Selection of Cure Conditions

3 SELECTION OF CURE CONDITIONS 9.3.1 Selection of the Initial Temperature 

One of the main problems in the selection of a cure cycle is to achieve control of the exothermic polymerization reaction, particularly for the case of large parts. The exothermic character of the polymerization reaction arises from the evolution of the Gibbs free energy  

For the polymerization to proceed spontaneously, AG 0. But AS 0, because the system evolves to a more ordered state (the number of configurations in which free monomers may be placed in space decreases by the introduction of covalent bonds among themselves) thus, the entropy change does not favor polymerization. Then, the only possibility of getting AG 0 is to have a significantly exothermic reaction (AH 0) to counterbalance the unfavorable entropy change. 

It is also possible to act over the heat generation factor. This can be decreased by diluting the formulation with fillers or fibers. But this depends 

But vitrification may be a problem when the cure is started at room temperature and no external heat source is provided (the only source of heat generation is the polymerization reaction). This is the case of UV (ultraviolet radiation), EB (electron beam), or X-ray curing processes. 

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