Study of the polymerization of solid vinyl monomers using differential scanning calorimetry (original) (raw)
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Frontal radical polymerization of vinyl monomers in non-stationary mode is investigated theoretically. It is shown that the formation and the time of establishment of steady-state polymerization heat autowaves considerably depend on the initial temperature, T i . When T i is less than the adiabatic heating temperature (T a ), the excess heat and relatively high conversion foster front formation before the non-stationary one. Whereas, for T i > T a , steady-state frontal polymerization regime is established, when the heat flow from the outer source is considerably less than the heat evolving due to the chemical reaction.
The Chemical Engineering Journal
Frontal radical polymerization of vinyl monomers in non-stationary mode is investigated theoretically. It is shown that the formation and the time of establishment of steady-state polymerization heat autowaves considerably depend on the initial temperature, T i . When T i is less than the adiabatic heating temperature (T a ), the excess heat and relatively high conversion foster front formation before the non-stationary one. Whereas, for T i > T a , steady-state frontal polymerization regime is established, when the heat flow from the outer source is considerably less than the heat evolving due to the chemical reaction.
Inter- and intra-molecular interactions in anionic polymerization of polar vinyl monomers
2014
This review article presents the results on the nature of the active centers of propagation (AC) in anionic polymerization of polar vinyl monomers such as acrylates, methacrylates, vinyl nitriles and vinyl ketones and especially their interactions with donor-acceptor ligands, carried out in the Laboratory of Polymerization Processes of the Institute of Polymers, Bulgarian Academy of Sciences. Particular attention to the interactions involving AC with lithium and magnesium counter-ions was paid due to their strong tendency of interacting with a variety of ligands, as well as in reactions of self-association resulting in numerous possibilities of controlling the structure of the polymers as well as the composition of copolymers. The model compounds or “living”oligomers of polar vinyl monomers were studied intensively by using IR spectroscopy and conductometry. Their physicochemical characteristics in solution, before and after adding of ligands, were investigated. A typical feature is...
Peculiarities of establishment of steady-state frontal polymerization of vinyl monomers
Chemical Engineering Journal, 2009
Frontal radical polymerization of vinyl monomers in non-stationary mode is investigated theoretically. It is shown that the formation and the time of establishment of steady-state polymerization heat autowaves considerably depend on the initial temperature, T i . When T i is less than the adiabatic heating temperature (T a ), the excess heat and relatively high conversion foster front formation before the non-stationary one. Whereas, for T i > T a , steady-state frontal polymerization regime is established, when the heat flow from the outer source is considerably less than the heat evolving due to the chemical reaction.
Cationic polymerization of vinyl monomers initiated by 10‐methylphenothiazine cation radicals
Journal of Polymer Science Part A: Polymer Chemistry, 1994
A small quantity of 10‐methylphenothiazine cation radical (MPT.+), electrochemically prepared and stocked in acetonitrile solution, initiated cationic polymerizations of n‐butyl, t‐butyl, and 2‐methoxyethyl vinyl ethers and p‐methoxystyrene, while no initiation occurred for phenyl vinyl ether, styrene, methyl methacrylate, and phenyl glycidyl ether. 1H‐NMR studies of oligomers and low molecular weight compounds isolated from the reaction mixture for the polymerization of t‐butyl vinyl ether in the presence of a small amount of D2O indicated that electron transfer from the monomer to MPT.+ was involved in the initiation step. 1H‐ and 13C‐NMR and MO calculation implied that monomers with higher electron densities on the vinyl groups and with lower ionization potentials were more susceptible to the initiation of MPT.+. © 1994 John Wiley & Sons, Inc.
Influence of thermal initiation on the radical polymerization of unsaturated monomers
Journal of Polymer Science Part A: Polymer Chemistry, 1989
The effect of thermal initiation of the radical polymerization of unsaturated monomem has been analyzed by considering a kinetic scheme that includes thermal: and catalyst-induced formation of free radicals, propagation, and termination reactions. Expressions relating the different rate constants with the instantaneous monomer concentration are derived and they indicate the great influence of thermal initiation on the kinetic results. Application to a real case suggests that evaluation of k , and k , / k~/ 2 from experimental results using the method of dead-end polymerization may lead to erroneous values of these constants.
A calorimetric study of the self-polymerization of a commercial monomer: An incident investigation
2011
In this work the analysis of an incident in transport of dangerous goods is proposed. The objective of this study is to contribute to the determination of the causes that brought about the self-polymerization of commercial divinylbenzene (DVB 63%) contained in an isothermal container, in order to prevent this incident from happening in the future. Time and conditions during transport/storage of monomers (in particular storage temperature) are very important factors that affect their aptitude of self-polymerization. In particular one hypothesis has been investigated: that the quantity of oxygen in the tanker was insufficient to activate properly the inhibition mechanism. Consequently, the self-polymerization of DVB and the inhibition mechanism of 4-tert-Butylcatechol (TBC) have been studied as a function of temperature and monomer exposure to air with Differential Scanning Calorimetry and Adiabatic Calorimetry techniques.