Graft polymers polybutadiene

To produce the Type 2 polymers, styrene and acrylonitrile are added to polybutadiene latex and the mixture warmed to about 50°C to allow absorption of the monomers. A water-soluble initiator such as potassium persulphate is then added to polymerise the styrene and acrylonitrile. The resultant materials will be a mixture of polybutadiene, polybutadiene grafted with acrylonitrile and styrene, and styrene-acrylonitrile copolymer. The presence of graft polymer is essential since straightforwsird mixtures of polybutadiene and styrene-acrylonitrile copolymers are weak. In addition to emulsion processes such as those described above, mass and mass/suspension processes are also of importance. 

The tendency of polybutadiene to undergo chain transfer reactions can be used for the preparation of impact-resistance polymer where polystyrene has been grafted to polybutadiene as under ... 

The concept is similar to the grafting of plants in botany. To form a styrene-butadiene graft polymer, already polymerized butadiene is dissolved in monomeric styrene and an initiator is added. Because polybutadiene readily undergoes chain transfer at the allylic sites, polystyrene chains grow on the polybutadiene backbone. This forms high impact polystyrene, a low cost plastic that is otherwise too brittle without the grafting. 

Unlike simple mixtures of polystyrene and polybutadiene such blends can be thermoplastically processed without phase separation ( splicing ) Furthermore, they can to a certain extent withstand mechanical impact without disintegration. This is because the above-mentioned graft polymers function also as compatibilizer at the borderline of the hard phase and the rubber-elastic dispersed phase (already at concentrations below 3%). 

Graft Polymers. The procedure used was described by Cummings (3). To a quantity of commercially available polybutadiene latex (52.3% solids) containing 50 parts of rubber was added sufficient deionized water to increase the water content to 180 parts. The diluted latex was heated to 60°C. Potassium persulfate (0.3 part) and monomers (styrene, acrylonitrile, DBPF 50 parts) were added, and poly-... 

The styrene-acrylonitrile copolymers were prepared in the form of a thin film. The graft polybutadiene solution was coated on a glass slide. But, for the graft polymer containing acrylonitrile, it was undesirable to use the glass slide because of the induced orientation, therefore, we used a Mylar film to support a thick smooth film of the graft rubber. 

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. 

Graft Polymer Studies on Model System. Methyl methacrylate/ styrene ratio, chain transfer agent level, and type of initiator system were evaluated in graft polymer using Firestone 2004 polybutadiene latex as a model. 

Figure 5. Ballistic impact of blends of graft polymers made from 360- and 2000-A polybutadiene latexes...

Rubber Content. To analyze the effect of rubber content we made a graft polymer with 25% polybutadiene rubber and a high degree of graft using the 360-A polybutadiene latex. Essentially the same procedure that developed the 15% rubber graft was followed. The rubber/ monomer ratio was changed to 25/75, and three surfactant systems were evaluated (Table X). 

A high-impact polystyrene that has much better optical clarity than that obtained by usual blending or grafting techniques can be prepared by our technique. Polymers containing 90-95% styrene grafted to polybutadiene rubber by use of 12 mmole RLi-TMEDA/100 gram polymer showed quite good optical clarity. 

The diameter of the polybutadiene latex particles used in ABS synthesis usually ranges from 0.1 ju to lju, and the polymer is always crosslinked within the particles. Consequently, after grafting, every polybutadiene particle becomes a particle of grafted and crosslinked polymer which is much heavier than the linear copolymer molecules. 

An interesting butadiene-styrene graft polymer can be obtained by adding a radical-type initiator to a reaction mixture containing polybutadiene and monostyrene. The polybutadiene contains a residual double bond which, when attacked by a radical under certain conditions, may open up and provide the initiating site for a poly8t3rrene polymerization. This reaction can be schematically illustrated as follows ... 

Cameron, G.G., Qureshi, M.Y, 1980. Eree-radical grafting of monomers to polydienes 4. Kinetics and mechanism of methyl-methacrylate grafting to polybutadiene. J. Polym. Sci. Part A Polym. Chem. 18(11), 3149-3161. 

A graft polymer chain (Fig. 4c) has a linear backbone and randomly distributed side chains. The side chains (which can be very long) are structurally distinct from the main chain but can be homopolymers or copolymers. A well-known example of a graft polymer is high-impact polystyrene (HIPS), where polybutadiene (PB) side chains are grafted to the PS backbone. 

In addition to ABS, with polybutadiene as the elastifying component, there is another forerunner among the polymer products formulated for low-temperature impact resistance, PVC-U. Elastifying ligands include EVAC, EVAC/VC graft polymer, PAEA C (polyacrylic acid ester/vinyl chloride copolymer), ACE (acrylic ester/MMA graft polymer) as well as the chlorinated low-pressure polyethylene PE-C in use for over 35 years. All of the polymer blends listed here are suitable for outdoor applications since they contain no unsaturated components. Polybutadiene-modified products are better suited to interior applications, for example MBS, a methylmethacrylate/butadiene/styrene graft polymer [55]. 

Blends of TPUs and Acrylonitrile-Polybutadiene-Styrene graft polymer (ABS) have been studied by a number of researchers [14-16]. The structures of the blends are very complex due to the complex polyblend of ABS, in which there is a rigid SAN copolymer with a rubbery graft butadiene polymer and the heterophase system of the TPU. The two polymers can benefit each other, as shown in Table 1. 

Mechanical or Physical Blends, While a blend is a physical mixture rather than a definite reacted species, many block and graft polymers contain greater or lesser quantities of homopolymer. In particular, the only slightly grafted HiPS and ABS materials are usually listed together with the polybutadiene/polystyrene mechanical blends. It is convenient to introduce a special designation for blended materials A simple example is... 

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