poxy resins. This conclusion is substantiated by the results of the change
of contact pattern and the freezing stress experiments.