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: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.
Resin injection repair is a common method to repair delamination damage in polymer matrix composites (PMCs). To repair high-temperature
PMCs, the resin should have a very low viscosity, yet cure into a compatible adhesive with high temperature stability. Normally,
thermosetting polymers with high glass transition temperatures (Tg) are made from monomers with high room temperature viscosities. Among the high temperature resins, bisphenol E cyanate ester
(BECy, 1,1’-bis(4-cyanatophenyl)ethane), is unique because it has an extremely low viscosity of 0.09–0.12 Pa s at room temperature
yet polymerizes as a cross-linked thermoset with a high Tg of 274°C. BECy monomer is cured via a trimerization reaction, without volatile products, to form the high Tg amorphous network.
In this study, the cure kinetics of BECy is investigated by differential scanning calorimetry (DSC). Both dynamic and isothermal
experiments were carried out to obtain the kinetic parameters. An autocatalytic model was successfully used to model isothermal
curing. The activation energy from the autocatalytic model is 60.3 kJ mol−1 and the total reaction order is about 2.4. The empirical DiBenedetto equation was used to evaluate the relationship between
Tg and conversion. The activation energy of BECy from the dynamic experiments is 66.7 kJ mol−1 based on Kissinger’s method, while isoconversional analysis shows the activation energy changes as the reaction progresses.
Authors:J. Macan, I. Brnardić, M. Ivanković, and H. J. Mencer
Summary A kinetic study of cure kinetics of epoxy resin based on a diglycidyl ether of bisphenol A (DGEBA), with poly(oxypropylene) diamine (Jeffamine D230) as a curing agent, was performed by means of differential scanning calorimetry (DSC). Isothermal and dynamic DSC characterizations of stoichiometric and sub-stoichiometric mixtures were performed. The kinetics of cure was described successfully by empirical models in wide temperature range. System with sub-stoichiometric content of amine showed evidence of two separate reactions, second of which was presumed to be etherification reaction. Catalytic influence of hydroxyl groups formed by epoxy-amine addition was determined.
Authors:L. Barral, J. Cano, J. López, I. López-Bueno, P. Nogueira, C. Ramírez, A. Torres, and M. Abad
Cure kinetics using a differential scanning calorimetry (DSC) technique were analyzed for a thermoplastic modified tetraglycidyl-4,4′-diaminodiphenylmethane
(TGDDM) epoxy resin cured with diaminodiphenylsulphone (DDS), an aromatic diamine. The neat resin and its blends with the
poly(styrene-co-acrylonitrile) (SAN) of various compositions were studied by applying a phenomenological model proposed by
Kamal. Kinetic parameters were determined by fitting experimental data. This model gives a good description of cure kinetics
up to the onset of vitrification. Diffusion control was incorporated to describe the cure in the latter stages of cure. The
results showed that the addition of SAN did not alter the nature of the reaction, but the reaction rates and final conversions
decreased when SAN contents increase, due to reduction of mobility of the reacting species.
Authors:L. Barral, J. Cano, J. López, P. Nogueira, M. Abad, and C. Ramírez
Differential scanning calorimetry (DSC) was applied to study the cure kinetics of an epoxy system containing both tetraglycidyl
4,4′-diaminodiphenylmethane (TGDDM) and a multifunctional Novolac glycidyl ether resin, cured with 4,4′-diaminodiphenylsulfone
(DDS). The experimental data were analyzed in terms of a mechanistic model proposed by Cole, which includes the etherification
reaction. The kinetics can be completely described in terms of three rate constants, which obey the Arrhenius relationship.
This model gives a good description of the cure kinetics up to the onset of vitrification. The effect of diffusion control
was incorporated to describe the cure in the later stages. By combining the model and a diffusion factor, it was possible
to predict the cure kinetics over the whole range of conversion, including an analysis of the evolution of different chemical
species during the curing process. Good agreement with the experimental DSC data was achieved with this mechanistic model
over the whole range of cure when the etherification reaction was assumed to be of first order with respect to the concentrations
of epoxide groups, hydroxy groups, and the tertiary amine groups formed in the epoxide amine reaction.
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