Free Radical Pairs Produced by Irradiation of Polymers with Ionizing Radiation

3 Free Radical Pairs Produced by Irradiation of Polymers with Ionizing Radiation 

The pair-wise formation of radicals in polymer materials is important as an elementary process for radical formation by irradiation. Iwasaki et al. [17] found direct evidence for pair-wise formation in various polymers. 

These results indicate that the outer parts of the Ams = 1 spectrum undoubtedly comes from the radical pairs. When the magnetic field (Ho) was parallel to the chain axis, the fine splitting, d, was easily determined to be 37.1 mT. The splitting d (mT) changes with the orientation according to the equation  

Using the crystallographic data for polyethylene, the values of r and 0 can be calculated for various sets of radical pairs and the corresponding values of d are compared with the observed value, 37.1 mT. The observed radical pair is of the intra chain type which is produced four bonds apart in the same chain —CH2— (C OH—CH2—CH2—CH2—(C )H—CH2—. The calculated distance between the pair is 0.510 nm, which is close to the observed value, 0.531 nm (5.31 A). 

---

B-4) Free radical pairs produced by irradiation of polymers with ionizing radiation and the distance between the paired radicals. 

---