Impact grafted onto polybutadiene

Transparent, Impact-Resistant, Styrene/ Methyl Methacrylate Copolymer Grafted onto Polybutadiene... 

Modification of Mechanical Properties. Application of these concepts is illustrated by impact polystyrene polystyrene (PS) grafted onto polybutadiene (PBD) permits as much as 40% PBD in PS to be incorporated whereas, in the absence of the graft copolymer, incompatibility is detectable by stratification when more than 10% elastomer is blended with PS (Diagram 3). Acrylonitrile-... 

Acrylonitrile-Butadiene-Styrene (ABS) Terpolymer. The acrylonitrile and styrene copolymer is grafted onto polybutadiene. The properties of SAN are combined with a greatly improved impact resistance and heat distortion resistance. ABS terpolymers And application as engineering plastics, in household appliances, luggage, telephone housings, automotive parts, and many more. 

High Impact Polystyrene is properly treated as a ternary system and not as a binary blend of polystyrene and polybutadiene. The third component is graft copolymer (i.e., styrene grafted onto polybutadiene) formed during polymerization. It thus resembles the ternary systems involving block copolymers described in the previous sections. 

Impact polystyrene contains polybutadiene added to reduce brittleness. The polybutadiene is usually dispersed as a discrete phase in a continuous polystyrene matrix. Polystyrene can be grafted onto rubber particles, which assures good adhesion between the phases. 

Graft polymerization of the monomer from which the matrix is built-up, onto the dispersed phase, e.g., graft polymerization of styrene onto polybutadiene during the preparation of impact-resistant polystyrene,... 

High-impact polystyrene (HIPS) is a graft copolymer. It is a PS backbone with chains of polybutadiene grafted onto the backbone. PS gives the material strength, but the rubbery polybutadiene chains give resilience to make it less brittle. 

Acrylonitrile is also commonly found in impact modifiers, such as the acrylonitrile-butadiene-styrene (ABS) type, produced by emulsion polymerisation. Polybutadiene seed latex particles are grafted onto styrene and acrylonitrile in a seeded emulsion polymerisation process. As the styrene-acrylonitrile copolymer shell forms, polybutadiene domains are spontaneously separated within. The resulting impact modifier particles are subsequently compounded with polystyrene to product high impact polystyrene (HIPS). The impact modification properties of the latex particles may be optimised through varying the butadiene content, the particle size and structure, and the shell molecular weight. A basic formulation for an ABS impact modifier is given in Table 6. 

For rubber-modified, high-impact PS (HIPS), polybutadiene (PB) is dissolved in the styrene monomer (5-10%) and grafting onto the PB takes place. The copolymer styrene/acrylonitrile (SAN) is made in a diluent with controlled addition of S and AN using a free-radical initiator. Copolymers with high AN (70-80%) have low gas permeability and are used for containers. Acrylonitrile/butadiene/styrene (ABS) copolymers are often made in water using a polybutadiene latex together with AN and S monomers and a water-soluble initiator (e.g. persulphate). The random copolymer rubber 75% styrene/25% butadiene (SBR) is also made as an aqueous emulsion using a persulphate initiator. 

Transparency is often required. This is achieved by arranging that the particle size of the modifier to be below that of the wavelength of visible light (0.4-0.8 pm). This can normally be achieved by emulsion polymerisation, e.g., polybutadiene, polystyrene. Adhesion and surface compatibility between the polymer and modifier can be achieved by surface grafting of polar groups, e.g., acrylonitrile, various acrylates, onto the impact modifier surface before blending. 

The most important example of graft eopolymers having polystyrene sidearms is high-impaet polystyrene (HIPS), in whieh polystyrene is the continuous phase and polybutadiene grafted with polystyrene forms the separated phase. Grafting occurs when some of the radicals react with the double bonds in polybutadiene [182-186], Grafting is also possible onto poly(ethene-co-propene-co-butadiene) [187] and polyacrylic ester [188], High-impact polystyrene is reviewed in detail in Ref. [189]. 

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