AbstractVinyl acetate (VAc), styrene (St), and methyl methacrylate (MMA) were irradiated in dilute solution at an absorbed dose rate of 0.5 Mrad/hr in the absence of oxygen at room temperature. In homogeneous systems, telomers are formed with a rate ∝ M1at monomer concentrations M>ca. 0.4M. The chain length (D.P..n) increases with increasing M. (D.P..n)−1depends over large ranges of M linearly on the ratio S/M (S = solvent) in accordance with the Mayo equation. These findings were obtained with VAc in methanol and with St in cyclohexane. In heterogeneous systems, telomer is formed at all monomer concentrations. The 100‐eV yield for telomer formation passes a maximum ofGT(–M)= 40 (MMA in 2‐propanol) andGT(–M)= 27 (MMA in cyclohexane) at the onset of polymer formation (M ∼ 3 vol‐). With the system St/2‐propanol,GT(–M)∼ 15 was found being independent of M. The molecular weightMn(telomer) increased from ca. 600 to ca. 1200 by increasing M up to 100 vol‐ (MMA/2‐propanol).Mn(telomer) does not depend on M in the other two cases (Mn∼ 500, MMA/cyclohex
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