U.S. patent application number 14/019294 was filed with the patent office on 2014-01-02 for polymer processing simplification.
This patent application is currently assigned to Honeywell International Inc.. The applicant listed for this patent is Honeywell International Inc.. Invention is credited to Hang T. Pham, George J. Samuels, Gregory J. Shafer.
Application Number | 20140005335 14/019294 |
Document ID | / |
Family ID | 39563199 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140005335 |
Kind Code |
A1 |
Samuels; George J. ; et
al. |
January 2, 2014 |
POLYMER PROCESSING SIMPLIFICATION
Abstract
A process for the preparation of a fluoroolefin polymer from an
azeotropic mixture of monomers having a constant composition, the
process including the step of: contacting in a reaction zone: (i)
an initiator; and (ii) an azeotropic mixture of monomers including
at least one fluoroolefin and, optionally, at least one
ethylenically unsaturated comonomer capable of copolymerizing
therewith; wherein the contacting is carried out at a temperature,
pressure and length of time sufficient to produce the fluoroolefin
polymer.
Inventors: |
Samuels; George J.;
(Williamsville, NY) ; Shafer; Gregory J.; (Newark,
DE) ; Pham; Hang T.; (Amherst, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Honeywell International Inc. |
Morristown |
NJ |
US |
|
|
Assignee: |
Honeywell International
Inc.
Morristown
NJ
|
Family ID: |
39563199 |
Appl. No.: |
14/019294 |
Filed: |
September 5, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11961087 |
Dec 20, 2007 |
8552128 |
|
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14019294 |
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60871035 |
Dec 20, 2006 |
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Current U.S.
Class: |
525/199 ;
526/249 |
Current CPC
Class: |
C08L 27/12 20130101;
C08F 214/18 20130101; C08L 27/12 20130101; C08L 2666/04 20130101;
C08F 214/18 20130101; C08L 2205/02 20130101; Y02P 20/582 20151101;
C08F 214/24 20130101; C08L 2666/04 20130101; C08F 2/00
20130101 |
Class at
Publication: |
525/199 ;
526/249 |
International
Class: |
C08F 214/24 20060101
C08F214/24; C08L 27/12 20060101 C08L027/12 |
Claims
1-23. (canceled)
24. A homopolymer prepared by a process comprising a step of:
contacting in a reaction zone: an initiator; and an azeotropic
mixture of at least two monomers comprising at least one
fluoroolefin and, optionally, at least one ethylenically
unsaturated comonomer capable of copolymerizing therewith; wherein
said contacting is carried out at a temperature, pressure and
length of time sufficient to produce said fluoroolefin polymer.
25. A copolymer prepared by a process comprising a step of:
contacting in a reaction zone: an initiator; and an azeotropic
mixture of at least two monomers comprising at least one
fluoroolefin and, optionally, at least one ethylenically
unsaturated comonomer capable of copolymerizing therewith; wherein
said contacting is carried out at a temperature, pressure and
length of time sufficient to produce said fluoroolefin polymer.
26. A terpolymer prepared by a process comprising a step of:
contacting in a reaction zone: an initiator; and an azeotropic
mixture of at least two monomers comprising at least one
fluoroolefin and, optionally, at least one ethylenically
unsaturated comonomer capable of copolymerizing therewith; wherein
said contacting is carried out at a temperature, pressure and
length of time sufficient to produce said fluoroolefin polymer.
27. A polymer blend comprising at least two polymers selected from
the group consisting of: a homopolymer, copolymer, and terpolymer
prepared by a process comprising a step of: contacting in a
reaction zone: an initiator; and an azeotropic mixture of at least
two monomers comprising at least one fluoroolefin and, optionally,
at least one ethylenically unsaturated comonomer capable of
copolymerizing therewith; wherein said contacting is carried out at
a temperature, pressure and length of time sufficient to produce
said fluoroolefin polymer.
Description
CROSS-REFERENCE TO A RELATED APPLICATION
[0001] The present application claims priority from U.S.
