Summary Polymers have a great interest for the study and design of new materials. Among these materials are epoxy resins, that have good properties, such as low shrinkage during cure, good adhesion, high water and chemical resistance, etc. They have also fast and easy cure in a broad range of temperatures. TTT diagrams are very helpful to design new epoxy materials as they allow the search for very important final properties, such as thermal stability, conversion or glass transition temperature of a material cured through a selected curing cycle. In this work the dependence of the thermal stability on the selected curing cycle for a DGEBA/1,2 DCH system was studied.
The curing of a thermoreactive alkyd-melamine-formaldehyde resin system was investigated by rheologycal, TG and TMA-analysis,
in order to construct the time-temperature-transformation diagram. The points of the gelation curve were determined by measuring
the increase in viscosity during isothermal curing at different temperatures. A power-function could be fitted to the gelation
curve, which is suitable to estimate gelation at any curing conditions, as well as to establish storage conditions. The reaction
in the resin matrix was followed by monitoring the loss of mass during isothermal curing at different temperatures. The final
section of the resulted iso-curing temperature (iso-Tcure) diagrams could be fitted with logarithmic functions, which may be used for estimating the conditions needed to a given,
desirable mass loss, i.e. conversion. The steepness of the curves increases with temperature suggesting the forthcoming of
degradation during cure with increasing temperature. From these data the iso-mass loss curves of the TTT-diagram were constructed.
For determining the iso-Tg curves of the TTT-diagram isothermal curing was carried out in a drying oven at different temperatures,
followed by TMA measurements. The iso-Tcure diagrams served to determine Tg, and to construct the iso-Tg curves of the TTT diagram. Vitrification curve is far beyond conditions of storage, curing and degradation, meaning that
the resin matrix is in rubbery physical state before, during and after the cure. Curing conditions resulting degradation can
also be estimated from the TTT-diagram.
Authors:L. Barral, J. Cano, J. López, I. López-Bueno, P. Nogueira, C. Ramírez, A. Torres, and M. Abad
The effect of thermal degradation on the mechanical behaviour of a system containing both tetraglycidyl-4-4′-diaminodiphenylmethane
(TGDDM) and a multifunctional novolac glycidyl ether (EPN) resins, cured with 4,4′-diaminodiphenylsulphone (DDS) has been
studied using dynamic mechanical analysis (DMA) and tensile tests. Different curing paths using the isothermal time-temperature-transformation
(TTT) diagram for this system were designed, obtaining thermosetting materials with different conversions. The influences
of the degree of cure and of the aging temperature were also studied. The results showed different trends in the dynamic mechanical
properties and an increase in the stiffness of the material with increasing aging time. Changes were faster and more intense
with the higher temperature.
Authors:V Vargha, O Vorster, Zs Finta, and G Csuka
The gelation of a powder coating and its matrix based
on a saturated carboxyl functional polyester resin and triglycidyl isocyanurate
of different diastereomer racemate composition was investigated by rotational
viscometry. The iso-Tcure
diagrams have been determined directly by isothermal viscometric measurements
and the gelation curves for the TTT-diagram
have been constructed. To the measured section of the gelation curves power
functions could be fitted and with their help the reactivity of the investigated
systems were compared. The ratio of the two diastereomer racemates of TGIC
has a significant effect on the reactivity of the coating, as it was also
supported by DSC measurements. β-TGIC is of highest reactivity, and by
increasing its ratio in TGIC, reactivity increases, and adversely effects
the performance of the powder coating. Commercial TGIC-s have similar reactivity,
comparable to that of high α-TGIC. The reactivity of the matrix is higher
than that of the powder.
Authors:A. Cadenato, J. Salla, X. Ramis, J. Morancho, L. Marroyo, and J. Martin
In the present work, gelation and vitrification experimental data are obtained by TMA and DMTA techniques using the same thermoset
based on an epoxy-amine system. The results show that the times obtained are not equivalent and depend on the technique used.
An attempt has been made to compare both determinations using the degree of cure obtained by means of DSC technique. The principal
conclusion that we want to emphasize is that it is the conversion degree and not the time of the phenomenological changes
that take place during cure, that is the link to connect and interrelate the results obtained with different techniques. A
method is also described for constructing the TTT diagram with only DSC and TMA or DMTA data.
Authors:S. M. Sabzevari, S. Alavi-Soltani, and B. Minaie
state. Vitrification is the point at which the resin changes from the rubbery state to the solid glassy state. The TTTdiagram may be augmented by adding iso-conversion, iso-glass transition temperature (iso- T g ), and iso-viscous contours as well as
Authors:Zoltán Budai, Zsolt Sulyok, and Viktória Vargha
authors dealt with the analysis of curing of unsaturated polyester resins [ 8 , 9 ]. The behaviour of thermosetting systems before, during and after processing is well demonstrated by their Time-Temperature-Transformation (TTT) diagram, which represents
Authors:Vera Alejandra Alvarez and Claudio Javier Pérez
degree). Then, this effect decreased with the continuous addition of CaCO 3 .
CTT and TTTdiagrams for: a PP-matrix and composites: PP–5 mass% SiO 2 , PP–5 mass% Al 2 O 3 , PP–5 mass% CaCO 3 and PP