Polycarbonate infrared spectra

Fig. 23. Infrared spectrum of polycarbonate 1, unirradiated 2, irradiated 120 h 3, spectrum of the yellow product isolated after complete hydrolysis of irradiated polycarbonate [reproduced with permission from Ref. 108].

The infrared spectrum of the residue of polycarbonates subjected to pyrolysis at 500°C contains no bands characteristic of methyl groups the intensity of the absorption bands of the ester groups -C = O and -C-O-C-is significantly reduced, and the absorption bands corresponding to the benzene ring are intensified. 

The PA spectrum shown in Figure 14.6 was obtained from the top of a screw made from a polycarbonate material. As this sample was hard and had a complicated structure, it was not possible to measure a high-quality mid-infrared spectrum by other methods. The accumulation time for recording the spectrum shown in Figure 14.6 was 20 s, and it is often possible to measure PA spectra having signal-to-noise (S/N) ratios at this level in such a relatively short period. 

Optical Constants of Blsphenol—A Polycarbonate In the Infrared. The spectral values obtained for n and k of BPA-PC between 2000 and 950 cm"" are plotted In Fig. 4. In the 3200-2800 cm region, which encompasses the C-H stretching region of the spectrum (not shown), the expected variations In n and k were too small to be detectable above the level of random noise. A constant value of n =1.39 was measured within the higher wave-number region. 

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