Use of temperature‐modulated DSC in kinetic analysis of a catalysed epoxy–anhydride system

Abstract

The curing kinetics of a catalysed epoxy-anhydride system was studied by temperaturemodulated differential scanning calorimetry. The chemical-controlled regime was analysed by empirical kinetic equations. The diffusion-controlled regime was detected by the diffusion factor, DF(α,T ), which was calculated from the ratio of the experimental rate to the chemical reaction rate. DF(α,T ) was compared with a mobility factor, MF(α,T ), which was obtained by measuring the modulus of the complex heat capacity |C p * |. The equivalence of the two factors allowed the diffusion-controlled regime to be studied using the |C p * | signal. However, the results obtained in the epoxy-anhydride system showed a limitation to the method, and this is discussed in terms of the modulation period necessary for the variation in MF(α,T ) to occur in the same conversion interval as does DF(α,T ).

Vitrification, devitrification, and dielectric relaxations during the non‐isothermal curing of diepoxy‐cycloaliphatic diamine

“…In particular, in the DGEBA–3DCM system, the measurement of the dynamic T g , which is frequency‐dependent, obtained by the C p * signal at a modulation period of 60 s (equivalent to a measuring frequency of 16.7 mHz), gives a value for the vitrification time (in isothermal measurements) that is very close to that measured by conventional DSC 28. This property is common to other epoxy‐amine systems that follow a step reaction, but it cannot be generalized to other types of reacting systems, such as the chain reaction that occurs in epoxy‐anhydride systems 29. Similarly, TMDSC can be used to determine the region of vitrification and further devitrification, which occurs during the non isothermal crosslinking reaction at a sufficiently low heating rate 6, 10.…”

Curing and thermal behavior of DGEBA in presence of dianhydrides and aromatic diamine

“…Activation energy for system cured using mixture of anhydride and amine is lower than the samples cured using either anhydrides (EB, EN) or DDS alone (ED) (Tables I and II). This could be due to the more complex mechanism of curing DGEBA in presence of mixture as reported earlier for catalyzed epoxy‐anhydride curing system 23. Considering the complex nature of curing reaction, the activation energy is an overall value including various steps of curing reaction.…”

Reaction kinetics and curing behavior of epoxies for use in a combined selective laser beam melting process of polymers

“…The Kamal–Sourour model is needed within the TTT diagram to determine the temperature dependency for different degrees of cure. Furthermore, given the range of E a determined, the results of the Kamal–Sourour model can be verified and restricted, by setting boundary conditions regarding the activation energy in accordance with the results in this article . The results of the DiBenedetto equation will be used to determine the isovitrification line.…”