Epoxide equivalent weight measurements

In this paper we discuss the use of carbon-13 nmr to measure epoxide equivalent weights of epoxy resins based on the diglycidyl ether of bisphenol A (DGEBA). The results obtained to date indicate that the carbon-13 technique could be an attractive alternative to current methods. 

Epoxide equivalent weight. Temperature of measurement = 52°C. Temperature of measurement = 100° C. Durran s mercury method. 

The 4532 cm combination tone is reasonably free of interferences, and can be employed to measure oxirane ring concentrations for epoxy-coating resin systems during synthesis and crosslinking. With the use of low S/N FTIR supported by computer data manipulation, chloroform solutions of five commercially available resins were analysed for epoxide-equivalent weight and correlated with results obtained by perchloric acid titrations. The near-IR technique displays linearity for epoxy concentrations of 3.6-20.7 meq/1. Similar results were obtained via a serial concentration study, indicating that the technique is not strongly affected by matrix effects. 

The epoxide equivalent is a measure of the amount of epoxy groups. This is the weight of resin (in grammes) containing 1 gramme chemical equivalent epoxy. For a pure diglycidyl ether with two epoxy groups per molecule the epoxide... 

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