Methyl methacrylate-grafted rubber latex

Methyl methacrylate-grafted latex rubber particles has been studied for the impact toughening of PS styrenic matrix polymers. The... 

Since these rubber particles are highly filled with a homopolymer or a copolymer, the rubber is already reinforced with a resin to give a higher modulus particle than the grafted rubber latex. On the basis of the uniqueness of these rubber particles, this process is also more appropriate in manufacturing high-strength medium-impact ABS polymer (31), or rubber-reinforced styrene-methyl methacrylate copolymer (32). The... 

Poly(methyl methacrylate) grafted on the backbone of natural rubber latex... 

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. 

Most ABS is made by emulsion polymerization. A polybutadiene or nitrile rubber latex is prepared, and styrene plus acrylonitrile are grafted upon the elastomer in emulsion. The effect of rubber particle size in ABS graft copolymer on physical properties is the subject Chapter 22 by C. F. Parsons and E. L. Suck. Methyl methacrylate was substituted for acrylonitrile in ABS by R. D. Deanin and co-workers. They found a better thermoprocessability, lighter color, and better ultraviolet light stability. 

We used a matrix copolymer system consisting of methyl methacrylate (MMA) and styrene (St) grafted on polybutadiene rubber. The variables investigated were latex particle size (360, 2000, and 5000 A), degree of grafting, rubber content, and the degree of particle dispersion. The following variables must be considered when a transparent impact polymer is prepared. 

Clarity of Graft Polymers with Varying Methyl Methacrylate/ Styrene Ratios. Refractive index considerations 7,8) and general state of the art considerations (8) favor methyl methacrylate (MMA) over styrene (St) as the major monomer portion of the matrix. With this in mind, we selected MMA/St ratios from 62/38 to 80/20 (wt %). Using a commercial Firestone butadiene latex (2004) to supply the 15% rubber graft, polymerization runs were made as outlined in Table I. 

Material. Optically clear films (about 5 mils thick) of three SA (saturated acrylic) plastics (3) that contained 25, 33, and 50% of an acrylic graft rubber (referred to as SA-1, SA-2, and SA-3) were compression molded. The acrylic graft rubber latices were latex blended with a resin latex composed primarily of methyl methacrylate, and the blend was coagulated. The compositions of these three polymers are as follows SA-1, 79/17/4 wt %—methyl methacrylate/butyl acrylate/styrene SA-2, 72/23/5 wt %—methyl methacrylate/butyl acrylate/styrene SA-3, 59/34/7 wt %—methyl methacrylate/butyl acrylate/styrene. All three graft rubbers contained low levels of a crosslinking comonomer (less than 1.0 wt %). 

Cooper and co-workers 16> made a comparative study of the grafting of methyl methacrylate upon natural rubber latex using visible, ultraviolet and y-radiations as energy sources. It was found that the grafting took place with equal efficiency whether the radiation source was light or y-rays. 

When chloroprene was grafted onto cationic aminated starch, a latex was obtained that imparted wet strength to paper and also served as a pressureless adhesive for wood 2951 Starch dialdehyde when grafted with acrylonitrile, methyl methacrylate, or both, produced a biodegradable filler for poly (vinyl chloride) plastics.2942 Starch xanthates grafted with vinyl monomers were also used to produce additives for reinforced foamed rubber.2944,2945... 

Cockbain, E.G., Pendle, T.D., Turner, D.T., 1959. Formation of graft polymers by gamma-irradiation of natural rubber latex and methyl methacrylate. J. Polym. Sci. 39 (135), 419 26. 

These groups can then be used to initiate grafting by any of the methods already discussed. Latex phase grafting is generally favored for its simplicity natural rubber grafts with methyl methacrylate styrene, acrylonitrile, and vinyl chloride have been made in this way (Cockbain et al., 1959). 

Copolymer composition has a direct effect on the Tg of the polymer, which determines the minimum film forming temperature (MFFT) of the latex and the application. Thus, a 95/5 wt/wt butyl acrylate/methyl methacrylate is an adhesive, whereas a 50/50 copolymer of the same monomers is a binder for paints. Copolymer composition affects properties such as resistance to hydrolysis [4] and weatherability. In situ formed blends of random copolymers of different compositions may be beneficial for application properties [5]. Conventional free-radical polymerization, which is the process used to manufacture almost all commercial emulsion polymers, does not allow the production of block and gradient copolymers (accessible by means of controlled radical polymerization [6], Section 3.3). Nevertheless, graft copolymers are frequently formed, and the extension of grafting largely determines the application properties. Thus, grafting determines the size of the rubber domains in ABS polymers, and the toughness of these polymers increases with rubber size. 

This type of graft copolymerization has been applied to the grafting of monomers like styrene and methyl methacrylate to natural rubber [271], directly in the latex [272,273]. Similar methods have been developed for grafting the foregoing monomers, and many other vinyl monomers, to synthetic rubbers like SBR, leading to a variety of plastic-reinforced elastomers and rubber-reinforced high-impact plastics [270,274]. In this case, grafting can also occur by the copolymerization of the monomer with the unsaturated bonds (mainly vinyl) in the polymer as described previously [see Eq. (96)] thus... 

The use of natural rubber latex to form graft copolymers (and eventually IPN-related materials) was one of the earlier methods of preparing rubber/plastic compositions. " " These materials are known as Heveaplus, which is a generic name of a series of raw materials made by graft copolymerization with other polymeric or resinous substances. Heveaplus MG, prepared by polymerizing methyl methacrylate in the rubber latex, has attracted the most attention. 

Graft copolymers of natural rubber and poly(methyl methacrylate) in latex form are marketed as Heveaplus . The rubber latex is treated with methyl methacrylate in the presence of an initiator (e.g., hydroperoxide activated by a... 

MG 30 and MG 49 are graft copolymers containing the percentage amounts of methyl methacrylate indicated by the numbers. They are available either as latices or as solid rubbers from suppliers in Malaysia. Alternative supplies are often available from specialist manufacturers in consuming countries. Although there is always present some methyl methacrylate homopolymer, at least 50% is grafted. The latex contains 50% total solids and is easily manufactured in an adhesives factory. Table 5 gives the recipe for preparation of the latex. ... 

Styrene and methyl methacrylate in the presence of the rubber seed latex particles. Finally, glycidyl methacrylate was grafted onto the composite latex particles. The emulsion polymerizations were stabilized by sodium dihexyl sulfosuccinate and initiated by potassium persulfate. The functionalized composite polymer particles, which served as an impact modifier, were blended with polyamide-6, and these particles were dispersed well in the matrix of polyamide-6. 

Graft copolymers of natural rubber and poly(methyl methacrylate) in latex form have been produced on a small scale. The rubber latex is treated with methyl methacrylate in the presence of an initiator (e.g. hydroperoxide activated by a polyamine). Generally, equal weights of rubber (dry weight) and monomer are used and the product consists of about 80% graft copolymer, 10% polyisoprene and 10% poly(methyl methacrylate). The material gives rise to vulcanizates with excellent physical properties at high hardness levels. 

Two other derivatives that have received attention are thermoplastic NR (TPNR) blends and epoxidized NR (ENR). TPNRs often are blends of NR with polypropylene [15], Applications include automotive components and floor tiles. ENR-50, with 50 mol% epoxidized double bonds, can be used where oil resistance or air impermeability is needed together with high strength [16], Some applications include hoses and seals. The grafting of methyl methacrylate on NR has been carried out on a commercial scale by polymerizing the monomer in a rubber latex. The primary use of the grafted material is as an additive to improve flow of unmodified rubber. 

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