Provisional Patent Application No. 60/871,035, filed Dec. 20, 2006,
which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to a process for
making fluoroolefin homopolymers, copolymers, terpolymers, and
blends thereof, employing a single feed of an azeotropic mixture of
monomers having a constant composition wherein the azeotropic
mixture of monomers includes at least one fluoroolefin and
optionally, a comonomer capable of copolymerizing therewith. More
particularly, the present invention relates to fluoroolefin
homopolymers, copolymers, terpolymers, and blends thereof, prepared
by the present process, which employs the azeotropic mixture of
monomers of the present invention.
[0004] 2. Description of the Prior Art
[0005] Fluorine-containing polymers and copolymers are described in
U.S. Pat. No. 2,970,988. Vinylidene fluoride copolymers are
described in U.S. Pat. No. 3,893,987 (see Example 2) and process is
described in U.S. Pat. No. 3,240,757. VDF/CTFE copolymers are
described in U.S. Pat. No. 5,292,816 and U.S. Pat. No. 3,053,818
(see Example 6).
[0006] Other copolymers made from fluoroolefins are described in
U.S. Pat. Nos. 3,812,066; 2,599,640; 6,342,569; 5,200,480; and
2,919,263.
[0007] Fluorocarbon/Acrylate Coatings are described in U.S. Pat.
No. 3,716,599 and powder coating are described in U.S. Pat. No.
5,030,394.
[0008] Solvent based blending is described in U.S. Pat. No.
3,324,069. Polyvinylidene fluoride/polymethyl methacrylate blends
are described in U.S. Pat. No. 6,362,271. Other blends are
described in U.S. Pat. Nos. 5,051,345; 5,496,889 (Compatibilized
Blends); U.S. Pat. No. 4,990,406 (F-terpolymer/acrylate blends).
Graft Copolymers are described in U.S. Pat. No. 4,308,359.
[0009] Use of fluoro monomers as thermal stress-crack relievers is
described in U.S. Pat. No. 3,847,881. 2-Chloropentafluoropropene is
described in U.S. Pat. No. 2,915,510 (see Example 4); U.S. Pat. No.
2,917,497 (see Example 11); and U.S. Pat. No. 2,975,164 (see
Example 7).
[0010] However, none of these references describes preparation of
fluorine-containing polymers, copolymers, terpolymers, and blends
thereof, prepared by a process, which employs an azeotropic mixture
of monomers having a constant composition as the feed stream.
[0011] In view of the high cost of the fluoro monomer starting
materials, there is a need in industry to develop a general and
commercially feasible process for making such fluorine-containing
polymers and exploring their properties and uses in various
applications.
[0012] To achieve this objective, the present invention provides a
practical process, which is capable of introducing the reactants
into the reaction zone in a single stream having a constant
composition.
[0013] For this reason, the process according to the present
invention is potentially useful commercially.
SUMMARY OF THE INVENTION
[0014] The present invention provides a process for the preparation
of a fluoroolefin polymer from an azeotropic mixture of monomers
having a constant composition.
[0015] The process including the step of: [0016] contacting in a
reaction zone: [0017] (i) an initiator; and [0018] (ii) an
azeotropic mixture of monomers including at least one fluoroolefin
and, optionally, at least one ethylenically unsaturated comonomer
capable of copolymerizing therewith; [0019] wherein the contacting
is carried out at a temperature, pressure and length of time
sufficient to produce the fluoroolefin polymer.
[0020] The process according to the present invention is capable of
introducing the reactants into the reaction zone in a single stream
having a constant composition and, as such, it is practical, and
has the potential to be useful commercially.
[0021] These and other benefits of the present invention will
become more evident from detailed description of the preferred
embodiments that follow.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention provides a process for the preparation
of a fluoroolefin polymer from an azeotropic mixture of monomers
having a constant composition.
[0023] The process includes the step of contacting in a reaction
zone an initiator and an azeotropic mixture of at least two
monomers comprising at least one fluoroolefin and, optionally, at
least one ethylenically unsaturated comonomer capable of
copolymerizing therewith.
[0024] The step of contacting is carried out at a temperature,
pressure and length of time sufficient to produce said fluoroolefin
polymer.
[0025] The reaction zone can further comprises a solvent selected
from ethyl acetate, butylacetate, toluene, xylene, methyl ethyl
ketone, 2-heptanone, 1-methoxy-2-propanol acetate,
1,1,1-trichloroethane and mixtures thereof.
