Methylstyrene acrylonitrile

SAN modifier [ACRYLONITRILE POLYMERS - SURVEY AND SAN (STYRENE-ACRYLONITRILECO-POLYMERS)] (Vol 1) Poly( a-methylstyrene) [25014-31-7]... 

Such copolymers of oxygen have been prepared from styrene, a-methylstyrene, indene, ketenes, butadiene, isoprene, l,l-diphen5iethylene, methyl methacrjiate, methyl acrylate, acrylonitrile, and vinyl chloride (44,66,109). 1,3-Dienes, such as butadiene, yield randomly distributed 1,2- and 1,4-copolymers. Oxygen pressure and olefin stmcture are important factors in these reactions for example, other products, eg, carbonyl compounds, epoxides, etc, can form at low oxygen pressures. Polymers possessing dialkyl peroxide moieties in the polymer backbone have also been prepared by base-catalyzed condensations of di(hydroxy-/ f2 -alkyl) peroxides with dibasic acid chlorides or bis(chloroformates) (110). 

Blends of poly(vinyl chloride) (PVC) and a-methylstyrene—acrylonitrile copolymers (a-MSAN) exhibit a miscibiUty window that stems from an LCST-type phase diagram. Figure 3 shows how the phase-separation temperature of 50% PVC blends varies with the AN content of the copolymer (96). This behavior can be described by an appropriate equation-of-state theory and interaction energy of the form given by equation 9. 

The use of TAG as a curing agent continues to grow for polyolefins and olefin copolymer plastics and mbbers. Examples include polyethylene (109), chlorosulfonated polyethylene (110), polypropylene (111), ethylene—vinyl acetate (112), ethylene—propylene copolymer (113), acrylonitrile copolymers (114), and methylstyrene polymers (115). In ethylene—propylene copolymer mbber compositions. TAG has been used for injection molding of fenders (116). Unsaturated elastomers, such as EPDM, cross link with TAG by hydrogen abstraction and addition to double bonds in the presence of peroxyketal catalysts (117) (see Elastol rs, synthetic). 

Styrene Copolymers. Acrylonitrile, butadiene, a-methylstyrene, acryUc acid, and maleic anhydride have been copolymerized with styrene to yield commercially significant copolymers. Acrylonitrile copolymer with styrene (SAN), the largest-volume styrenic copolymer, is used in appHcations requiring increased strength and chemical resistance over PS. Most of these polymers have been prepared at the cross-over or azeotropic composition, which is ca 24 wt % acrylonitrile (see Acrylonithile polya rs Copolyp rs). 

High heat ABS resins are produced by adding a third monomer to the styrene and acrylonitrile to stiffen the polymer backbone, thus raising the T. Two monomers used commercially for this purpose are a-methylstyrene (85) and /V-pheny1ma1eimide (86). 

Fig. 8. Thermogravimetric analysis of polymers and copolymers of styrene in nitrogen at 10°C/min A represents PS B, poly(vinyltoluene) C, poly(a-methylstyrene) D, poly(styrene-i (9-acrylonitrile), with 71.5% styrene E, poly(styrene-i (9-butadiene), with 80% styrene and F,...

Several alkenes are converted to aziridines by treating with oxaziridine (52) at elevated temperatures. Styrene, a-methylstyrene and their derivatives substituted in the benzene ring react smoothly, and so do 1,1-diphenylethylene, indene and acrylonitrile (74KGS1629). 

The first approach has been important commercially. The monomer most commonly used is a-methylstyrene (see Section 16.11), whose polymer has a Tg of about 120°C. The heat distortion temperature of the resultant-ABS type polymer will depend on the level of replacement of styrene by the a-methyl-styrene. (It may be noted in passing that a-methylstyrene-acrylonitrile binary copolymers have been available as alternatives to styrene-acrylonitrile materials but have not achieved commercial significance.)... 

