Grafted onto polybutadiene

Graft copolymers are also used as compatibilizers to tie together different phases. HIPS contains PS grafted onto polybutadiene backbones. This allows stress or strain to be transferred from the PS to the polybutadiene phase transferring energy that might break the brittle PS to the more flexible polybutadiene phase. That is why HIPS is stronger than PS itself. 

Figure 17. Styrene and acrylonitrile grafted onto polybutadiene vs. monomer converted, doubly precipitated...

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. 

Oligomeric ethylene oxide terminated with l,2,4-triazoline-3,5-dione has been grafted onto polybutadiene at room temperature in a mixture of tetrahydrofuran and ethylene chloride (53). The product had a broad molecular weight distribution, and energy absorption maxima related to the glass transition temperature of each polymer were apparent. 

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. 

The proportion of styrene grafted onto polybutadiene is controlled by the ratio of rubber to styrene in the reaction mixture. The cis and trans isomers of polybutadiene have equal activity. Normal first-order kinetics for styrene consumption were observed, and the molecular weight dependence on monomer and initiator concentrations were as expected. Through careful separation, a decrease in the molecular weight of the ungrafted rubber was noted. 

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. 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

Grafting of styrene (ST) onto polybutadiene (PB) can occur in two ways Via a chain-transfer reaction with an allylic hydrogen of the 1,4- and the 1,2-units (Case 1) via copolymerization with C=C-double bounds of polybutadiene, in particular with the vinyl groups of the 1,2-units (Case 2) ... 

The production of ABS and SAN resins consumes the second largest quantity of acrylonitrile. The ABS resins are produced by grafting acrylonitrile and styrene onto polybutadiene or a styrene-butadiene copolymer and contain about 25 wt% acrylonitrile. These products are used to make components for automotive and recreational vehicles, pipe fittings, and appliances. The SAN resins are styrene-acrylonitrile copolymers containing 25-30 wt% of acrylonitrile. The superior clarity of SAN resin allows it to be used in automobile instrument panels, for instrument lenses and for houseware items (Langvardt, 1985 Brazdil, 1991). 

Step 2—Polybutadiene rubber is further polymerized, but in the presence of styrene and acrylonitrile monomers. This is done in low-pressure reactors under a nitrogen atmosphere. In this operation, the monomers are grafted onto the rubber backbone through the residual unsaturation remaining from the first step. 

Similar polymers, slightly less perfect, are the umbrella star copolymers [101]. These polymers are based on a central polystyrene star with 25 arms. An average of five polybutadiene or poly(2-vinylpyridine) branches are grafted onto the end of each arm. Since these polymers are models for block copolymer micelles their properties have been studied in selective solvents. In particular, the PBd-PS umbrella-star copolymers are monomolecularly dissolved in non-solvents for the core-forming polystyrene. 

Direction substitution of element notation (Equation 10) representing the grafting of polystyrene side chains onto polybutadiene backbone. An AB-crosslinked copolymer of Bamford and Eastmond (14a)... 

The rubber particles were examined with an electron microscope after the sample was treated with osmium tetroxide (27). The micrograph (Figure 7) clearly indicates the porous nature of the rubber phase and the occlusion of polystyrene. We therefore classify this type of rubber phase as filled graft rubber. Since grafting takes place before and after the rubber chain is coiled, therefore, for this case, the monomer is grafted onto the rubber both within and without the rubber phase. Polybutadiene is thus made more compatible to the polymer matrix surrounding the rubber phase and the polymer filling the rubber phase. Here we have an... 

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