| Abstract: | The photolysis of poly(ethylene terephthalate) films was studied in vacuo with light of wavelengths 2537 and 3130 A. A very stable filter system which cuts out the 3025 A. line was developed to isolate 3130 A. from a mercury spectrum. Despite the fact that the penetration of 2537 A. light was limited to a depth of a ca. 103 A. whereas 3130 A. light was more uniformly absorbed it was possible to demonstrate that the quantum yields for CO and CO2 formation were in agreement for the two wavelengths. Quantum yields for fractures and crosslinks were estimated by sol-gel analysis. An absorption maximum which develops near 13 μ after exposure of poly(ethylene terephthalate) to light or γ-rays was attributed to the formation of groups formed by elimination of CO and CO2. ESR spectra for trapped radicals were tentatively assigned to the components p-C6H3· and ·O? CH2? CH2? . It is suggested that the former radicals combine to form crosslinks. Quantum yields (× 104) with 3130 A. light are: CO, 6; CO2, 2; crosslinks, 5.5; trapped radicals, 1.5; With 2537 A. light, quantum yields are: CO, 6–9; CO2, 2–3; the network formed was not characterized as to crosslinks and fractures; trapped radicals were observed to exist but not determined. |
