Graft copolymerization monomer concentration

Homopolymerization can also be reduced by working in the presence of large polymer concentrations, e.g. with polymers swollen in the monomer. In this case, even when the monomer B is sensitive to radiolysis the quantitity of homopolymer Bn remains unimportant. For example, Sebban-Danon(202) studied the effect of y-radiation on solutions of polyisobutylene in styrene. The much higher G-value of the polymer compared to that of styrene enhances the graft copolymerization with respect to the homopolymerization. 

The rate of dispersion (co)polymerization of PEO macromonomers passes through a maximum at a certain conversion. No constant rate interval was observed and it was attributed to the decreasing monomer concentration. At the beginning of polymerization, the abrupt increase in the rate was attributed to a certain compartmentalization of reaction loci, the diffusion controlled termination, gel effect, and pseudo-bulk kinetics. A dispersion copolymerization of PEO macromonomers in polar media is used to prepare monodisperse polymer particles in micron and submicron range as a result of the very short nucleation period, the high nucleation activity of macromonomer or its graft copolymer formed, and the location of surface active group of stabilizer at the particle surface (chemically bound at the particle surface). Under such conditions a small amount of stabilizer promotes the formation of stable and monodisperse polymer particles. 

In an apparently homogeneous solution, macromonomers, possibly together with the resulting graft copolymers, may lead to some structure formation such as micelle or looser association, which may in turn change the apparent reactivities due to some specific solvation or partition of the monomers around the active sites. Such a bootstrap effect [52] maybe responsible for some complicated dependency of the apparent reactivities on the monomer concentration and composition in radical copolymerization of 29 with n-butyl acrylate [53]. 

The results of the graft copolymerization on cellulose in various conditions are shown as a function of the irradiation time, initiator concentration, monomer concentration, presence of additive. 

Figure 8. Effect of monomer concentration on the graft copolymerization of methyl methacrylate onto cellulose nitrate with ceric ammonium nitrate as initiator. (Reprinted, with permission, from Ref. 19. Copyright 1979, Wiley.)...

Styrene is frequently used as part of some terpolymers with large practical utilization. One such copolymer is acrylonitrile-butadiene-styrene terpolymer (ABS). Usually it is made as poly(l-butenylene-graft-l-phenylethylene-co-cyanoethylene). This form of the copolymer can be made by grafting styrene and acrylonitrile directly on to the polybutadiene latex in a batch or continuous emulsion polymerization process. Grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of polybutadiene. The degree of grafting is a function of the 1,2-vinyl content of the polybutadiene, monomer concentration, extent of conversion, temperature and mercaptan concentration (used for crosslinking). The emulsion polymerization process involves two steps production of a rubber latex and subsequent polymerization of styrene and acrylonitrile in the presence of the rubber latex to produce an ABS latex. 

We achieved a systematic kinetic study of ABS. ABS resins, which are formed by copolymerization of styrene (S) and acrylonitrile (AN) in the presence of polybutadiene (PB), consist essentially of a mixture of SAN graft copolymer on PB and ungrafted SAN (styrene-co-acrylonitrile). The grafting kinetics and characteristics of the graft copolymer were studied in relation to the preferential solvation effects as functions of different variables type and concentration of PB, type and concentration of initiator, monomer concentration, conversion degree, etc. 

GRT particles have an ability to adsorb hydrocarbons. However, their adsorption capacity is low in comparison with adsorbent materials currently in use. To improve its adsorption capacity various methods for manufacturing of adsorbents and their various uses were proposed, as discussed in this section. An oil absorptive material of lower cost can be obtained by graft copolymerization through blending of various proportions of GRT of particle size of 100 mesh with 4-tert-butylstyrene (tBS), as a monomer in the presence of divinylbenzene, as a crosslinker, and benzoylperoxide, as an initiator (Wu and Zhou, 2009). Oil absorbency of the grafted blends reached a maximum of 24.0 g/g at a feed ratio GRT/tBS of 60/40 and a divinylbenzene concentration of 1 wt.%. 

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