[0026] In a preferred embodiment of the present process, the
azeotropic mixture of the monomers comprise at least two
fluoroolefin monomers selected from fluoroolefins represented by
the formula:
R.sup.1R.sup.2C.dbd.CR.sup.3R.sup.4 [0027] wherein each of R.sup.1,
R.sup.2, R.sup.3, and R.sup.4 is independently selected from
hydrogen, chloro, fluoro, hydroxy, alkoxy, alkoxycarbonyl, acyl,
cyano, linear, branched or cyclic alkyl of 1-6 carbon atoms
optionally substituted by at least one fluorine, aryl of 1-6 carbon
atoms optionally substituted by at least one fluorine, with the
proviso that at least one of the R.sup.1, R.sup.2, R.sup.3, and
R.sup.4 groups is either fluorine or a fluorine-containing
group.
[0028] Examples of the fluoroolefin monomer include
CF.sub.3CF.dbd.CF.sub.2, CF.sub.3CH.dbd.CF.sub.2,
CF.sub.3CF.dbd.CHF, CF.sub.3CH.dbd.CH.sub.2,
CF.sub.3CF.dbd.CH.sub.2, CF.sub.3CF.sub.2CF.dbd.CF.sub.2,
CF.sub.3CF.sub.2CH.dbd.CF.sub.2, CF.sub.3CF.sub.2CF.dbd.CHF,
CF.sub.3CF.sub.2CH.dbd.CH.sub.2, CF.sub.3CF.sub.2CF.dbd.CH.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CF.sub.2,
CF.sub.3CF.sub.2CF.sub.2CH.dbd.CF.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CHF,
CF.sub.3CF.sub.2CF.sub.2CH.dbd.CH.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CH.sub.2, CF.sub.3CH.dbd.CHCF.sub.3,
CF.sub.3CH.dbd.CFCF.sub.3, CF.sub.3CF.dbd.CFCF.sub.3,
HOCH.sub.2CH.dbd.CHF, HOCH.sub.2CH.dbd.CF.sub.2,
HOCH.sub.2CF.dbd.CH.sub.2, HOCH.sub.2CF.dbd.CHF,
HOCH.sub.2CF.dbd.CF.sub.2, HOCH.sub.2CF.dbd.CH.sub.2,
CF.sub.3CH.dbd.CHCl, CF.sub.3CCl.dbd.CH.sub.2, CF.sub.3CCl.dbd.CHF,
CF.sub.3CCl.dbd.CF.sub.2, CF.sub.3CF.dbd.CHCl, CF.sub.3CH.dbd.CFCl,
CF.sub.2.dbd.CFCl, CF.sub.2.dbd.CF.sub.2, CF.sub.2.dbd.CH.sub.2,
CFH.dbd.CH.sub.2 and mixtures thereof.
[0029] Examples of the ethylenically unsaturated comonomer include
fluoroolefin monomers or an alkene of 2-8 carbon atoms, acrylate or
methacrylate ester of 4 to 24 carbon atoms, acrylonitrile,
methacrylonitrile, vinyl ether, styrene, alpha-methylstyrene,
paramethyl styrene, allyl alcohol, methallyl alcohol, vinyl
acetate, vinyl carboxylate of 5-24 carbon atoms, methyl ethyl
ketone, and mixtures thereof.
[0030] Examples of the acrylate or methacrylate ester is selected
from the group consisting of: methyl acrylate, ethyl acrylate,
propyl acrylate, butyl acrylate, ethylhexylacrylate,
methylmethacrylate, ethylmethacrylate, butylmethacrylate,
ethylhexymethacrylate, and mixtures thereof.
[0031] Preferably, the fluoroolefin monomer is from about 30 wt %
to about 70 wt % of the total weight of the polymer and the
ethylenically unsaturated comonomer is from about 70 wt % to about
30 wt % of the total weight of the polymer.
