addition polymerization


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addition polymerization

[ə¦dish·ən pə‚lim·ə·rə′zā·shən]
(organic chemistry)
A reaction initiated by an anion, cation, or radical in which a large number of monomer units are added rapidly (a chain reaction) until terminated by some mechanism, forming a high-molecular-weight polymer in a very short time; an example is the free-radical polymerization of propylene to polypropylene.
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The ratio of ([[[B.sub.H]].sub.0]/[[[B.sub.H]].sub.BTA/HQ,0]) represents the concentration correction factor, It should be noted that the value of[DELTA][H.sub.BTA/HQ.t] ([[[B.sub.H]].sub.0]/[[[B.sub.H]].sub.BTA/HQ,0]) used the computer simulation of the kinetics of the polymerization of BMI/ BTA in the presence of HQ may be overestimated (i.e., the conversion of the -C=c- associated with BMI may be underestimated) because of the competitive reaction of BMI with BTA via the Michael addition polymerization mechanism.
In this manner, the level of active hydrogen atoms of the two >NH groups and one >[CH.sub.2] group of BTA consumed by HQ was underestimated significantly during the Michael addition polymerization of BMI/BTA in the presence of HQ, as reflected in the quite high value of [theta] (= [[[B.sub.H]].sub.0]/[[M].sub.0] = 0.95) reported in Ref.
a kinetic model for the Michael addition polymerization of BMI/BTA in the presence of sufficient HQ (HQ/BTA = 1/1 (w/w)) to completely quench the free radical polymerization was developed, and the major governing equations (Eqs.
where [R.sub.M] is the total Michael addition polymerization rate, and the first and the second terms on the right hand are the Michael addition polymerization rates corresponding to the polymerizations of the -C=C- group of BMI with the >[CH.sub.2] group and the >NH group of BTA.
In an attempt to take into account the side reaction of BTA with HQ during the Michael addition polymerization of BMI with BTA in the presence of HQ, the following rate expression for the consumption of the active hydrogen atoms of the >[CH.sub.2] and >NH groups of BTA ([R.sub.BH]) was proposed in this study.
Development of Michael Addition Polymerization Kinetics Model
[R.sub.M,NH] and [R.sub.M.NH] represent the Michael addition polymerization rates corresponding to the polymerization of the -C=C-group of BMI with the >[CH.sub.2] group and the >NH group of BTA, respectively, and RM the total Michael addition polymerization rate.
The weight ratio of HQ/BTA equal to 1.0 was shown large enough to extinguish the free radical polymerization and, therefore, it was chosen for studying the BMI/BTA Michael addition polymerization kinetics hereinafter.
Under the circumstance, the crosslinking density and, consequently, the viscosity increase continuously with the progress of the Michael addition polymerization of the difunctional BMI with the tetrafunctional BTA.
7, A = 2053.5 L [mol.sup.l] [K.sup.l], [E.sub.a] = 36.1 kJ [mol.sup.1]) are the diffusion-controlled and the reaction-controlled Michael addition polymerization rate constants, respectively, C an adjustable constant that is the characteristic of the diffusion-controlled Michael addition polymerization, and [X.sub.M,c] the critical fractional conversion at which point the diffusion-controlled polymer reactions start to occur during the latter stage of polymerization.
Kinetic Scheme for the Free Radical Addition Polymerization Decomposition of peroxide I [[right arrow].sup.[k.sub.d]] x [R.sup.*] Initiation of monomers [R.sup.*] + M[[right arrow].sup.[k.sub.i]] [P.sup.*.sub.1] Propagation [P.sup.*.sub.n] + M[[right arrow].sup.[k.sub.p]] [P.sup.*.sub.n+1]) Termination (combination) [P.sup.*.sub.n] + [P.sup.*.sub.m] [[right arrow].sup.[k.sub.t,c]] [D.sub.n+m] (disproportionation) [P.sup.*.sub.n] + [P.sup.*.sub.m] [[right arrow].sup.[k.sub.t,d]] [D.sub.n] + [D.sub.m] where [k.sub.x] are the corresponding rate constants and depend on temperature according to the Arrhenius correlation: k = [A.sub.0] * [e.sup.-[E.sub.A]/R * T] [P.sub.n] denotes a growing copolymer (radical) of n monomer units.
It was also observed that the heating of MAF in THF at 70 [degrees] C does not induce addition polymerization of MAF.