Waters61 have measured relative rates of p-toluenesulfonyl radical addition to substituted styrenes, deducing from the value of p + = — 0.50 in the Hammett plot that the sulfonyl radical has an electrophilic character (equation 21). Further indications that sulfonyl radicals are strongly electrophilic have been obtained by Takahara and coworkers62, who measured relative reactivities for the addition reactions of benzenesulfonyl radicals to various vinyl monomers and plotted rate constants versus Hammett s Alfrey-Price s e values these relative rates are spread over a wide range, for example, acrylonitrile (0.006), methyl methacrylate (0.08), styrene (1.00) and a-methylstyrene (3.21). The relative rates for the addition reaction of p-methylstyrene to styrene towards methane- and p-substituted benzenesulfonyl radicals are almost the same in accord with their type structure discussed earlier in this chapter. 

Applications As the basic process of electron transfer at an electrode is a fundamental electrochemical principle, polarography can widely be applied. Polarography can be used to determine electroreductible substances such as monomers, organic peroxides, accelerators and antioxidants in solvent extracts of polymers. Residual amounts of monomers remain in manufactured batches of (co)polymers. For food-packaging applications, it is necessary to ensure that the content of such monomers is below regulated level. Polarography has been used for a variety of monomers (styrene, a-methylstyrene, acrylic acid, acrylamide, acrylonitrile, methylmethacrylate) in... 

A heterogeneous Pd catalyst dispersed on supports such as o-A1203, C, MgO and CaC03 was found to be an recyclable and selective catalyst for heterogeneous Heck arylation (an important method of C-C bond formation - Chapt. 11) of several olefins (styrene, a-methylstyrene, 1-decene, acrylonitrile, etc.) with iodobenzene [45], Scheme 10.5. 

The results of the olefin oxidation catalyzed by 19, 57, and 59-62 are summarized in Tables VI-VIII. Table VI shows that linear terminal olefins are selectively oxidized to 2-ketones, whereas cyclic olefins (cyclohexene and norbomene) are selectively oxidized to epoxides. Cyclopentene shows exceptional behavior, it is oxidized exclusively to cyclopentanone without any production of epoxypentane. This exception would be brought about by the more restrained and planar pen-tene ring, compared with other larger cyclic nonplanar olefins in Table VI, but the exact reason is not yet known. Linear inner olefin, 2-octene, is oxidized to both 2- and 3-octanones. 2-Methyl-2-butene is oxidized to 3-methyl-2-butanone, while ethyl vinyl ether is oxidized to acetaldehyde and ethyl alcohol. These products were identified by NMR, but could not be quantitatively determined because of the existence of overlapping small peaks in the GC chart. The last reaction corresponds to oxidative hydrolysis of ethyl vinyl ether. Those olefins having bulky (a-methylstyrene, j8-methylstyrene, and allylbenzene) or electon-withdrawing substituents (1-bromo-l-propene, 1-chloro-l-pro-pene, fumalonitrile, acrylonitrile, and methylacrylate) are not oxidized. 

Amresco acryl-40, see Acrylamide AMS, see a-Methylstyrene n-Amyl acetate, see Amyl acetate Amyl acetic ester, see Amyl acetate Amyl acetic ether, see Amyl acetate Amylene, see 1-Pentene a-n-Amylene, see 1-Pentene p-n-Amylene, see cis-2-Pentene cis-p-Amylene, see cis-2-Pentene frans-p-Amylene, see trans-2-Venlene sec-Amyl ethanoate, see Amyl acetate Amyl ethyl ketone, see 5-Methyl-3-heptanone Amyl hydride, see Pentane Amyl methyl ketone, see 2-Heptanone n-Amyl methyl ketone, see 2-Heptanone AN, see Acrylonitrile Anaesthetic ether, see Ethyl ether Anamenth, see Trichloroethylene Anduron, see Diuron Anesthenyl, see Methylal Anesthesia ether, see Ethyl ether Anesthetic ether, see Ethyl ether Anhydrous ammonia, see Ammonia Aniline oil, see Aniline Anilinobenzene, see 4-Aminobiphenyl Anilinomethane, see Methylaniline 2-Anidine, see o-Anisidine 4-Anisidine, see p-Anisidine 2-Anisylamine, see o-Anisidine... 

