Comparison of Calculated Rates to Other Methods for Polyethylene Films

5 COMPARISON OF CALCULATED RATES TO OTHER METHODS FOR POLYETHYLENE FILMS 

The diffusion coefficients of A,A-diaIkylanilines (where alkyl was varied from methyl to dodecyl) in unstretched or stretched PE films have been measured using methods 

FIGURE 13.5 Radical pairs from irradiation of (R)-lb and (R)-3b showing their relative positions at their moments of formation. Adapted from Ref. 77 by permission of the Royal Society of Chemistry on behalf of the European Society for Photobiology and the European 

Using the D values of the dialkylanilines at 298K and Equation 13.13, the time required for 1-phenylethyl and 1-naphthoxy radicals to move to the locations amenable to combine at the 2- and 4-positions of 1-naphthoxy, ca. 3.1 and 5.0 A, respectively, correspond to ca. 2.4-24 and 6.3-63 ns in unstretched PEG and ca. 24—240 and 63-630 ns in unstretched PE46, depending on the specific diffusion coefficient employed. The times required for formation of the keto intermediates of 2-AN and 4-AN from lb by the radical clock method described above are ca. 3 and 14 ns, respectively, in unstretched or sttetched PEG and ca. 2-3 and 26-33 ns, respectively, in unstretched LDPE. In stretched LDPE, where translocation increases 

DYNAMICS OF RADICAL PAIR PROCESSES IN BULK POLYMERS 

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