Copolymer formation, graft

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... 

A similar procedure was described by Eboatu and Ferguson. An object of analysis was the complex obtained by template polymerization of acrylic acid in the presence of poly(vinyl pyrrolidone). The polycomplex was dispersed in dry benzene and treated with diazomethane. The insoluble portion was filtered. The filtrate containing poly(methyl acrylate) was concentrated and finally dried. The insoluble fraction was scrubbed with methanol to extract polyCvinyl pyrrolidone). The residue was further washed with methanol and then dried. These three portions were characterized by IR spectroscopy. It was found that only about 70% separation of the complex is achieved. The occurrence of inseparable portion is attributed to a graft copolymer formation. For the separated... 

In this paper, the surface grafting of rayon fabrics with nitrogen and phosphorus containing polymers in cold plasma is studied. The analytical data (IR spectroscopy, TGA, electron microscopy, elemental analysis, etc.) indicate the formation of grafted copolymers. The grafted rayon fabrics present improved flame-retardant properties, the best behavior was proved by those grafted with polyurea of phosphinic acid. 

Interchain copolymer formation Copolymers of reactive polystyrene and polymers with amide, mercaptan, epoxy, hydroxy, anhydride or carboxylic acid groups, copolymer of polypropylene grafted with maleic anhydride and nylon-6, copolymer of polyolefines and polystyrene, copolymer of EVA grafted with methacrylates and grafted polystyrene... 

Many authors elucidated functionalization of polymers containing reactive oxirane moieties. Epoxidized NR, BR, IR and/or the respective model hydrocarbons, poly (butadiene-co-isoprene, various epoxy resins, poly (2,3-epoxypro-pyl methacrylate) and its copolymers or grafted systems were mostly exploited. Stabilizers based on epoxidized unsaturated rubbers are of the top interest. The mechanism of the functionalization process was studied in details by means of 3,4-epoxy-4-methylheptane and 1,2-epoxy-3-ethyl-2-methylpentane as model compounds [289]. The ring opening of the asymmetric oxirane is regiospecific. Aliphatic primary amines attack the least substituted carbon atom and can be involved in crosslink formation. Aromatic primary and secondary amines are less reactive than aliphatic ones because of their lower basicity the attack on the least substituted carbon atom is however preferred too. 

Bulk polymerizations, such as addition (free-radical- and ionic-based) and step-growth types. Grafting polymerization by small molecules. Interchain copolymer formation, based on chain cleavage, graft copolymerization, and end-group block copolymerization. 

By a similar degradation and graft copolymer formation mechanism block copolymers could be obtained by reactive extrusion. A prerequisite is the presence of functional groups and the interaction of these groups with immiscible polymers during melt processing. Several polyamide block copolymers are synthesised by a melt-modification process. 

Graft copolymerization has some of the features of block-copolymer formation except that the radical centres are not at the end of the chain but in-chain. The polymer to which the graft is attached is the backbone polymer. Cowie (1989a) has recognized three different ways in which graft copolymers may be formed ... 

Although a radical catalyst is not necessary for graft polymerization when the alternating copolymer forms spontaneously, a radical catalyst is required when alternating copolymer formation requires radical initiation (10). 

Better control of grafting and less homopolymer formation is achievable in ionic reactions than can be obtained in free-radical reactions. Anionic grafting via backbone initiation has been demonstrated (22) with caprolacteim on macromolecular ester sites of styrene/methyl methacrylate copolymers. Cationic grafting of isobutylene onto poly(vinyl chloride) with the aid of aluminum alkyl has been carried out by J. P. Kennedy (23). 

On the basis of these observations, block copolymer formation was claimed. It was reported, however, that some grafting also occurs when DXL is polymerized in the presence of preformed polypMOSt. Thus, when dead polypMOSt was added to the solution of living polyDXL, up to 70% of polyDXL was grafted by aromatic alkylation onto polypMOSt ... 

When it is desired to form a graft, block, or crosslinked copolymer, there are two distinct processes available for copolymer formation ... 

Graft copolymer formation between two polymers, each with different functionality, may occur either by direct reaction (e.g., A-acid end-group + B-pendent epoxy group), or by addition of a condensing agent that activates functionality of one polymer for reaction with functionality of the second polymer (e.g., A-acid + B-alcohol + triaryl phosphite). 

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