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γ‐radiation‐induced telomerization of vinyl acetate, styrene, and methyl methacrylate
Author(s) -
Altmann O.,
Fehrmann U.,
Schnabel W.
Publication year - 1979
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1979.070230119
Subject(s) - cyclohexane , vinyl acetate , telomerization , methyl methacrylate , styrene , monomer , polymer chemistry , chemistry , solvent , propanol , yield (engineering) , methyl acetate , polymer , methanol , materials science , organic chemistry , copolymer , catalysis , metallurgy
Vinyl 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 ∝ [M] 1 at monomer concentrations [M] > ca. 0.4 M . The chain length ( D.P. . n ) increases with increasing [M]. ( D.P. . n ) −1 depends 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 of G T (–M) = 40 (MMA in 2‐propanol) and G T (–M) = 27 (MMA in cyclohexane) at the onset of polymer formation ([M] ∼ 3 vol‐%). With the system St/2‐propanol, G T (–M) ∼ 15 was found being independent of [M]. The molecular weight M n (telomer) increased from ca. 600 to ca. 1200 by increasing [M] up to 100 vol‐% (MMA/2‐propanol). M n (telomer) does not depend on [M] in the other two cases ( M n ∼ 500, MMA/cyclohexane; M n ∼ 700, St/2‐propanol).