[0032] In another preferred embodiment of the present process, the
azeotropic mixture of the monomers comprise at least two
fluoroolefin monomers, each of the fluoroolefin monomers being
selected from a fluoroolefin represented by the formula:
R.sup.1R.sup.2C.dbd.CR.sup.3R.sup.4 [0033] wherein each of R.sup.1,
R.sup.2,R.sup.3, and R.sup.4 is independently selected from
hydrogen, chloro, fluoro, hydroxy, alkoxy, alkoxycarbonyl, acyl,
cyano, linear, branched or cyclic alkyl of 1-6 carbon atoms
optionally substituted by at least one fluorine, aryl of 1-6 carbon
atoms optionally substituted by at least one fluorine, with the
proviso that said fluoroolefin has at least one fluorine.
[0034] Examples of the fluoroolefin monomer include
CF.sub.3CF.dbd.CF.sub.2, CF.sub.3CH.dbd.CF.sub.2,
CF.sub.3CF.dbd.CHF, CF.sub.3CH.dbd.CH.sub.2,
CF.sub.3CF.dbd.CH.sub.2, CF.sub.3CF.sub.2CF.dbd.CF.sub.2,
CF.sub.3CF.sub.2CH.dbd.CF.sub.2, CF.sub.3CF.sub.2CF.dbd.CHF,
CF.sub.3CF.sub.2CH.dbd.CH.sub.2, CF.sub.3CF.sub.2CF.dbd.CH.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CF.sub.2,
CF.sub.3CF.sub.2CF.sub.2CH.dbd.CF.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CHF,
CF.sub.3CF.sub.2CF.sub.2CH.dbd.CH.sub.2,
CF.sub.3CF.sub.2CF.sub.2CF.dbd.CH.sub.2, CF.sub.3CH.dbd.CHCF.sub.3,
CF.sub.3CH.dbd.CFCF.sub.3, CF.sub.3CF.dbd.CFCF.sub.3,
HOCH.sub.2CH.dbd.CHF, HOCH.sub.2CH.dbd.CF.sub.2,
HOCH.sub.2CF.dbd.CH.sub.2, HOCH.sub.2CF.dbd.CHF,
HOCH.sub.2CF.dbd.CF.sub.2, HOCH.sub.2CF.dbd.CH.sub.2,
CF.sub.3CH.dbd.CHCl, CF.sub.3CCl.dbd.CH.sub.2, CF.sub.3CCl.dbd.CHF,
CF.sub.3CCl.dbd.CF.sub.2, CF.sub.3CF.dbd.CHCl, CF.sub.3CH.dbd.CFCl,
CF.sub.2.dbd.CFCl, CF.sub.2.dbd.CF.sub.2, CF.sub.2.dbd.CH.sub.2,
CFH.dbd.CH.sub.2, and mixtures thereof.
[0035] The azeotropic mixture of the monomers has a constant
composition so that the azeotropic mixture of the monomers can be
advantageously introduced as a single feed into the reaction
zone.
[0036] The starting materials are known in the art and are
generally available from commercial sources. Others can be prepared
by known methods described in the chemical literature. For example,
CF.sub.3CH.dbd.CHF can be made in large scale from commercially
available CF.sub.3CH.sub.2CF.sub.2H according to methods described
in U.S. Pat. No. 6,548,719 B1. CF.sub.3CH.sub.2CF.sub.2H is
produced by and is available from Honeywell International, Inc.,
Morristown, N.J.
[0037] Preferably, CF.sub.3CH.dbd.CF.sub.2 is formed from
CF.sub.3CH.sub.2CF.sub.2H by chlorination followed by
dehydrochlorination and CF.sub.3CH.dbd.CHF is formed from
CF.sub.3CH.sub.2CF.sub.2H by dehydrofluorination.
[0038] The step of contacting is typically carried out at a
temperature, pressure and length of time sufficient to produce the
desired fluoroolefin polymer.
[0039] The contacting is preferably carried out at a temperature
from about 10.degree. C. to about 80.degree. C. and more preferably
from about 20.degree. C. to about 65.degree. C. The contacting is
preferably carried out at a pressure from about 50 psig to about
500 psig and more preferably about 85 psig to about 260 psig. The
contacting is preferably carried out for a length of time from
about 4 hours to about 20 hours and more preferably for about 6
hours to about 12 hours.
