Constant rate cross-linked polymers

This approach was used to estimate the constants of conplex formation for CXi(2+) and Ni(2+), the conplexes incorporating with polyethylene (PE)-grafted - poly (acrylic) acid (12, 13). For cross-linked polymers K is one-two orders of magnitude hi er than that for soluble macroligands. However, the rate of metal complex formation is markedly lower than that of linear polymers and is controlled by the... 

As it is known [61], in case of different chemical reactions proceeding, including cross-linked polymers curing, an essential role is played by the so-called steric factor p (p < 1), showing that not all reacting molecules collisions occur with proper for chemical bond formation these molecules orientation. This factor importance in such treatment is defined by its proportionality to reaction rate constant k - the smaller p the smaller k and reaction proceeds with less rate. 

With difunctional cycloepoxides, the chain reaction develops in three dimensions to form a tightly cross-linked polymer. The rate of polymerization of the widely used aliphatic dicycloepoxide (Cyracure 6105 from Dow Chemicals) is still one order of magnirnde lower than that of diacrylate monomers, most probably because of a lower propagation rate constant. In this respect, the remarkable performance of cycloaliphatic epoxy-silicones should be mentioned, as these monomers were shown to polymerize... 

The first example for Method 2 was reported by Nishide and co-workers, who polymerised a metal complex of 1-vinylimidazole with l-vinyl-2-pyrollidone and divinylbenzene [8]. The metal-vinylimidazole complex was copolymerised, cross-linked with l-vinyl-2-pyrollidone by y-ray irradiation and the template metal ion was removed by treating the polymer complex with an acid. These poly(vinyl-imidazole) (PVI) resins adsorbed metal ions more effectively than the PVI resin prepared without the template. The number of adsorption sites and the stability constant of the Ni(II) complex were larger for the PVI resin prepared with the Ni(II) template, as seen by the smaller dissociation rate constant of Ni(II) from the resin. 

Curing formulation Polymer =100 HAF Carbon Black = 50 Naphthenic Oil = 5 ZnO = 5 S = 2 TMTD = 1 MBT = 0.5 Temp. = 145 °C. S. Table 1 ENB = 5-ethylidene-2-norbornene 1,4-HD = 1,4-hexadiene DCP = dicyclopentadiene MNB = 5-methylene-2-norbomene. Cross-linking reaction rate constant. 

The model compounds (III,a), (V,f), (VI,a) and NB described in Sect. B.lh) and the kinetic results obtained from the attack of t-butoxy radical on isooctane solutions of these products25, have been used to clarify some aspects of the mechanism of ter-polymer cross-linking. The reactivity of isooctane, expressed as the hydrogen abstraction reaction by t-butoxy radical relative to the j scission reaction of (CH3)3CO (see k2/kj values in Table 7), has been converted into the rate constant for the H abstraction from ethylene-propylene units (k5) by means of Pryor s... 

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