Graft copolymerization polymerization

Issues to be considered in selecting the best stabilizing system are polymeric chain branching which increases with high temperature and the presence of some stabilizers, polydispersity of the particles produced, and grafting copolymerization, which may occur because of the reaction of vinyl acetate with emulsifiers such as poly(vinyl alcohol) (43,44). 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

In its simplest form the direct grafting method involves the irradiation of polymeric substrate in the absence or presence of oxygen. Graft copolymerization of the monomer to the polymer is then initiated through the free radicals generated in the latter. The reaction can be schematically written as ... 

The trapped radicals, most of which are presumably polymeric species, have been used to initiate graft copolymerization [127,128]. For this purpose, the irradiated polymer is brought into contact with a monomer that can diffuse into the polymer and thus reach the trapped radical sites. This reaction is assumed to lead almost exclusively to graft copolymer and to very little homopolymer since it can be conducted at low temperature, thus minimizing thermal initiation and chain transfer processes. Moreover, low-molecular weight radicals, which would initiate homopolymerization, are not expected to remain trapped at ordinary temperatures. Accordingly, irradiation at low temperatures increases the grafting yield [129]. 

In aqueous solutions the persulphate ion is known as a strong oxidizing agent, either alone or with activators. Thus, it has been extensively used as the initiator of vinyl polymerization [43-47]. However, only later, Kulkarni et al. [48] reported the graft copolymerization of AN onto cellulose using the Na2S203/K2S20s redox system. 

Bamford, Eastmond and coworkers have employed metal complexpolymeric halide redox systems to initiate block and graft copolymerization. The polymeric halides can be synthesized by a variety of techniques, including radical polymerization,281 anionic polymerization (Scheme 7.28),"so... 

Macromonomer RAFT polymerization is most effective with methacrylate monomers (Table 9.9).With monosubstituted monomers (e.g. S, acrylates) graft copolymerization, is a significant side reaction which can be mitigated but not eliminated by the use of higher reaction temperatures. 

Anionic polymerization of pivalolactone with the polystyrene anion produced only homopolymer mixtures, but the polystyrene carboxylate anion was able to give a block copolymer336. The block efficiency depends on catalyst ratio and conversion because the initiation step is slow compared with propagation337. Tough and elastic films were obtained by graft copolymerization or block copolymerization of pivalolactone onto elastomers containing tetrabutylammonium carboxylate groups338,339. ... 

Radiation-induced modification or processing of a polymer is a relatively sophisticated method than conventional thermal and chemical processes. The radiation-induced changes in polymer materials such as plastics or elastomers provide some desirable combinations of physical and chemical properties in the end product. Radiation can be applied to various industrial processes involving polymerization, cross-linking, graft copolymerization, curing of paints and coatings, etc. 

Dreyfuss, P., and Kennedy, J. P., Alkyl halides in conjunction with inorganic salt for the initiation of the polymerization and graft copolymerization of heterocycles, J. Polym. Sci.. Polym. Symp.. 56, 129-137, 1976. 

Photoinduced free radical graft copolymerization onto a polymer surface can be accomplished by several different techniques. The simplest method is to expose the polymer surface (P-RH) to UV light in the presence of a vinyl monomer (M). Alkyl radicals formed, e.g. due to main chain scission or other reactions at the polymer surface can then initiate graft polymerization by addition of monomer (Scheme 1). Homopolymer is also initiated (HRM-). 

Grading systems, for flax fiber, 77 617 Gradual failures, 26 981 Graduate students, role in facilitating research partnerships, 24 383 Graft copolymerization, 20 327. See also Graft polymerization Graft copolymers, 7 650-654 20 391 compatibilization efficiency of, 20 338 formation of, 23 395 in polymer blends, 20 324—325 in reactive compatibilization,... 

Grafting from method, 7 652-653 Grafting onto method, 7 654 Grafting process, 73 537 Grafting through method, 7 653 Graft polymerization. See also Graft copolymerization ABS, 7 419, 421 acrylic ester monomers, 7 386 of methacrylic ester polymers, 76 289-290... 

This problem has also been more durably addressed by modifying the surface properties of the polyolefin materials used to form polymeric sheets, by graft-copolymerizing to those surfaces a monomeric substance which, after copolymerization, confers hydrophilic properties and, in some cases, ion exchange properties. This technique has been found to be practical when the porous substrate is formed from PE, which has been found to lend itself well to a graft-copolymerization reaction of this kind. However, it has been found that when such a reaction is... 

Of particular interest are certain ionic graft copolymerizations in which the polymerization reaction is initiated only on the macromolecular framework and no homopolymer is formed. An example is provided by the formation of polymeric carbonium ions from chloride-containing polymers, such as poly(vi-nylchloride), in the presence of diethylaluminum chloride ... 

After 30-40 min the mixture warms up, indicating that the crosslinking graft copolymerization has begun.The sample gels and after 1 h has become almost solid, most of the styrene having polymerized. 

Fig. 11 Visualization of the sequential progress of branching stage by staining with rose bengal. DC-derivatized PST surface (GO) was graft-copolymerized with CMS and dimethylaminoethyl acrylamide (DMAEMA), and subsequent quarternization, while narrowing the irradiation area in each polymerization stage (item, GI item, GI+GII item, GI+GII- -GIII) by the combination of three kinds of masks with linear openings (line widths 2 mm for GI, 1 mm for GII, 0.5 mm for GUI). Bar=0.5 mm...

The same technique was applied to a mixture of polyethylene terephthalate and acrylic acid (34). The polymerizations were followed by looking at the acid number of the product the parameters studied were time, temperature, and monomer content see Fig.9a,b,c. The hydrophilicity, the solubility of the copolymer in benzyl alcohol, aniline, and a mixture of phenol and CHQ3 were increased by graft copolymerization. 

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