[0040] Another aspect of the process of the invention is use of
selected free-radical initiators. Common initiators used for free
radical polymerization of unsaturated monomers are generally
satisfactory in the process of the invention depending on the
nature and properties desired. For example, azo-type initiators
result in high polydispersity in the molecular weight distribution
whereas perester type peroxides produce a narrow molecular weight
distribution and, as such, are preferably used in most cases.
[0041] Examples of the initiator include azobiscyanoacrylates,
aliphatic peresters, such as, t-butyl peroctoate and t-amyl
peroctoate, aliphatic peroxides, such as, tert-butyl peroxide,
aliphatic hydroperoxides, such as, tert-butyl hydroperoxide,
inorganic peroxides such as sodium peroxide, inorganic persulfates
such as potassium persulfate, redox initiators involving
persulfates as oxidant and sulfites such as sodium metabisulfite as
reductant, percarbonates such as t-butylperoxide-2-ethyl
hexylcarbonate, peroxydicarbonates, perhaloacetyl peroxides and
mixtures thereof.
[0042] Generally, the perester initiator is used at a concentration
of less than 20 weight percent based on the weight of the total
monomers, usually the perester initiator is used at concentrations
less than 12 weight percent, with a range of from 0.1 to 1.0 weight
percent being preferred.
[0043] Preferably, the perester initiator is added to the reaction
zone together with the monomeric reactants, i.e., the azeotropic
mixture of monomers, as previously stated. However, a minor amount
of peroxide as a finishing step may be added after the
polymerization reaction has substantially ended. Such a finishing
step has the purpose of removing minor amounts of unreacted
monomers and aids in achieving a reaction zone product that may be
used directly for the desired end use or applicationn.
[0044] Thus, it is important that at least 50, and preferably at
least 80, weight percent of the peroxide to be added with the
monomers and the balance of the initiator added during the
polymerization reaction.
[0045] The polymerization process may be conducted in the presence
of tertiary amine or a tertiary mercaptan-type chain transfer
agent. The use a chain transfer agent may result in a copolymer of
suitable molecular weight to have the required organic solvent
solubility.
[0046] Generally, the chain transfer agent is used at a
concentration of less than 5 weight percent based on the weight of
monomers added to the reaction zone.
[0047] The reaction zone preferably has provision for agitation and
heat exchange to assist uniformity and process control.
[0048] The process can be carried out as a continuous, batch, vapor
phase, liquid phase, fixed bed, solution, emulsion, or a suspension
type of a polymerization process.
[0049] The reaction zone can further include a diluent, such as, a
solvent or mixture of solvents. Solvents used in non-aqueous
polymerization methods are preferably, non-polar, non-reactive,
non-polymerizable, non-protic solvents are used as the reaction
medium. However, other solvents, such as, non-interfering
non-polymerizable liquid which is a solvent both for the monomers
and copolymer products of the invention. Suitable reaction solvents
include esters, ketones, ethers, aromatic hydrocarbons, chlorinated
hydrocarbons, aliphatic hydrocarbons, and mixtures thereof.
Illustrative solvents are ethyl acetate, butylacetate, toluene,
xylene, methyl ethyl ketone, 2-heptanone, and
1,1,1-tri-chloroethane. Mixtures thereof can also be employed. The
aqueous polymerization reaction is preferably conducted using
water-soluble initiators, buffers such as inorganic phosphates or
carbonates to maintain required pH level, and emulsifiers such as
salts of perfluoroalkyl carbonates or sulfonates.
[0050] In operation, preferably at least 10 wt % of the reactants
are converted to the product. More preferably, up to at least 80 wt
% of the reactants are converted to the product, and most
preferably, at least 90 wt % of the reactants are converted to the
product.
[0051] Operation of the process of the present invention under high
conversion conditions is generally preferred, particularly under
batch or solution, emulsion or suspension conditions. However, for
continuous, vapor phase, or fixed bed reactions, the present
process provides the unique advantage of recycling of the unreacted
starting materials thereby providing a cost advantage over other
known processes of the prior art.
