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Polymerization activation

Complexation of the initiator and/or modification with cocatalysts or activators affords greater polymerization activity (11). Many of the patented processes for commercially available polymers such as poly(MVE) employ BE etherate (12), although vinyl ethers can be polymerized with a variety of acidic compounds, even those unable to initiate other cationic polymerizations of less reactive monomers such as isobutene. Examples are protonic acids (13), Ziegler-Natta catalysts (14), and actinic radiation (15,16). [Pg.514]

In our laboratory, Sun et al. [35] reported that the terahydrofuran hydroperoxide (THFHP)-DMT system could initiate vinyl polymerization actively with very low Ea as 35.2 kJ/mol for MMA and 34.3 kj/mol for AAM polymerization. [Pg.231]

Nylon 4 is produced hy ring opening 2-pyrrolidone. Anionic polymerization is used to polymerize the lactam. Cocatalysts are used to increase the yield of the polymer. Carhon dioxide is reported to he an excellent polymerization activator. [Pg.366]

Recently samples of TiCl2j active in polymerization without additional activation, were prepared (156-159). The activity of TiClj in ethylene polymerization was practically the same as the activity of a conventional two-component system TiClg + AlEtjCl (see Fig. 3). The polymerization activity of TiClj depends to a large extent on the parameters tempera-... [Pg.193]

The value of Kp as a measure of the reactivity of the active centers in the propagation reaction is the most fundamental characteristic of polymerization catalysts. The conclusions on the polymerization mechanism based on the correct values of N and Kp are much more unambiguous than those made when considering only the data on the polymerization activity and molecular weight of a polymer. [Pg.195]

Our attempts to prepare chromium hydrides and to evaluate their role in polymerization catalysis eventually led to the isolation of a series of alkyls and hydrides lacking any ancillary ligands besides the cyclopentadienyl moiety (see below).[6] Reduced to the essence of alkyls, these complexes provided another piece of evidence in the growing case against polymerization activity of divalent chromium none of the alkyls even reacted with ethylene. The hydride underwent one insertion and stopped at the stage of an ethyl group. [Pg.154]

While we have now found many well-characterized Cr I alkyls which catalyze the rapid polymerization of ethylene under very mild conditions, none of the various CrU alkyls we have prepared have shown any indication of polymerization activity. Those who would continue to invoke Cr as an "active oxidation state" for ethylene polymerization should be called upon to provide experimental support for that proposal. [Pg.155]

The initiation step of chain growth creates a reactive site that can react with other monomers, starting the polymerization process. Before the monomer forms the reactive site, the initiator ( ) (which maybe either a radical generator or an ionic species) first creates the polymerization activator (A) at a rate defined by the rate constant kv This process can be represented as shown in Eq. 4.7. [Pg.89]

DNA polymerase I is a nonessential enzyme, since viable E. coli mutants lack it (pol A). This conclusion is complicated, however, since the enzyme catalyzes three separate chemical reactions. It polymerizes deoxyribonucleoside triphosphates, and it has two exonucleolytic activities, a 3 to 5 activity and a 5 to 3 activity. The pol A - mutants lack only the polymerization activity. Other mutants lacking both the polymerase and the 5 to 3 exonuclease activity are lethal. Thus the exonuclease function is the more important one. This fits with the role of this enzyme in removing damaged DNA segments (DNA repair) and in removing covalently attached RNA from DNA chains. We will later see that small RNAs serve as primers of DNA synthesis. [Pg.225]

Metal allyls that were found not to have any polymerization activity at all, despite extreme care in preparation and polymerization, wereNi(allyl)s, Pd(allyl)2, and Mn(aHyl)s (9) and these are probably not polymerization... [Pg.267]

III. Ligand Replacement in Transition Metal Alkyl Compounds and Polymerization Activity... [Pg.288]

Zirconium bis(amides) such as (35) and (36) display moderate ethylene polymerization activities.133,134 Complex (37) containing a chelating diamide ligand has been shown to initiate the living polymerization of a-olefins such as 1-hexene (Mw/Mn= 1.05-1.08) with activities up to 750gmmol-1 h-1.135-137 The living polymerization of propylene using this system activated with... [Pg.7]

The highest ethylene polymerization activity for a tetradentate salen-type group 4 complex was reported for silica supported (64) (600gmmol-1h bar ).193 Activities for a range of related zirconium and titanium complexes such as (65)-(67) are typically an order of magnitude lower.194-196... [Pg.10]

The complexation of a range of tridentate monoanionic ligands has been examined across the transition metal series and (98) was shown to catalyze the polymerization of ethylene with an activity of 500 gmmol-1 h-1 bar-1.264 Bis(iminopyrrolide) complexes, such as (99),265 display moderate ethylene polymerization activities (70 gmmol-1 h-1 bar-1), as does the /3-diketiminate complex (100).2 6... [Pg.13]


