TGDDM/DICY epoxy cure kinetics and properties
FTIR and non-isothermal DSC show TGDDM/dicyandiamide cures in two autocatalytic stages, then a stiff, low-water-uptake network.
Source
Reaction mechanism, cure behavior and properties of a multifunctional epoxy resin, TGDDM, with latent curing agent dicyandiamide
Study at a glance
- Design
- Other — FTIR/DSC kinetic analysis of TGDDM/DICY epoxy cure and cured-material properties
- N
- Polymer cure kinetics and materials testing — no sample N
- Population
- TGDDM/DICY epoxy formulations
- Outcome
- Cure activation energies and high-temperature adhesive/dielectric properties
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Inspect source passages
TGDDM/DICY epoxy cure kinetics and properties
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Kissinger activation energies are 69.7 and 88.7 kJ mol–1
The typical Kissinger plots of the two cure processes were drawn in and the calculated activation energy values were 69.7 and 88.7 kJ mol −1 , respectively.
Total curing enthalpy is 797–867 J g–1 independent of heating rate
The total curing reaction enthalpy, which ranged from 797 to 867 J g −1 within the experimental errors limit (5% of the average value), was independent of the heating rate.
What they did
They mixed stoichiometric TGDDM with micronized DICY, followed staged oven cures while recording FTIR, then ran DSC at 5–20 °C min–1. Kissinger, FWO, and Starink analyses mapped Ea(α). Cured plaques were tested for tensile/shear strength, dielectric constant, and water uptake versus DGEBA/DICY.
What they found
Epoxy (906 cm–1) is consumed while DICY amines become OH; nitriles then convert to amide (1687 cm–1). Two DSC peaks split at α = 0.45; Kissinger Ea is 69.7 then 88.7 kJ mol–1. Total enthalpy is 797–867 J g–1, independent of heating rate. At α > 0.85 diffusion dominates. Cured TGDDM/DICY has 12.6 MPa shear at 200 °C, εr = 3.26 at 1 MHz, and 0.41% water uptake.
The limits
What it doesn't show
Isothermal DSC and full rheology during gelation are not reported. FTIR peak assignments use stepwise oven cures, not in situ DSC-IR. Dielectric and water data are single-condition comparisons, not a full hygrothermal aging study.
Key terms
- TGDDM
- N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenylmethane, a tetrafunctional epoxy.
- DICY
- Dicyandiamide, a latent solid amine/nitrile curing agent with long pot life.
- Autocatalytic cure
- Rate that speeds as OH products catalyze further epoxy–amine reaction.
- Isoconversional analysis
- Model-free Ea versus conversion (FWO, Starink) from several heating rates.
- Diffusion control
- Late-cure slowdown when the glassy network limits reactant mobility (α > 0.85).
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Quiz yourself
The second chemical stage of TGDDM/DICY cure is mainly
Common questions
What are the two chemical stages?
First epoxy + DICY N–H ring opening; then nitrile + generated OH → amide.
Where does the DSC split?
Around α = 0.45, matching two exotherms (185–220 and 277–313 °C).
Kissinger activation energies?
69.7 kJ mol–1 (amine–epoxy) then 88.7 kJ mol–1 (nitrile/OH stage).
Why use DICY?
Latent solid hardener: mixable, then long storage versus fast liquid amines.
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