Graft copolymers mercaptans

Free radical polymerization of styrene, of acrylate and of methacrylate monomers in solutions at 60° C in the presence of this preformed polymer produced graft copolymers in high efficiency, the chain transfer constants for these mercapto groups with styrene and methyl methacrylate being similar to those found with simple mercaptans (80, 85). 

A quantitative method has been developed to separate free and graft copolymers in an ABS sample. The ABS powder is dispersed in MEK and then introduced into the cells of a preparative ultracentrifuge. After the reproducibility of the procedure was ascertained, the method was used to determine the grafting parameters of samples polymerized under specific conditions. This analytical technique is well suited to demonstrate how the grafting efficiency or grafting density is influenced by various polymerization conditions such as mercaptan content, monomer flow rate, emulsifier content, or polybutadiene content. The effects of other variables such as temperature, the initiator system, and characteristics of the polybutadiene latex can also be demonstrated. 

Another example is formation of mercaptan groups on cellulose in order to form graft copolymers ... 

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... 

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. 

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