The free radical polymerization of methyl methacrylate in bulk at 0 °C initiated by photochemical decay of azobis(cyclohexanenitrile) (ACN) is tested over the full range of conversion up to the glassy state. Rate constants of propagation, kp, and termination, kt, are evaluated by the rotating sector technique and after effect. Instantaneous degree of polymerization and efficiencies, /, are given for all conversions. The conversion dependence of f can be expressed by the self-diffusion of small molecules in a polymer matrix.Both rate constants depend on the conversion; kt for conversions near and beyond the onset of entanglement also depends on the chain length of the polymer radicals but becomes independent of this length at about 45% conversion. The diffusion processes describing the different stages of conversion are discussed.
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