Cure diagrams

Aronhime, M. T., Gillham, J. K. Time-Temperature Transformation (TTT) Cure Diagram of Thermosetting Polymeric Systems. Vol. 78, pp. 81 — 112. 

Figure 2.6 Time-temperature-transformation (TTT) cure diagram. Adapted from Enns and Gillham [55]...

The Time-Temperature-Transformation (TTT) Cure Diagram of Thermosetting Polymeric Systems... 

The behavior of curing thermosetting resins can be represented with the generalized time-temperature-transformation (TTT) cure diagram developed by Enns and Gillham[7] it can be used to relate the material properties of thermosets as a function of time and the processing temperature as shown in Fig. 2.28. 

J.B. Enns and J.K. Gillman. Time-temperature-transformation (ttt) cure diagram Modeling the cure behavior of thermosets. J.Appl. Polym. Sci., 28 2567-2591, 1983. 

Figure 1. Time-temperature-transformation cure diagram by Gillham [adapted from (7)].

Much of the behavior of thermosetting materials can be clarified in terms of the TTT cure diagram through the influence of gelation, vitrification and devitrification on properties. For example, gelation retards macroscopic flow, and limits the growth of a dispersed phase (as in rubber-modified systems) vitrification retards chemical conversion and devitrification, due to thermal degradation marks, the limit in time for the material to support a substantial load. 

The purpose of this review is to summarize the baac features and utility of the TTT cure diagram, discuss the experimental procedures for obtaining a diagram, present experimentally-obtained diagrams for model systems, and describe recent models that have attempted to calculate the time to vitrification on isothermal polymerization. This review will concentrate on TTT diagrams of epoxy systems. 

The isothermal TTT cure diagram summarizes the transitions that occur on isothermal polymerization, such as gelation, vitrification and devitrification. Typically,... 

In order to construct a TTT cure diagram, a series of isothermal cures are performed at different temperatures, and the relative rigidity and logarithmic decrement are recorded vs. time. From each damped wave 1/P and A are extracted the numerical methods used have been described... 

F. 4. TTT cure diagram temperature of cure vs. time to the isoviscous event, gelation and vitrification, including TBA and gel fraction data , isoviscous (TBA) O, gelation (TBA) A, vitrification (TBA) , gelation (gel fraction). The system studied was a difunctional epoxy resin, Epon 828 (DGEBA, Shell Chemical Co.), cured with a tetrafimctional aliphatic amine, PACM-20. (bis(p-aminocyclohexyl)methane, DuPont]... 

Fig. 13 is a TTT cure diagram of three systems a neat epoxy resin and the same epoxy modified with two reactive rubbers at the same concentration level. The times to the cloud point, gelation and vitrification are shown for each system. The cloud point is the point of incipient phase separation, as detected by light transmission. The modified system with the longer times to the cloud point and gelation, and the greater depression of Tg, contains the more compatible of the two rubbers. The difference in compatibility could then be used to account for differences in the volume fractions of the phase separated rubber-rich domains and in the mechanical properties of the neat and the two rubber-modified systems. 

Fig. 13. TXT cure diagram temperature of cure vs. the times to phase separation (doud point), gelation and vitrification for a neat and two rubber-modified systems. of the neat system is also included. The systems studied were DER331/TMAB O, gelation , vitrificaticm modified with IS parts rubber per hundred parts epoxy 1) pr eacted carboxyl-terminated butadiene-acrylonitrile (CTBN) copolymer containing 17% acrylonitrile (K-293, Spencer Kellog Co.) A, phase separation , gelation , vitrification, and 2) polytetramethylene oxide terminated with anmiatic amine (ODA2000, Polaroid Corp.) A. phase separation O, gelation O, vitrification. (DER331/TMAB/ K-293 data from Ref. )...

In this Section, an experimental approach for constructing isothermal TTT cure diagrams has been described, TTT diagrams of representative epoxy systems including high Tg and rubber-modified epoxy resins have been discussed, and perturbations to the TTT cure diagram due to thermal degradation and rubber modification have been illustrated. 

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