Acrylics, determination Epoxy groups

Swaraj and Ranby used infrared spectroscopy to determine epoxy groups in methylmethacrylate - glycidyl methacrylate copolymers. The analysis was performed on dried potassium bromide pellets containing 0.5 mg sample in 200 mg potassium bromide. The peaks at the wavenumbers 907 (11.02 u) and 1717 cm (5.82 u) are the most suitable ones for analysis of epoxy and carbonyl groups respectively. Using the base line density method the values of the absorbances at 907 and 1717 cm" wavenumbers were determined. The average values of the absorbances, their ratio and the glycidylmethyl-acrylate mole fraction determined chemically are presented in Table 2.8. 

Real Time (RT-) FTIR spectroscopy pormits not only to follow quantitatively the polymerization by monitoring the disappearance of the IR absorption characteristic of the polymerizable reactive groups (acrylates, methacrylates, epoxy rings, vinyl ether double bonds, thiol groups etc.) but also to determine at any moment the actual degree of conversion and hence the residual imreacted groups content. This analytical method has proved extremely valuable for measuring the polymerization rates and quantum yields of reactions that develop in the millisecond time scale. 

The determination of carboxyl, ester and epoxy groups in various acrylic copolymers is discussed in Section 2.7.1. In many cases such analyses enable copolymer analysis to be carried out. 

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