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Many commercial polymers are currently prepared
by free-radical copolymerization of two and more monomers.
With increasing number $m$ of their types good prospects appear
for imparting to the products of the synthesis
a variety of service properties.
However, as $m$ grows, the extent of experimental investigations
to be performed for revealing optimum conditions for the process
of manufacturing of copolymers with desired properties
dramatically increases.
Establishing the dependence of these latter on initial stoichiometry
of monomers and the degree of their conversion
by straightforward exhaustive search of possible variants
within whole range of initial monomer mixture composition
presents rather tedious experimental task even for terpolymerization.
In the case of copolymerization of more than three monomers involved
the solution of this problem calls for substantially greater amount
of time consuming routine experimental work.
That is why in designing of processes of synthesis
of multicomponent copolymers the mathematical modeling method
proves to be of prime importance,
which enables a researcher to calculate promptly
the values of statistical characteristics of molecular structure
of these copolymers as well as to predict
some of their performance properties.
You could carry out this procedure for the products
of free-radical copolymerization of up to $m=6$ monomers
using the other program ``Copolymerization Explorer''
constituting present package.
The program ``Copolymerization Kinetics''
is intended to find the dependence of the copolymerization rate
on time or monomer conversion proceeding from experimental data
you obtained by either dilatometry or calorimetry technique.

Mathematical models underlying the programs of present package
are commonly recognized in polymer science.
The validity of the results,
which can be achieved by means of these programs,
is ensured by solid physico-chemical experimental verification
for great number of real systems.
Essential advantage of this package's programs,
favoring their ample usage in practice,
is the fact that necessary input parameters
(such, for instance, as reactivity ratios,
the Flory-Huggins parameters, glass transition temperatures)
characterize either homopolymers or binary copolymers.
The values of these parameters are presently available in literature
for many particular polymers
which provides you a possibility in many cases
to start working with the programs immediately
skipping preliminary stage of some additional experiments.



Examining copolymerization of particular monomers
you very often face with the necessity to determine the dependence
of their overall conversion $p$ or the rate of its alteration
on time $t$.
In order to theoretically find these kinetic curves
(integral or differential) you are supposed to have at your disposal
a reliable mathematical model of copolymerization
properly taking into account all its elementary reactions.
Here the situation qualitatively differs from that
taking place for the calculations of composition,
sequence distribution and composition inhomogeneity
of the copolymerization products.
All these statistical characteristics are governed at fixed conversion
exclusively by the rate constants of chain propagation reactions
and can be calculated theoretically provided the values
of the reactivity ratios are known.
However these characteristics turn out to be insufficient
when the necessity arises to calculate the dependence of $p$ or
$dp/dt$ on time.
The result here depends on the specific features
of all elementary reactions including those
of initiation and termination of chain.
These latter, being diffusion-controlled reactions,
were found to be complicated by various physical factors
whose accurate account proceeding from current concepts
of polymer science constitutes a considerable challenge.
No generally recognized kinetic model of chain termination reaction
is available so far even for homopolymerization.
That is why experimental methods remain as yet the most reliable ones
when finding the overall rate of copolymerization.

Among various experimental techniques for the construction
of the kinetic curve of copolymerization the gravimetric method
is the most straightforward one.
However its realization in practice suggests a considerable body
of time consuming work.
This disadvantage may be successfully obviated by resorting
to dilatometric or calorimetric technique which are commonly recognized
in investigations of the homopolymerization kinetics.
The program in hand will be of assistance to you in performing
analogous examination in case of copolymerization
of up to six monomers.
This program is intended for the construction of an experimental
kinetic curve of a copolymerization process
on the base of dilatometric and calorimetric data available.
Essentially, that no assumptions were made concerning the reactions
of chain initiation and termination.




The programs of the package have highly intuitive
user-friendly interface.
To try the ``Copolymerization Kinetics'' download
the archive, unzip it and run the Setup.
To get an idea of the potentialities
of the program load one of the predefined
base variants (by selecting {\bf Load Base Variant} option
in the {\bf File} menu)
and perform calculations by clicking on the {\bf Compute!}
menu.
Many of the special terms encountered in the programs
should be readily familiar to those dealing
with the free-radical copolymerization.
However, an extensive help is also provided
(the help file is located in the same directory
with the program).


Here is the list of programs currently present
in the ``Copolymerization for Windows'' software package:
\begin{itemize}
  \item  Copolymerization Explorer
  \item  Copolymerization Kinetics
\end{itemize}
If you want to get any additional information on
the package you may contact
Semion Kuchanov at kuchanov@orc.ru.



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Modified: Tue Jan 14 21:32:10 2003 GMT
Page accessed 1141 times since Mon Nov 16 21:06:19 2009 GMT