[0052] Polymerization can be carried out essentially the same way
as the methods known and described in the art, such as, the methods
described in J. Polymer Sci. A: Polym. Chem. (1997) 35, 1593-1604,
and in U.S. Pat. Nos. 2,970,988; 3,893,987 (see Example 2); U.S.
Pat. No. 3,240,757; 5,292,816; 3,053,818 (see Example 6); U.S. Pat.
No. 3,812,066; 2,599,640; 6,342,569; 5,200,480; and 2,919,263.
[0053] Thus, the fluoroolefins can be readily polymerized to form
homopolymers under standard polymerization conditions known to a
person skilled in the art.
[0054] Alternatively, the fluoroolefin monomers can be also readily
polymerized to copolymers and terpolymers if one or more
ethylenically unsaturated comonomer is present.
[0055] Thus, a variety of polymers, such as, homopolymers,
copolymers, and terpolymers can be prepared by the process of the
present invention.
[0056] Accordingly, the present invention also provides polymer
blends comprising at least two polymers selected from homopolymers,
copolymers, and terpolymers prepared by the process of the present
invention.
[0057] Depending on the nature of the fluoroolefins and the
ethylenically unsaturated comonomers, the composistion of the
copolymers and terpolymers, the polymerization conditions, and the
molecular weights, the polymers can be obtained as colorless
liquids or transparent or white powders.
[0058] The polymers, copolymers and terpolymers according to the
present invention are useful in a variety of applications,
including preparation of barrier materials and coatings.
[0059] The process can further include purifying the reaction
product by precipitation or chromatography to obtain the product in
substantially pure form.
[0060] The following non-limiting examples are illustrative of the
various embodiments of the present invention. It is within the
ability of a person of ordinary skill in the art to select other
variable from amongst the many known in the art without departing
from the scope of the present invention. Accordingly, these
examples shall serve to further illustrate the present invention,
not to limit them.
Experimental Details:
[0061] Unless otherwise indicated, all parts and percentages are on
a weight basis.
EXAMPLE
[0062] An azeotrope of CTFE and 1234yf monomer combination. A
typical polymerization is run in a stirred, stainless steel
autoclave in which reactants are added by methods known in the art.
To a 300 mL autoclave is added (NH.sub.4).sub.2S.sub.2O.sub.8
ammonium persulfate: 15 mL of a solution of 0.56 g dissolved in 40
mL of de-O.sub.2/DI water. Na.sub.2S.sub.2O.sub.5 sodium
metasulfite: 19 mL of a solution of 1.2 g dissolved in 40 mL of
de-O.sub.2/DI water. [0063] FeSO.sub.4 ferrous sulfate: 0.005 g
dissolved buffer solution. [0064]
Na.sub.2HPO.sub.4/NaH.sub.2PO.sub.4 buffer: 1.34/0.68 g dissolved
180 mL. [0065] C.sub.7F.sub.15CO.sub.2(NH.sub.4) surfactant: 2.44 g
dissolved with buffer. [0066] Add 180 mL of the emulsion solution
(water/Na.sub.2HPO.sub.4/NaH.sub.2PO.sub.4/FeSO.sub.4/C.sub.7F.sub.15CO.s-
ub.2(NH.sub.4)).
[0067] The solution is stirred while 40.7 g as a mixture of 60 mol
% 1234yf and 40 mol % of CTFE are added in which an autogenous
pressure is obtained at 10.degree. C. The pressure is kept during
the polymerization as to obtain a constant concentration of
monomer. After 7 hours, the polymerization is stopped and monomers
are released from the autoclave. The polymerization suspension is
poured out and dried. 5.3 grams of a white copolymer was
obtained.
[0068] The polymerization any combination of monomers may be
combined in any combination to afford the properties suitable for
the intended application or applications. Those skilled in the art
may change the polymerization medium, catalyst, initiator system,
temperature, pressure, monomer mole ratio and concentration to
provide a suitable homopolymer, copolymer, terpolymer or
others.
[0069] The present invention has been described with particular
reference to the preferred embodiments. It should be understood
that variations and modifications thereof can be devised by those
skilled in the art without departing from the spirit and scope of
the present invention. Accordingly, the present invention embraces
all such alternatives, modifications and variations that fall
within the scope of the appended claims.
* * * * *