Epoxy resin cure reaction

Barton, J. M. The Application of Differential Scanning Calorimetry (DSC) to the Study of Epoxy Resins Curing Reactions. Vol. 72, pp. 111 — 154. 

In Chapter 2 the DSC technique is discussed in terms of instruments, experimental methods, and ways of analysing the kinetic data. Chapter 3 provides a brief summary of epoxy resin curing reactions. Results of studies on the application of DSC to the cure of epoxy resins are reviewed and discussed in Chapter 4. These results are concerned with the use of carboxylic acid anhydrides, primary and secondary amines, dicyanodiamide, and imidazoles as curing agents. 

Although the simple rate expressions, Eqs. (2-6) and (2-9), may serve as first approximations they are inadequate for the complete description of the kinetics of many epoxy resin curing reactions. Complex parallel or sequential reactions requiring more than one rate constant may be involved. For example these reactions are often auto-catalytic in nature and the rate may become diffusion-controlled as the viscosity of the system increases. If processes of differing heat of reaction are involved, then the deconvolution of the DSC data is difficult and may require information from other analytical techniques. Some approaches to the interpretation of data using more complex kinetic models are discussed in Chapter 4. 

In general the amine-epoxy resin curing reactions show complex kinetics typified by an initial acceleration due to autocatalysis, while the later post-gelation stages may exhibit retardation as the mechanism becomes diffusion-controlled. However some workers 72 80) have found that over a limited range of conversion the kinetic data may be described by the simple models of Eq. (2-6) or (2-9). 

Levy, N. Analysis of an epoxy resin curing reaction by differential scanning calorimetry, in Computer Applications in Applied Polymer Science, p. 313, ACS Symp. Ser. 197, Washington D.C., Amer. Chem. Soc. 1975... 

Therefore, catalysts merely act as an initiator and promoter of epoxy resins curing reactions. The amounts of catalyst used with epoxy resins are usually determined empirically and are chosen to give the optimum balance of properties under the required processing conditions. Generally, only several parts per hundred of catalyst is used with an epoxy resin. Excess amounts of catalyst can result in poor physical properties and degraded resin. 

Barton, J. M. (1985) The application of DSC to the study of epoxy resins curing reactions, in Dusek, K. (Ed.) Applied Polymer Science - Epoxy Resins and Composites I, Berlin Springer-Verlag. Bauer, C., Amram, B., Agnely, M. et al. (2000) Appl. Spectrosc., 54, 528-535. 

BUlaud, C., R. Legras, and V. Carher, Quantitative Analysis of Epoxy Resin Cure Reaction A Study by Near-Infrared Spectroscopy. A/ / /. Spectrosc., 2002. 56 1413-1421. 

Keywords Liquid crystalline thermosets, liquid crystalline epoxy resins, curing reactions, mechanical properties, thermal properties... 

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