Acrylonitrile copolymerization of styrene and

In all manufacturing processes, grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of an elastomer. Ungrafted styrene—acrylonitrile copolymer is formed during graft polymerization and/or added afterward. 

Solution Polymerization These processes may retain the polymer in solution or precipitate it. Polyethylene is made in a tubular flow reactor at supercritical conditions so the polymer stays in solution. In the Phillips process, however, after about 22 percent conversion when the desirable properties have been attained, the polymer is recovered and the monomer is flashed off and recyled (Fig. 23-23 ). In another process, a solution of ethylene in a saturated hydrocarbon is passed over a chromia-alumina catalyst, then the solvent is separated and recyled. Another example of precipitation polymerization is the copolymerization of styrene and acrylonitrile in methanol. Also, an aqueous solution of acrylonitrile makes a precipitate of polyacrylonitrile on heating to 80°C (176°F). 

The heterogeneous copolymerization of styrene and acrylonitrile in various diluents as reported by Riess and Desvalois (22). Although the copolymer composition in these studies was not strongly influenced by the diluent choice, the preferential adsorption of acrylonitrile monomer onto the polymer particles shifted the azeotropic copolymerization point from the 38 mole % acrylonitrile observed in solution to 55 mole % acrylonitrile. 

High impact strength thermoplastic resins can be prepared by mixing a styrene/acrylonitrile copolymer with rubber particles. In general, the styrene/acrylonitrile copolymer is prepared by the graft copolymerization of styrene and acrylonitrile in the presence of rubber itself (17). 

Commercial ABS is prepared primarily by free-radical emulsion copolymerization of styrene and acrylonitrile in the presence of polybutadiene latex (3). This method was therefore adapted for the preparation of ABS and MBS terpolymers and an intermediate AMBS tetrapolymer under similar conditions (Table I). Polymerizations were charged into 12-ounce crown-cap bottles, sparged and flushed with nitrogen, and... 

So trustworthy arguments furnished by the authors of Ref. [283] testify that the copolymerization of styrene and acrylonitrile in toluene solution can be fairly... 

Hasha DL, Priddy DB, Rudolf PR, Stark EJ, De Pooter M and Van Damme F (1992) Oligomer formation and the mechanism of initiation in the spontaneous copolymerization of styrene and acrylonitrile. Macromolecules 25 3046-51. 

In some cases it is desirable to conduct a copolymerization in the presence of a solvent. Table III illustrates the effect of solvent concentration on the copolymerization of styrene and acrylonitrile. Higher concentrations of solvent produced a pronounced lowering of the rate without changing the molecular weight as measured by the solution viscosity of the copolymer. 

The copolymerization of styrene and acrylonitrile in the presence of AlEt under UV irradiation yields equimolar, alternating copolymers when the initial comonomer charge is equimolar or contains excess acrylonitrile and products with compositions intermediate between that of the equimolar copolymer and that of the radical copolymer when the initial charge is rich in styrene (Table III) (lO). The intermediate compositions may represent mixtures of equimolar and radical copolymers, block copolymers generated as shown in Eq. (6)-(l0) or random copolymers resulting from copolymerization of complexes and monomers. 

Styrene is frequently used as part of some terpolymers with large practical utilization. One such copolymer is acrylonitrile-butadiene-styrene terpolymer (ABS). Usually it is made as poly(l-butenylene-graft-l-phenylethylene-co-cyanoethylene). This form of the copolymer can be made by grafting styrene and acrylonitrile directly on to the polybutadiene latex in a batch or continuous emulsion polymerization process. Grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of polybutadiene. The degree of grafting is a function of the 1,2-vinyl content of the polybutadiene, monomer concentration, extent of conversion, temperature and mercaptan concentration (used for crosslinking). The emulsion polymerization process involves two steps production of a rubber latex and subsequent polymerization of styrene and acrylonitrile in the presence of the rubber latex to produce an ABS latex. 

