Primary chain, length

One of the calculation results for the bulk copolyroerization of methyl methacrylate and ethylene glycol dimethacrylate at 70 C is shown in Figure 4. Parameters used for these calculations are shown in Table 1. An empirical correlation of kinetic parameters which accounts for diffusion controlled reactions was estimated from the time-conversion curve which is shown in Figure 5. This kind of correlation is necessary even when one uses statistical methods after Flory and others in order to evaluate the primary chain length drift. 

If the degree of cross-linking p is small (and the primary chain length therefore great), 0 =tf s, giving... 

Chain scission will have the effect of decreasing the primary chain length, which, of course, is a highly important factor in respect to the vulcanizate network structure. 

Table I. Influence of Primary Chain length on PC Formation...

Compartmentalization of radicals into polymer particles may yield a unique MWD for the linear chains, as discussed in Sect. 3.1, except when the dominant chain termination mode is the chain transfer reaction. Branched polymer molecules are assemblies of linear polymer chains (called primary chains), and compartmentalization effects on the primary chain length distribution must be properly accounted for. 

As can be seen in Fig. 1, no gel effect was observed even beyond the gel point in contrast to the polymerization of common multivinyl compounds such as EDMA [6]. This unusual polymerization behavior is characteristic of allyl polymerization, in which monomer chain transfer is essentially a termination reaction [42] in contrast to bimolecular termination of growing polymer radicals in common vinyl polymerization. In other words, primary chain length is quite short and kept nearly constant during polymerization as is required for the application of Eq. (4). 

Table 1 shows the experimental results of DAP, including the residual unsaturation and the number-average degree of polymerization P of DAP pre-polymer and the primary chain length Pn(ch)- In Table 2 the results of Rus,o, Pn,o. and Pn(ch),o as extrapolated to zero conversion from the conversion-dependences based on the data of Table 1 are summarized along with those of DAI and DAT polymerizations. 

Primary chain length expressed as the number of reacted allyl units per chain, corresponding to the degree of polymerization of polyfallyl acetate) obtained after saponification and reesterification of DAP prepolymer. 

Soper et al. have investigated the copolymerization of St with DVB [21] the intrinsic viscosity [ii] of the resulting polymer was measured in order to explore the occurrence of intramolecular cyclization leading to the formation of loop structure and thus, resulting in the reduced [r ] of the polymer. As a matter of course, this intramolecular cyclization is influenced by the flexibility of the polymer chain, the content of pendant double bonds, and the primary chain length. 

Both models were simulated with the same crosslinked configurations. In both cases the relaxation of the systems was extremely slow. Considering tat w 180r for N — (Ns) and 3700r for N= 50 the primary chain length, it was observed that the characteristic relaxation time increased by about a factor of 10 compared to rj r=5o or more than 100 compared to the Rouse time of the average inner strand for the LJ case. The soft potential model displayed an even slower relaxation. 

Saka, Y, Zetterlrmd, P.B., Okubo, M. Gel formation tmd primary chain lengths in nitroxide-mediated radical copolymerization of styrene and divinylbenzene in miniemulsion. Polymer 48(5), 1229 1236 (2007)... 

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