Kinetics of styrene polymerization at ultrahigh conversion

Abstract

The radical‐initiated bulk polymerization of styrene at low conversion can be adequately described by a simple kinetic scheme that involves initiation by the decomposition of a radical initiator, propagation, and termination by combination of polystyryl radicals. An integrated equation can be derived that will describe the relationship between monomer concentration and time. We have investigated the validity of applying equations of this kind in the 98–99.999% conversion range. From our experimental work we conclude that the initial rates at 130°C, when starting the polymerization at that temperature at more than 98% conversion, can be described by an integrated equation over at least two decades of monomer concentration. Deviations from the simple kinetics at ultrahigh conversion were observed after a certain time at 130°C. These are discussed and explained in terms of the kinetic assumptions made and an extended model is suggested to allow for depolymerization reactions that cannot be neglected at ultrahigh conversion.

Photoinitiated miniemulsion polymerization in microfluidic chips on automated liquid handling stations: Proof of concept

“…The photolysis of benzophenone and Irgacure® 819 is characterized by the generation of benzoyl radicals, another potential species that could participate in depolymerization reactions at longer irradiation times . According to Kwant, depolymerization as the reverse reaction of chain propagation in styrene polymerization becomes significant in the range of rather high conversion, because diffusion limitations lower the rate constant of the propagation reaction significantly .…”

Dynamic mechanical properties and morphology of styrene-divinylbenzene copolymer/poly(vinyl chloride) systems. (II). Effect of polymerization temperature

“…The P(St-DVB) phase has the heterogeneity in the cross-linking density due to the difference of the copolymerizability of the first double bond of DVB with St from that of the second one. 6 And the cross-linking density of this phase is much higher than that estimated from the DVB/(St + DVB) ratio in the recipe. The reason for this phenomenon was ascribed to the difference of the diffusion constants of St and DVB into PVC particles on the paste formation and the polymerization proce~s.~ Assuming that the phaseseparated structure of P(St-DVB)/PVC systems is derived from the difference of the diffusion constants of monomers, the temperature dependences of the diffusion constants of St and DVB into PVC particles should have an effect on the structures of P(St-DVB)/PVC systems polymerized at different temperatures.…”

Free‐radical polymerization kinetics of methyl methacrylate at very high conversions

“…(24) for modelling polymerizations of MMA at very high conversions, but with less success than with Eq. (19). In every case the minimized sum of the squared differences between experimental and predicted conversions was smaller with Eq.…”

“…In every case the minimized sum of the squared differences between experimental and predicted conversions was smaller with Eq. (19). Moreover Eq.…”

“…By combining Eqs. (l), (3), (lo), and (14) - (19) expressions for kp and [P*] as a function of conversion (and temperature) can be deduced and inserted into Eq. (7).…”