Divinylbenzene effect, styrene grafting

Figure 1. Role of dose rate in the synergistic effect of divinyl-benzene and sulfuric acid on grafting of styrene on polypropylene film in methanol dose rate of 4.1 x 104rad/hr to total dose of 2.4 x lO rad (A) styrene-methanol, (o) styrene-sulfuric acid (0.2M). ( ) styrene-methanol-divinylbenzene (1% v/v), and (o) styrene-methanol -di vinyl benzene (1% v/v)-sulfuric acid (0.2M). dose...

New polymeric solid supports have been devised, which include macroporous styrene-divinylbenzene containing large fixed pores, porous glass beads, insoluble carbohydrate polymers, poly(ethylene oxide), cross-linked derivatives of polyacrylamide resins, and graft copolymers of polystyrene and poly(ethylene oxide). The last two have been the most effective and widely used and have competed well with the original copoly(styrene-divi-nylbenzene) beads. 

In preliminary work (19), divinylbenzene (DVB) has been reported to be a useful additive for enhancing the above grafting reactions. These early data (19) indicate that there are possible common mechanistic pathways between the acid effect and the DVB process. More detailed DVB studies are discussed in this paper for enhancing the radiation grafting yields of styrene in methanol to films of polyethylene and polypropylene. The work has been extended to include the use of other polyfunctional monomers such as tri-methylol propane triacrylate (TMPTA) as additives. The possibility of being able to use these additives for copolymerisation of monomers to naturally occurring trunk polymers such as cellulose will also be considered. 

Figure 1. Effect of divinylbenzene on grafting of styrene to polyethylene film in methanol at dose rate of 4,1 X rad/h to total dose of 2,5 X 10 rad. Key O, styrene-methanol , styrene-methanol-divinylbenzene (1% v/v).

The inclusion of divinylbenzene (DVB) enhances the radiation grafting of styrene in methanol to polypropylene (Figure 7) especially at concentrations above 30% monomer where there is generally a 100% increase in yield. Compared with acid and neutral solutions, the Trommsdorff peak in the DVB solution has moved slightly to higher monomer concentration for polypropylene grafting. The acid enhancement is greater than the DVB effect at monomer concentrations lower than 30%, but the reverse holds above this styrene level with polypropylene. 

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