Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of varying molar ratios of aromatic imide-amines
and 4,4′-diaminodiphenylsulfone (DDS) were investigated by the dynamic differential scanning calorimetry. The imide-amines
were prepared by reacting 1 mole of benzophenone 3,3′,4,4′-tetracarboxylic acid dianhydride (B) with 2.5 moles of 4,4′-diaminodiphenyl
ether (E)/ or 4,4′-diaminodiphenyl methane (M)/ or 4,4′-diaminodiphenylsulfone (S) and designated as BE/ or BM/ or BS. The
mixture of imide-amines and DDS at ratio of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 were used to investigate the curing
behaviour of DGEBA.
The multiple heating rate method (5, 10, 15 and 20°C min−1) was used to study the curing kinetics of epoxy resins. The peak exotherm temperature was found to be dependent on the heating
rate, structure of imide-amines as well as on the ratio of imide-amine: DDS used. A broad exotherm was observed in the temperature
range of 180–230°C on curing with mixture of imide-amines and DDS. Curing of DGEBA with mixture of imide-amines and/or DDS
resulted in a decrease in characteristic curing temperatures. Activation energy of curing reaction as determined in accordance
to the Ozawa’s method was found to be dependent on the structure of amine. The thermal stability of the isothermally cured
resins was also evaluated using dynamic thermogravimetry in a nitrogen atmosphere. The char yield was highest in case of resins
cured using mixture of DDS: BS (0.25:0.75; EBS-3), DDS: BM (0.5: 0.5; EBM-2) and DDS: BE (0.5: 0.5; EBE-2).
Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of maleic anhydride (MA)/or nadic anhydride (NA)
or mixture of MA/NA: 4,4′-diaminodiphenyl sulfone (DDS) in varying molar ratios were investigated using differential scanning
calorimetry. Curing behaviour of DGEBA in the presence of varying amounts of DDS:MA/NA was evaluated by recording DSC scans
at heating rates of 5, 10, 15 and 20°C min−1. The peak exotherm temperature depends on the heating rate, structure of the anhydride as well as on the ratio of anhydride:
DDS. Thermal stability of the isothermally cured resins was evaluated by thermogravimetry. The char yield was highest in case
of resins cured using mixture of DDS:MA (0.75:0.25; sample EM-1) and DDS:NA (0.75:0.25, sample EN-1).
Authors:Arunjunai Raj Mahendran, Günter Wuzella, Andreas Kandelbauer and Nicolai Aust
the curekinetics of such systems is becoming increasingly important, especially when it leads to reliable predictions of the end-use properties of the cured network.
Kinetics of epoxy curing with anhydride hardener was studied by numerous
Authors:Blaž Likozar, Romana Cerc Korošec, Ida Poljanšek, Primož Ogorelec and Peter Bukovec
–urea–formaldehyde (MUF) resins
Curingkinetics of MUF resins has not been studied extensively up to date. Higuchi et al. [ 2 ] proposed a model in which the melamine residues, incorporating a small amount of urea residues, form a three
In this work the curing kinetics behaviour of a rubber modified epoxy amine system is investigated through calorimetric analysis.
This study is part of a wider investigation on new epoxy formulations to be used as matrices of composite materials. The aim
is to enhance both the processing behaviour and the mechanical properties of the matrix in order to obtain higher performance
composites for more demanding applications. The epoxy system is blended with a high molecular mass rubber containing functional
groups reactive towards the epoxies. The formation of a rubber/epoxy network can be achieved by means of a 'pre-reaction'
between the epoxy monomers and the rubber functional groups, carried out in the presence of a suitable catalyst and before
the resin is cured with the amino hardener. In this work the influence of both the rubber and the catalyst on the resin cure
kinetics is analysed.
Authors:B. Erdoğan, A. Seyhan, Y. Ocak, M. Tanoğlu, D. Balköse and S. Ülkü
The cure kinetics of epoxy resin and epoxy resin containing 10 mass% of natural zeolite were investigated using differential
scanning calorimetry (DSC). The conformity of the cure kinetic data of epoxy and epoxy-zeolite system was checked with the
auto-catalytic cure rate model. The results indicated that the hydroxyl group on the zeolite surface played a significant
role in the autocatalytic reaction mechanism. This group was able to form a new transition state between anhydride hardener
and epoxide group. The natural zeolite particles acted as catalyst for the epoxy system by promoting its curing rate.
Authors:Marta Sánchez-Cabezudo, Margarita Prolongo, Catalina Salom and Rosa Masegosa
The cure kinetics
and morphology of diglycidyl ether of bisphenol A (DGEBA) modified with polyvinyl
acetate (PVAc) using diaminodiphenylmethane (DDM) as hardener were investigated
through differential scanning calorimetry (DSC) and environmental scanning
electron microscopy (ESEM). Isothermal curing measurements were carried out
at 150, 120 and 80C. The kinetic parameters were obtained using the general
autocatalytic chemically controlled model. The comparison of the kinetic data
indicates that the presence of PVAc does not change the autocatalytic nature
of the cure reaction. Two Tg’s
were observed in the fully cured samples of the modified systems. ESEM micrographies
confirm the biphasic morphology.
Authors:M. Alonso, M. Oliet, J. García, F. Rodríguez and J. Echeverría
Kinetics of thermosetting polymers curing is difficult to study by isothermal
methods based on the differential scanning calorimetry (DSC) technique. The
difficulty is due to the low sensitivity of the equipment for total reaction
heat measurements during high temperature process. The aim of this paper is
to display the equivalence between a dynamic model, the Ozawa method, and
an isothermal isoconversional fit, which allows predicting the isothermal
behavior of the resol resins cure through dynamic runs by DSC. In this work,
lignin–phenol–formaldehyde and commercial phenol–formaldehyde
resol resins were employed. In addition, the isothermal kinetic parameters
for both resins were performed by means of transformation of the data obtained
from the dynamic Ozawa method.