Isothermal curing reactions

Figure 2.26 DSC scans of the isothermal curing reaction of vinyl ester at various temperatures.

Widmann G, Isothermal curing reactions of an epoxy resin. Thermal analysis, Vol 3, Proc of the 4th ICTA, Budapest, 359, 1974. 

Gel time values of the three systems measured as abrupt change in the slope of G (t) under isothermal curing conditions show that gelation occurs earlier in PWE system at all temperatures considered as shown in Table 11.27. ETPI behaves like a catalyst for the primary epoxy-amino reaction which dominates the cure until vitrihcation occurs. Dynamic mechanical analysis and dielectric spectroscopic analysis carried out by the authors also confirm the above conclusions. 

Modification of the FT-IR analysis techniques to analyze coatings under isothermal cure conditions provides the data needed to determine the rate constants for each reaction. An effective method to generate the rate constants from the experimental data has been found and will be described. 

Figure 3.19 Reaction paths undergoing phase separation during isothermal cure...

In situ frequency dependent electromagnetic-impedence measurements provide a sensitive, convenient, automated technique to monitor the changes in macroscopic cure processing properties and the advancement of the reaction in situ in the fabrication tool. This chapter discusses the instrumentation, theory, and several applications of the techniques, including isothermal cure, complex time—temperature cure, resin film infusion, thick laminates, and smart, automated control of the cure process. 

If the curing reaction occurs at adiabatic or isothermal conditions above the glass transition temperature of the ultimately cured polymer, the reaction kinetics is adequately described by the adopted mechanism 5> 16,l7 69 7i However, at temperatures substantially below the final glass transition temperature, the reaction rate at a certain... 

Curing reactions Vulcanisation reactions Isothermal ageing Product stability Thermal degradation Identification of processing aids Plasticisers Mould lubricants Blowing agents Antioxidants Flame retardants Safety concerns... 

On isothermal reaction above Tg, the material will gel but not vitrify in the absence of degradation. An elastomer (gel rubber) is formed above Tg after prolonged isothermal cure, as indicated by the full cure line. 

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