Comonomers structure

Fig. 3. Effect of comonomer structure on the glass-transition temperature of VDC copolymers (72), where A represents acrylonitrile B, methyl acrylate ...

When PCS and PBS are cocrystallized with PTS two sorts of mixed crystals are formed simultaneously, i.e. active crystals in which up to 20 percent of PCS can be incorporated in the PTS lattice and inactive crystals where PTS is dissolved in the comonomer structure. The cocrystallization diagram for the system PTS-PCS is shown in Fig. 33. 

Type Comonomer Structure Prevalent opening of trienic system Structure of the repeat unit Copolymer properties ... 

XR (sulfonate) comonomer structures Nafion, Flemion CF2=CF0CF2CF(CF3)0CF2CF2S02F... 

Incorporation of comonomer units into the polyoxymethylene chain leads to a considerable decrease of the melting temperature 139). The effect of comonomer structure and concentration on the melting temperature is shown in Table 7.18. 

No Comonomer structures Reaction conditions Copolymer structures and properties Ref. 

FIGURE 21.24 Typical functional comonomer structures for each ionomer system. (Reproduced from Doyle, M. and Rajendran, G., in Handbook of Fuel Cells Fundamentals, Technology and Applications, Vielstich, W, Gasteiger, H.A., and Lamm, A., eds., Vol. 3, John Wiley Sons, Chichester, U.K., 2003. With permission.)... 

Comonomer structure, content, and distribution 4. Enzymes (kinds and concentrations)... 

Wulff, G. Dhal, P.K. Chirality of polyvinyl compounds. 6. Unusual influences of the comonomer structures on the chiroptical properties of optically active vinyl copolymers... 

At the first-order level, the preference of the metallocene for one monomer over the other is quantified by the two reactivity ratios, r (= knlkn) and r2 (= 22/ 21)- Since ethylene is invariably more reactive than any other monomer, ri > 1 and T2 < 1. Study of the First-Order Markov constants (Table 2) reveals important correlations with metallocene and comonomer structure. As is to be expected, the larger the comonomer, the higher the r value, indicating a steric hindrance to its insertion. Bridged metallocenes, such as structure 2, give catalysts with much lower ri values than do unbridged metallocenes. In general, metallocenes copolymerize monomers with a tendency toward alternation of monomers, as indicated by a value for r r2 less than 1. 

PE is a crystallisable polymer. Since chains may be entangled or otherwise imperfect (branching, comonomers, structural defects, etc.), the structure is not completely regnlar, and hence PE is best described as a semi-crystalline polymer. Many of the properties of PE and most of its properties... 

This cooperative effect, depending on comonomer structure and polymer stereoregularity, can be transmitted for long chain sections, a small amount of chiral comonomer being sufficient to induce chirality of one single type in the whole macromolecule. This effect can be of great interest for the simple and economical synthesis from commercial achiral monomers and a small amount of chiral comonomers of functional optically active copolymers with an ordered chiral secondary structure to be used as reagents or catalysts for asymmetric synthesis. 

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