Natural rubber graft copolymers

Natural rubber, graft copolymers of natural rubber with acrylic or methacrylic acid esters of mono-functional CiC4 alcohols butadiene and isoprene polymers polymers... 

When the polymeric initiator contains many halogens, there will be many grafted side chains, and the product is called a comb or brush polymer. A variety of polymers can be used as the polymeric initiator, including polymers containing vinyl chloride and 4-chloromethylstyrene units, and halogenated natural and butyl rubbers. Graft copolymers are discussed further in Chaps. 5, 6, and 9. 

The properties of, say, natural rubber grafted with poly(methyl methacrylate) cannot be evaluated unless the copolymer is isolated from either homopolymer species. The methods used are based on fractional precipitation, selective solution, or a combination of these basic techniques. For details, refer to Chapter 3. In many cases, though, technologists are concerned with the materials as manufactured, so we consider in this context also the properties of the block and graft copolymers without homopolymer removed. 

When block and graft copolymers are dispersed in solvents, the solutions have properties that depend on whether or not the copolymer is eventually fully solvated. If the solvent is a good solvent for both sequences—for example, chloroform in the case of natural rubber graft copolymerized with poly(methyl methacrylate) (Halasa et al., 1976)—then both segment types are expanded and films cast from dilute solutions will usually be intermediate in properties to the... 

Compatibility and various other properties such as morphology, crystalline behavior, structure, mechanical properties of natural rubber-polyethylene blends were investigated by Qin et al. [39]. Polyethylene-b-polyiso-prene acts as a successful compatibilizer here. Mechanical properties of the blends were improved upon the addition of the block copolymer (Table 12). The copolymer locates at the interface, and, thus, reduces the interfacial tension that is reflected in the mechanical properties. As the amount of graft copolymer increases, tensile strength and elongation at break increase and reach a leveling off. 

ATBN - amine terminated nitrile rubber X - Flory Huggins interaction parameter CPE - carboxylated polyethylene d - width at half height of the copolymer profile given by Kuhn statistical segment length DMAE - dimethyl amino ethanol r - interfacial tension reduction d - particle size reduction DSC - differential scanning calorimetry EMA - ethylene methyl acrylate copolymer ENR - epoxidized natural rubber EOR - ethylene olefin rubber EPDM - ethylene propylene diene monomer EPM - ethylene propylene monomer rubber EPR - ethylene propylene rubber EPR-g-SA - succinic anhydride grafted ethylene propylene rubber... 

Mastication of natural rubber with elastomers which do not give gel allows the synthesis of soluble graft or block copolymers, depending on the tendency for chain rupture and transfer reactions. 

Natural Rubber and Synthetic Polyisoprene Polybutadiene and Its Copolymers Polyisobutylene and Its Copolymers Ethylene-Propylene Copolymers and Terpolymers Polychloroprene Silicone Elastomers Fluorocarbon Elastomers Fluorosilicone Elastomers Electron Beam Processing of Liquid Systems Grafting and Other Polymer Modifications... 

The polymerization of vinyl monomers in the presence of natural rubber, which is also an unsaturated polymer, has been examined initially by Le Bras and Compagnon (67, 740, 141). Jacobson (118) described graft copolymers of rubber latex with methyl methacrylate, styrene, acrylonitrile, etc. 

Grafting to rubber appears to be very strongly dependent on the nature of the initiator used for the polymerization of the monomer (767, 214). Recent experiments with wC-labeled initiators (6) demonstrate that very little graft copolymer was produced in the presence of 2,2 -azo-bis-iso-butyronitrile therefore almost all the grafting during reactions initiated... 

Similarly Cooper and Vaughan described high yields of graft copolymer, even at relatively high monomer concentration, in the system natural rubber-methyl methacrylate (70). It was found that nearly all... 

The mechanical degradation and production of macroradicals can also be performed by mastication of polymers brought into a rubbery state by admixture with monomer several monomer-polymer systems were examined (10, 11). This technique was for instance studied for the cold mastication of natural rubber or butadiene copolymers in the presence of a vinyl monomer (13, 31, 52). The polymerization of methyl methacrylate or styrene during the mastication of natural rubber has yielded copolymers which remain soluble up to complete polymerization vinyl acetate, which could not produce graft copolymers by the chain transfer technique, failed also in this mastication procedure. Block and graft copolymers were also prepared by cross-addition of the macroradicals generated by the cold milling and mastication of mixtures of various elastomers and polymers, such as natural rubber/polymethyl methacrylate (74), natural rubber/butadiene-styrene rubbers (76) and even phenol-formaldehyde resin/nitrile rubber (125). 

S. Miller and M. Fielden Graft copolymers from natural rubber... 

The separation and characterisation of graft copolymers from natural rubber. Riccrca Sci. 25, Suppl. 279 (1955). 

The first patent on HIPS, a blend of synthetic rubber and transparent polystyrene, was granted in Great Britain as early as 1912. The first graft copolymerization of styrene in the presence of rubber was carried out by Ostromislensky [5]. The decline in the demand for styrene monomer and styrene-butadiene rubber and the simultaneous availability of natural rubber on the world market in the late 1940s drove the development of styrene copolymer processes. 

Ceresa, R. J. "Synthesis and Characterization of Natural Rubber Block"and "Graft Copolymers in Block and Graft Copolymerization" Ceresa, R. J., Ed. John Wiley New York, 1973 Chap, 3. 

There have been many studies of graft copolymer formation initiated by ionizing radiation, and methods have been discussed.88 Among the systems studied are styrene onto polyethylene,88 styrene onto polypropylene,100 styrene onto Nylon-6,101 styrene onto ethylene-vinyl acetate copolymers,102 styrene and MMA onto natural rubber,103 pentafluorostyrene onto Nylon and polyethylene,104 acrylamide onto Nylon-6,105 acrylamide onto starch,100 vinyl monomers... 

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