4 research outputs found
Analytical Solution of Free Radical Polymerization: Applications- Implementing Gel Effect Using AK Model
In this work, gel/glass/cage effects
using the Achillias and Kiparissides (AK) model has been incorporated
in the analytical solution (AS) obtained in our previous work. The
AK model is based on the Chiu, Carratt, and Soong (CCS) model and
free volume theory. The results of AS matched quite well with the
numerical solutions as well as with the experimental data for methyl
methacrylate (MMA). Various variables like termination kinetic coefficient,
initiator efficiency, macroradicals concentration profile matched
with the established published results. The work clearly demonstrates
that AS is sufficiently flexible to accommodate gel/glass/cage effects
explicitly although it was not primarily derived for these conditions.
This extends the practical usage of AS for the whole range of conversion
under isothermal conditions
Analytical Solution of Free Radical Polymerization: Derivation and Validation
An
elegant, simple, and exact analytical solution (AS) was obtained
for a large range of elementary steps with practical importance in
free radical polymerization. The AS matches excellently with the numerical
solution for the four cases of monomer–polymer systems studied
ranging from the slowest to the fastest. It works equally well for
different initiators, different initiator and monomer concentrations,
presence or absence of solvent, various solvent volume fractions,
and different temperatures. It also matches quite well with experimental
data reported in the literature. This AS is not only in line with
previous published solutions but also extends their applicability
in a natural way. Overall, the conceptual correctness as well as predictive
capabilities of the derived AS are established beyond doubt. This
AS has the potential to be used in various practical applications
such as model based process control, CFD simulations, and so forth
Analytical Solution of Free Radical Polymerization: Applications- Implementing Gel Effect Using CCS Model
This article presents the implementation
of the Chiu, Carratt, and Soong (CCS) gel/glass model in an analytical
solution (AS) derived for the free radical polymerization under isothermal
condition. This implantation allows AS to be applicable for the whole
range of conversion thus making it more useful for practical applications.
The results were compared with numerical solution (NS) as well as
with experimental data for two different monomers: styrene (St) and
methyl methacrylate (MMA). MMA with chain transfer agent was also
used for this purpose. The results were found to be in good agreement
with both NS and experimental data. NS with and without quasi-steady
state assumption were also found to be in good agreement with each
other for the entire range of conversion. As constant time step was
used, the effect of stiffness on AS during gel effect was visible
at low temperature compared to higher temperature
Coil Flow Inversion as a Route To Control Polymerization in Microreactors
Linear and branched polymers of 2-(dimethylamino)ethyl
methacrylate
(PDMAEMA) were synthesized in flow by atom transfer radical polymerization
(ATRP) and self-condensing vinyl copolymerization adapted to ATRP,
respectively, in capillary type stainless steel coiled tube (CT) microreactors.
Coil flow inversion (CFI) was introduced to achieve better mixing
and narrower residence time distributions during polymerization. This
strategy was adopted to improve control over macromolecular characteristics
and polymer architecture. Polydispersity index (PDI), as an overall
indicator of control over polymerization, was significantly lower
for CFI in the case of linear PDMAEMA, 1.39 compared to 1.53 for CT.
For branched polymers containing up to 10 mol % of inimer, a reduced
PDI was also obtained for CFI microreactor. As for the branching efficiency,
it was found to follow the following trend CFI > CT > batch
reactor