I. Alig et al., TEMPERATURE MODULATED DIFFERENTIAL SCANNING CALORIMETRY DURING ISOTHERMAL CURING OF PHASE-SEPARATING POLYMER NETWORKS, Journal of non-crystalline solids, 235, 1998, pp. 504-509
Temperature modulated differential scanning calorimetry (TMDSC) and co
nventional differential scanning calorimetry (DSC) have been applied f
or investigation of isothermal curing of two component polymer network
s separating into two phases during network formation. The network com
ponent consists of diglycidylether of bisphenol A (DGEBA) cross-linked
with diaminodiphenyl methane (DDM) and the linear polymer component i
s polyethersulfone (PES). Isothermal curing experiments at 373 K and h
eating experiments after defined isothermal curing times are combined
to investigate the evolution of the glass transition temperatures duri
ng reaction. While in the initial stages of the reaction the systems a
re homogeneous mixtures, phase separation takes place in the course of
curing into a DGEBA/DDM-rich and a PES-rich phase. Since in the conve
ntional isothermal DSC measurements the changes in the heat capacity,
when the system undergoes a transition from a liquid to a glassy solid
during network formation, are masked by the heat of reaction, TMDSC w
as applied to resolve both effects. In the heating experiments after d
efined isothermal curing periods the changes in the heat capacity due
to the glass transition were resolved for both phases by TMDSC whereas
in the conventional DSC measurements the glass transition temperature
could only be detected for the DGEBA/DDM-rich phase. The phase separa
tion process is indicated by TMDSC for curing times above 50 min for a
curing temperature of 373 K. (C) 1998 Elsevier Science B.V. All right
s reserved.