The phenomenon of the abnormal logarithmic time dependence of the polymer yield for solid-state polymerization

About the role played by mobile nanovoids in the stimulation of solid-state processes

“…Frozen center For the example of post polymerization of γ irradi ated acrylonitrile held for a long time at 156 K, the kinetic curve of this process in the form of a logarithmic time dependence of the yield of terminationless solid state polymerization at low (on the order of several per cent) conversions was calculated [12], which resulted in close agreement with the experimental data [7].…”

“…The validity of the solid state polymerization model under consideration was substantiated theoret ically by computer calculations of the kinetic charac teristics of this process at various conversions over a wide range of temperatures and times of observation [2,11,12]. In terms of the concepts described above, the chain process of solid state polymerization is described by the following system of equations: (1)…”

“…A solution to system (1)-(7) obtained using com puter techniques was used to describe the kinetics of post polymerization of acrylonitrile in the crystalline state radiation initiated at 77 K over a wide range of times (from 60 to 10 6 s) at various temperatures Т > 77 K [11,12]. A solution to (5)-(7) allowed us to calculate kinetic dependences for the decay of most mobile nanovoids (vacancies, the activation energy of the dif fusion of which was close to Е i ) under isothermal con ditions in collisions with other nanovoids that remained at time t. The concentration of the latter was A solution to (5)- (7) shows that the decay of mobile at a constant temperature Т 1 nanovoids with time in a solid monomer causes a decrease in the concentration of "live" active centers in the system studied and, as a con sequence, a decrease in the rate of terminationless polymerization, which is the effect of chain freezing.…”