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. 

GopolymeriZation Initiators. The copolymerization of styrene and dienes in hydrocarbon solution with alkyUithium initiators produces a tapered block copolymer stmcture because of the large differences in monomer reactivity ratios for styrene (r < 0.1) and dienes (r > 10) (1,33,34). In order to obtain random copolymers of styrene and dienes, it is necessary to either add small amounts of a Lewis base such as tetrahydrofuran or an alkaU metal alkoxide (MtOR, where Mt = Na, K, Rb, or Cs). In contrast to Lewis bases which promote formation of undesirable vinyl microstmcture in diene polymerizations (57), the addition of small amounts of an alkaU metal alkoxide such as potassium amyloxide ([ROK]/[Li] = 0.08) is sufficient to promote random copolymerization of styrene and diene without producing significant increases in the amount of vinyl microstmcture (58,59). 

Pig. 13. Incorporation of photosensitive ketone groups into PS during manufacture by copolymerization of styrene and vinyl ketone. 

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). 

SBR is produced by addition copolymerization of styrene and butadiene monomers in either emulsion or solution process. The styrene/butadiene ratio controls the glass transition temperature (To) of the copolymer and thus its stiffness. T ... 

By means of a ring-opening polymerization of the condensation type Vlasov et al. [50] synthesized polypeptide based MAIs with azo groups in the polymeric backbone. The method is based on the reaction of a hydracide derivative of AIBN and a N-carboxy anhydride. Containing one central azo group in the polymer main chain, the polymeric azo initiator was used for initiating block copolymerizations of styrene and various methacrylamides. 

The copolymerization of styrene and the dienes in hydrocarbons was first investigated by Korotkov 43) who reported an unexpected phenomenon. The polymeriza-... 

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. 

Yin et al. [73,74] prepared new microgel star amphiphiles and stndied the compression behavior at the air-water interface. Particles were prepared in a two-step process. First, the gel core was synthesized by copolymerization of styrene and divinylbenzene in diox-ane using benzoylperoxide as initiator. Microgel particles 20 run in diameter were obtained. Second, the gel core was grafted with acrylic or methacryUc acid by free radical polymerization, resulting in amphiphilic polymer particles. These particles were spread from a dimethylformamide/chloroform (1 4) solution at the air-water interface. tt-A cnrves indicated low compressibility above lOmNm and collapse pressnres larger than 40 mNm With increase of the hydrophilic component, the molecnlar area of the polymer and the collapse pressure increased. 

Fig. 27.—The rate of copolymerization of styrene and methyl methacrylate at 60°C in the presence of azo-bis-isobutyronitrile (1 g./l.) plotted against the mole fraction of styrene. Broken line has been calculated from Eq. (26) assuming < = 1. Solid line represents calculated curve for 0 = 13. (Walling. q...

Polystyrene-g-poly(ethylene oxide) was synthesized by the copolymerization of styrene and styrenic PEO with CpTiCb/MAO catalyst [190]. In this case the macromonomer was prepared by first reacting the sodium salt of PEO-OH with NaH and then with a 5-fold amount of p-chloromethyl styrene. 

A similar mechanism of chain oxidation of olefinic hydrocarbons was observed experimentally by Bolland and Gee [53] in 1946 after a detailed study of the kinetics of the oxidation of nonsaturated compounds. Miller and Mayo [54] studied the oxidation of styrene and found that this reaction is in essence the chain copolymerization of styrene and dioxygen with production of polymeric peroxide. Rust [55] observed dihydroperoxide formation in his study of the oxidation of branched aliphatic hydrocarbons and treated this fact as the result of intramolecular isomerization of peroxyl radicals. 

The use of a single-stage CSTR for HF alkylation of hydrocarbons in a special forced-circulation shell-and-tube arrangement (for heat transfer) is illustrated by Perry et al. (1984, p. 21-6). The emulsion copolymerization of styrene and butadiene to form the synthetic rubber SBR is carried out in a multistage CSTR. 

The copolymerization of styrene and maleic anhydride was studied by the spintrapping technique using 2-methyl-2-nitrosopropane as a spin trap. Four types of ESR spectra were obtained, of which three corresponded to trapping of the growing polymer chain at a centre originating from the styrene part or from two centres originating from the maieic anhydride part. The fourth EPR spectrum may be due to a cyclic flve-membered aminoxyl or a six-membered 1,2-oxazine radical cation. ... 

Finally, the lithiation of a soluble chloromethylated polystyrene 16 (prepared by AIBN-indnced copolymerization of styrene and 4-chloromethylstyrene in a 3 1 molar ratio) with lithinm and a catalytic amonnt of DTBB (10%) in THF at —78 °C gave the expected... 

A few examples will illustrate the utility of Eqs. 6-33 and 6-34. Figure 6-3 shows the behavior observed in the radical copolymerization of styrene and methyl methacrylate. F and h i are the instantaneous copolymer compositions for the instantaneous feed... 

In such cases the polymerization can be taken to relatively high conversion without change in composition of the copolymer formed (see Example 3-37). In the copolymerization diagram the azeotrope corresponds to the intersection point of the copolymerization curve with the diagonal. For example, from Fig. 3.4 it may be seen that in the radical copolymerization of styrene and methyl methacrylate the azeotropic composition corresponds to 53 mol% of styrene. 

In the radical copolymerization of styrene and methyl methacrylate the reactivities are about the same, but for anionic initiation of an equimolar mixture of the two monomers the incorporation of methyl methacrylate is much preferred, while for cationic initiation of the same mixture the copolymer contains mostly... 

Styrene monoliths have been prepared by thermally (AIBN or benzoyl peroxide) initiated copolymerization of styrene and divinylbenzene to result mechanically stable, hydrophobic column supports for RPC as well as IP-RP-HPLC and CEC application [24,49,134-140]. 

Mixed dimerization also affects the kinetics of anionic copolymerization of styrene and para-methyl styrene, a system studied by O Driscoll(24). The reaction was performed in benzene with lithium counter-ions and the plots of In.[styrene] or In(para-methyl styrene] vs. time were both linear. Their slopes,... 

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). 

The formation of a three-dimensional network in the copolymerization of styrene and divinylbenzene. Collection Czech. Chem. Commun. 32,1182 (1967). 

POROS media, made by copolymerization of styrene and divinylben-zene, have high mechanical strength and are resistant to many solvents and chemicals. The functional surface chemistry of the particles can be modified to provide supports for many types of chromatography, including ion exchange, hydrophobic interaction, immobilized metal affinity, reversed... 

These results show that the 1,2-polymerization of butadiene requires a less anionic catalyst than the anionic polymerization of styrene. Tobolsky and Rogers (58) studied the same effects of catalyst anionicity on the copolymerization of styrene and isoprene. They found that the increased anionic character of the lithium-THF combination relative to butyllithium catalysts increased the styrene content of the polymer as well as decreased the 1.4-structure of the polyisoprene. 

STYRENE-MALEIC ANHYDRIDE. A thermoplastic copolymer made by the copolymerization of styrene and maleic anhydride. Two types of polymers are available—impact-modified SMA terpolymer alloys (Cadon ) and SMA copolymers, with and without rubber impact modifiers (Dylark ). These products are distinguished by higher heat resistance than the parent styrenic and ABS families. The MA functionality also provides improved adhesion to glass fiber reinforcement systems. Recent developments include lerpolymer alloy systems with high-speed impact performance and low-temperature ductile fail characteristics required by automotive instrument panel usage. 

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