See other pages where Polymerization activation is mentioned: [Pg.140]    [Pg.461]    [Pg.4]    [Pg.187]    [Pg.253]    [Pg.855]    [Pg.374]    [Pg.21]    [Pg.251]    [Pg.115]    [Pg.263]    [Pg.298]    [Pg.158]    [Pg.158]    [Pg.160]    [Pg.202]    [Pg.3]    [Pg.3]    [Pg.9]    [Pg.13]    [Pg.17]    [Pg.14]    [Pg.15]    [Pg.79]    [Pg.90]    [Pg.91]    [Pg.91]    [Pg.92]   
See also in sourсe #XX -- [ Pg.539 ]




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1.5- cyclooctadiene polymerization activity

Activated monomer enzymatic polymerization

Activated polymerization

Activated polymerization

Activation Energies of Propagation and Termination in Free Radical Polymerization

Activation energies anionic polymerizations

Activation energies cationic polymerizations

Activation energies step-growth polymerizations

Activation energies, step polymerization

Activation energy Ziegler—Natta polymerization

Activation energy anionic chain polymerization

Activation energy cationic chain polymerization

Activation energy emulsion polymerization

Activation energy olefin polymerization

Activation energy polymerization

Activation energy radical chain polymerization

Activation energy ring-opening polymerization

Activation energy stereoselective polymerization

Activation parameters polymerization

Activation temperature polymerization activity

Activation temperature polymerization kinetics

Activation volume selected polymerization reactions

Activator polymerization

Activator polymerization

Activators of anionic polymerization

Active Ester-Forming Polymeric Reagents

Active Species in the Polymerization of Cyclic Acetals

Active centres of polymerizations

Active centres of radical polymerizations

Active esters polymeric

Active in polymerizations

Active polymerization systems

Anionic chain polymerization activation parameters

Anionic polymerization active species

Anionic ring opening polymerization activators

Atom transfer radical polymerization activation rate constants

Atom transfer radical polymerization active copper complexes

Biologically Active Polymeric Displays

Biosynthesis of Monosaccharide Components, and Their Activation for Polymeric-Chain Formation

Catalytic activity, enzymes enzymatic polymerization reaction

Cationic coordination polymerization activated monomer

Cationic polymerization active species

Cationic polymerization covalent active species

Chain-growth polymerization laboratory activity

Cyclic acetal polymerization active sites

Discovery of Highly Active Molecular Catalysts for Ethylene Polymerization

Ethylene Polymerization Activity of Zr- and Ti-FI Catalysts

Ethylene polymerization active site concentration

Ethylene polymerization, with Lewis acid catalytic activity

Ethylene polymerizations, highly active

Ethylene polymerizations, highly active living

Ethylene polymerizations, highly active molecular catalysts

Exchange Activity (Immortal Polymerization)

Free radical addition polymerization activation energies

Free radical polymerization activation energies

Free radical polymerization biologically active polymers

Highly Active Ethene Polymerization Catalysts with Unusual Imine Ligands

Initiation of Polymerization at the Active Center

Isoprene polymerization active site distributions over kinetic

Lactams polymerization, activated monomer

Lactams polymerization, activated monomer mechanism

Living radical polymerization activation-deactivation processes

Living radical polymerization activator

Living radical polymerization active species

Monomers, optically active polymerization

Of anionic activated polymerization

Optically active hydrocarbons polymerizations

Organochromium catalysts polymerization activity

Oxirane polymerization active groups

Oxirane polymerization active sites

POLYMERIC SURFACE ACTIVE

POLYMERIC SURFACE ACTIVE AGENT

Plasma polymerization, electrically active

Plasma polymerization, electrically active polymers

Polymeric activated dextrans

Polymeric adsorbents versus activated carbons

Polymeric materials/polymers electrically active

Polymerization actinically activated

Polymerization activated monomer mechanism

Polymerization activators for

Polymerization active center

Polymerization active life

Polymerization activity

Polymerization activity

Polymerization activity cyclopentene

Polymerization by activated monomer mechanism

Polymerization monomer activation

Polymerization on activated ligands

Polymerization reversible activation

Polymerization surface activation

Polymerization with Two Active Species

Polymerization with activated monomer

Polymerization without Transfer and with One Active Species

Polymerization, activation anionic

Polymerization, activation cationic

Polymerization, activation coordination

Polymerization, activation deactivation

Polymerization, activation degree

Polymerization, activation equilibrium

Polymerization, activation experiments

Polymerization, activation industrial

Polymerization, activation ionic

Polymerization, activation kinetics

Polymerization, activation living

Polymerization, activation mechanisms

Polymerization, activation pressure effects

Polymerization, activation radiation induced

Polymerization, activation radical

Polymerization, activation regulated

Polymerization, activation ring-opening

Polymerization, activation solvent effects

Polymerization, activation spontaneous

Polymerization, activation statistics

Polymerization, activation structure-controlled

Polymerization, activation thermal

Polymerizations initiated by thermally activated donor-acceptor complexes

Propylene polymerization zirconocene precatalysts activated with

Radiation-activated polymerization

Radical chain polymerization activation parameters

Radical polymerization activation rate constants

Replacement in Transition Metal Alkyl Compounds and Polymerization Activity

Ring-opening polymerization activated monomer

Silica-alumina catalysts, active sites ethylene polymerization

Ziegler-Natta olefin polymerization active cationic species

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