Monomers which can add to their own radicals are capable of copolymerizing with SO2 to give products of variable composition. These include styrene and ring-substituted styrenes (but not a-methylstyrene), vinyl acetate, vinyl bromide, vinyl chloride, and vinyl floride, acrylamide (but not N-substituted acrylamides) and allyl esters. Methyl methacrylate, acrylic acid, acrylates, and acrylonitrile do not copolymerize and in fact can be homopolymer-ized in SO2 as solvent. Dienes such as butadiene and 2-chloro-butadiene do copolymerize, and we will be concerned with the latter cortpound in this discussion. 

Many substituents stabilize the monomer but have no appreciable effect on polymer stability, since resonance is only possible with the former. The net effect is to decrease the exothermicity of the polymerization. Thus hyperconjugation of alkyl groups with the C=C lowers AH for propylene and 1-butene polymerizations. Conjugation of the C=C with substituents such as the benzene ring (styrene and a-methylstyrene), and alkene double bond (butadiene and isoprene), the carbonyl linkage (acrylic acid, methyl acrylate, methyl methacrylate), and the nitrile group (acrylonitrile) similarly leads to stabilization of the monomer and decreases enthalpies of polymerization. When the substituent is poorly conjugating as in vinyl acetate, the AH is close to the value for ethylene. 

Other chemicals present in acrylonitrile production or in other non-acrylonitrile operations on sites of the companies in the epidemiological study by Blair et al. (1998) include acetylene, hydrogen cyanide, propylene, ammonia, acetic acid, phosphoric acid, lactonitrile, hydroquinone, sodium hydroxide, sulfuric acid, acrylamide, acetone cyanohydrin, melamine, methyl methaciydate, zweto-methylstyrene, urea, methacrylonitrile, butadiene, ammonium hydroxide and ammonium sulfate (Zey et al., 1989, 1990a,b Zey McCammon, 1990). 

Dimethylstyrene a-Methylstyrene o-Chlorostyrene Acrylonitrile Methacrylonitrile Acrylic acid... 

Styrene Acrylonitrile a-Methylstyrene Divinylbenzene Basic monomer Basic monomer Instead of styrene Crosslinking agent... 

Styrene Acrylonitrile a-Methylstyrene p-Divinylbenzene Figure 10.1 Monomers used for SAN Copolymers... 

The copolymerization equation is valid if all propagation steps are irreversible. If reversibility occurs, a more complex equation can be derived. If the equilibrium constants depend on the length of the monomer sequence (penultimate effect), further changes must be introduced into the equations. Where the polymerization is subjected to an equilibrium, a-methylstyrene was chosen as monomer. The polymerization was carried out by radical initiation. With methyl methacrylate as comonomer the equilibrium constants are found to be independent of the sequence length. Between 100° and 150°C the reversibilities of the homopolymerization step of methyl methacrylate and of the alternating steps are taken into account. With acrylonitrile as comonomer the dependence of equilibrium constants on the length of sequence must be considered. 

Figure 12. Copolymerization of a-methylstyrene and acrylonitrile. Curves calculated by Equation 5 for 0°, 20°, 50°, 60°, 70°, 80°, and...

Measurements on a-Methylstyrene—Acrylonitrile. Polymerizations were carried out in dilatometers without solvent. Initiator was azobis-isobutyronitrile. At 100 °C the reaction was initiated thermally. At 0° and 20 °C the reaction was carried out in flasks in a thermally controlled room. Yields were below 5%. The composition of the copolymers was calculated from nitrogen determination (Kjeldahl method). In an older reference (29) polymerizations were carried out at 20°, 50°, 60°, and... 

Table VII. Copolymerization Parameters Used To Describe tbe Copolymerization of a-Methylstyrene (Mi) and Acrylonitrile (M2)...

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