Radiation-induced unsaturation loss

An IR study was made of the radiation-induced loss of unsaturation and methyl production in 1,2-polybutadiene (VB). G(-l,2), which depends on... 

Figure 3 presents a superposition of kinetic data for the radiation-induced loss of 1,2 unsaturation in VB, the data having been normalized for the different initial vinyl contents in the various polymers. The residual unsaturation-dose data for Polymer A were plotted directly, yielding the solid line shown data for Polymers B, C and 6 were arbitrarily plotted at doses greater than the actual doses by amounts equal to shift factors of 2.0, 2.7 and 3.0 Mrad, respectively. These shift factors correspond to the doses required to decrease the 1,2 unsaturation of Polymer A from 98.5% initially to 90.1, 86.0 and 85.0% (the initial vinyl contents of Polymers B, C and 6), respectively. By this normalization procedure, the data for the three VB polymers used in this work (A, B and C) and the single data point available from the literature (Polymer 6) could be fitted to a common kinetic plot. From the initial slope to the solid line in Figure 3, Gg(-1,2) was found to have the rather high value of t SSO. Taking the tangent to the line at 85% 1,2, we obtain G3.q(-1,2) 270, which compares...

Figure 3. Superposition of kinetic data for radiation-induced loss of 12-unsaturation in polybutadiene with different initial vinyl content. Key O, 98.5% unsaturation CD, 90.1% unsaturation , 86.0% unsaturation and , 85.0% unsaturation.

In later studies, Golub and Danon [329, 330] reported that, in addition to loss of unsaturation, polybutadiene and polyisoprene films and solutions undergo radiation-induced cis-trans isomerization. 

---