Grafting-polymerization reactions

As with the difunctional cross-linking reactions, very little research has been done with grafting-polymerization reactions. None of the research done was directed toward archaeological wood restoration. 

Parquet P, Kunze A, Padeste C, Solak HH, Guersel SA, Scherer GG, et al. Influence of the solvent viscosity on surface graft-polymerization reactions. Polymer 2007 48(17) 4936—42. 

The reaction of fiber with an epoxide leads to the formation of an ether linkage and a new OH group. Therefore graft-polymerization reactions are possible [38]... 

Thus, if the tremendous applications potential of these cellulose-synthetic poljnner composites is to be realized, new and better processes for the graft polymerization reaction onto cellulosics are needed. The new processes should provide for ... 

More detailed work is needed to thoroughly study this graft polymerization reaction and to completely characterize the graft polymers produced. 

Hydrophilic modification of the PTFE membranes is performed for treatment of potable water and waste water. Xu et al. reported the graft copolymerization of AAc and NaSS binary monomers from the high energy EB pre-irradiated PTFE microporous membrane [137]. The AAc/NaSS binary monomers exhibited synergistic effect and improved the graft polymerization reaction with the pre-irradiated PTFE membrane. The water flux decreased with the increase in NaSS concentration. The grafted polymer brushes on the PTFE membrane decreased the water contact angle and produced a stable hydrophilic surface. 

This may relate to the oxidizing effect of sulfuric acid on the poly-hydric alcohol structure of lignin and its transformation into the quinonoid form. Oxidation of the polyhydric alcohol of lignin into quinone has been achieved on using ceric ammonium sulfate which inhibited graft polymerization reactions on using this initiator. ... 

RADICAL-INITIATED GRAFT POLYMERIZATION Reaction Parameters... 

Graft polymerization can be accomplished provided that active sites are available on the surface for reaction with monomers. Two fundamental methods of creating... 

Very thin films may be also obtained through adsorption of a thin layer from solution [11,71,74] or chemical grafting [98] which is achieved by a polymerization reaction at the surface. A polymer film may also be deposited on the surface by plasma polymerization [99]. It is then, however, usually crosslinked and chemically not well-defined. 

The theory of radiation-induced grafting has received extensive treatment [21,131,132]. The typical steps involved in free-radical polymerization are also applicable to graft polymerization including initiation, propagation, and chain transfer [133]. However, the complicating role of diffusion prevents any simple correlation of individual rate constants to the overall reaction rates. Changes in temperamre, for example, increase the rate of monomer diffusion and monomer... 

The presence of methylenic bands shifted at higher frequency in the very early stages of the polymerization reaction has also been reported by Nishimura and Thomas [114]. A few years later, Spoto et al. [30,77] reported an ethylene polymerization study on a Cr/silicalite, the aluminum-free ZSM-5 molecular sieve. This system is characterized by localized nests of hydroxyls [26,27,115], which can act as grafting centers for chromium ions, thus showing a definite propensity for the formation of mononuclear chromium species. In these samples two types of chromium are present those located in the internal nests and those located on the external surface. Besides the doublet at 2920-2850 cm two additional broad bands at 2931 and 2860 cm are observed. Even in this favorable case no evidence of CH3 groups was obtained [30,77]. The first doublet is assigned to the CH2 stretching mode of the chains formed on the external surface of the zeolite. The bands at 2931 and... 

Two different emulsion polymerization reactions were Investigated. One was the polymerization of acrylonitrile and methylacrylate (75/25 AN/MA) In the presence of an acrylonitrile elastomer (70/30 BD/AN) to produce a graft resin, llie second was the copolymerization oiE acrylonitrile and styrene (70/30 AN/S). Chromatographic analyses of latex solutions were conducted periodically during both types of polymerization reactions, using acetonitrile as latex solvent and chromatographic mobile phase. 

In summary, these exploratory data suggest that the chromatographic method used could be a valuable tool for study of this polymerization reaction. Reasonable data were obtained for amount and composition of the copolymer. Formation of graft polymer and/or nitrile rich polymer was detected. More detailed chromatographic study of this batch polymerization could lead to a practical on-line monitoring method... 

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-). 

Strongly anionic, highly water-soluble, graft copolymers of starch can be made by adding 2-propenamide and sodium 2,2-dimethyl-3-imino-4-oxohex-5-ene-1-sulfonate (Na DMIH) to the polymerization reactions. See references 43 and 56 for a discussion of these polymers. 

Polymerization reactions. Polymerization of ethylene to polyethylene has been conducted at pilot-plant scales reaching a target of 1500 tons per year. Some reactions, including polymerization and copolymerization of polymers for grafting on textile fibers, have been successfully performed. Similarly, cross-linking of polyethylene to improve thermal properties has also been achieved. 

The presence of lignin, resins or other extractives in the fibers may interfere with the initiation or polymerization reactions, e.g. by termination or chain transfer of free radical reactions from phenolic groups. In some cases, lignin has no adverse effect and may even be grafted . 

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