Solution Polymerization These processes may retain the polymer in solution or precipitate it. Examples include polyethylene, the copolymerization of styrene and acrylonitrile in methanol, the aqueous solution of acrylonitrile to precipitate polyacrylonitrile. 

Table XVIII. Copolymerization of Styrene and Acrylonitrile in Presence of ZnCl2 and Cellulose...

Acrylonitrile/Butadiene/Styrene (ABS) Acry-lonitrile/butadiene/styrene (ABS) polymers are not true terpolymers. As HIPS they are multipolymer composite materials, also called polyblends. Continuous ABS is made by the copolymerization of styrene and acrylonitrile (SAN) in the presence of dissolved PB rubber. It is common to make further physical blends of ABS with different amounts of SAN copolymers to tailor product properties. Similar to the bulk continuous HIPS process, in the ABS process, high di-PB (>50%, >85% 1,4-addition) is dissolved in styrene monomer, or in the process solvent, and fed continuously to a CSTR where streams of AN monomer, recycled S/AN blends from the evaporator and separation stages, peroxide or azo initiators, antioxidants and additives are continuously metered according to the required mass balance to keep the copolymer composition constant over time at steady state. 

Azeotropic copolymerization of styrene and acrylonitrile in methanol Poly(vinylchloride)... 

Jaisinghani and Ray (40) also predicted the existence of three steady states for the free-radical polymerization of methyl methacrylate under autothermal operation. As their analysis could only locate unstable limit cycles, they concluded that stable oscillations for this system were unlikely. However, they speculated that other monomer-initiator combinations could exhibit more interesting dynamic phenomena. Since at that time there had been no evidence of experimental work for this class of problems, their theoretical analysis provided the foundation for future experimental work aimed at validating the predicted phenomena. Later studies include the investigations of Balaraman et al. (43) for the continuous bulk copolymerization of styrene and acrylonitrile, and Kuchanov et al. (44) who demonstrated the existence of sustained oscillations for bulk copolymerization under non-isothermal conditions. Hamer, Akramov and Ray (45) were first to predict stable limit cycles for non-isothermal solution homopolymerization and copolymerization in a CSTR. Parameter space plots and dynamic simulations were presented for methyl methacrylate and vinyl acetate homopolymerization, as well as for their copolymerization. The copolymerization system exhibited a new bifurcation diagram observed for the first time where three Hopf bifurcations were located, leading to stable and unstable periodic branches over a small parameter range. Schmidt, Clinch and Ray (46) provided the first experimental evidence of multiple steady states for non-isothermal solution polymerization. Their... 

The copolymerization of styrene and acrylonitrile to give a random styrene-acrylonitrile copolymer. 

Fig. 26. Structures of the AjS trimer diastereomer pairs formed during the spontaneous copolymerization of styrene and acrylonitrile...

ASA is the acronym for acrylate rubber-modified SAN copolymer. It is a terpolymer that can be produced by either a reaction process or a graft process. ASA is usually made by introducing a grafted acrylic ester elastomer during the copolymerization of styrene and acrylonitrile, known as SAN. SAN is described later in this chapter. The finely divided... 

Another system of great interest was the copolymerization of styrene and acrylonitrile, which finds important applications in industry. The control was essentially ensured by TEMPO,particularly at the azeotropic composition at which no composition drift is expected. Suspension copolymerization was considered with the same success as in bulk. ... 

Figure 4 Triad fractions for bulk copolymerization of styrene and acrylonitrile at 60 C. Xs = mole fraction S in the monomer A = styrene centred triads, B = acrylonitrile centred triads penultimate model----. ...

Suspension Copolymerization of Styrene and Acrylonitrile 41-11. Suspension Copolymerization of Acrylamide and Acrylic Acid 41-12. Polymerization of Acrylamide in Aqueous Solution 41-13. Continuous-Solution Polymerization of -Vinylpyrrolidone... 

Suspension Graft Copolymerization of Styrene and Acrylonitrile to Polybutadiene Latex... 

Table IS lypical Recipe Suspension Copolymerization of Styrene and Acrylonitrile ...

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