Polymerized comonomers

Thus, random copolymerization of cyclic ethers with cyclic amines is not possible. The other limitation, which will be discussed in more detail in a later part of this section, is the reversibility of homo- and/or crosspropagation steps, when one or both comonomers polymerize reversibly. 

The simplest systems involve copolymerization of structurally related pairs of comonomers, polymerizing irreversibly. Copolymerization of different oxetanes [294], thietanes [295], azetidines [296], and oxazolines [297] was studied, the results were interpreted in terms of simple four-parameter copolymerization scheme and the corresponding reactivity ratios for some systems were determined. 

In the second series of polymers, 2-butenes were added as the comonomer. Polymerization activity was little affected when 2-butenes were added at low levels. Density suppression was much less in series 2, indicating (along with NMR measurements) that 2-butene (like other (3-olefins) do not incorporate as easily, resulting in less branching. Nevertheless, 2-butene still caused a pronounced rise in the MI of the polymer, comparable to what was observed in series 1, which does not fit the expected behavior described in Section 7.4. 

Uses Acrylic resin comonomer polymerizes to hard, infusible, insol. ther-moset resin used in UV irradiat coalings vulcanizing agent rubber reforming... 

For most conetwork series, the copolymer composition and architecture were systematically varied by varying the comonomer feed compositions and by changing the order of reagent addition, respectively. Thus, end-linked conetworks based on ABA triblock copolymers of different composition, where usually the length of the mid-block remained constant and the length of the end-blocks was varied, were prepared. Architecture was usually varied at the equimolar composition to provide end-linked conetworks of the ABA triblock, the BAB triblock (prepared by reversing the order of monomer addition relative to the ABA triblock copolymer), and the statistical copolymer (two comonomers polymerized simultaneously) network. In addition to the end-linked conetworks, one randomly cross-linked network was also prepared by the simultaneous terpolymerization of the two comonomers and the cross-linker. This architecture is expected to be similar to... 

Styrene stl- ren [ISV] (1885) (vinyl benzene, phenylethylene, and cinnamene) n. C6H5CH=CH2. a colorless to yellowish oily liquid with a strong, sharp odor, produced by the catalytic dehydrogenation of ethylbenzene. Styrene monomer is easily polymerized by exposure to light, heat, or a peroxide catalyst, and even spontaneously, so a little inhibitor is added if it is to be stored. Styrene is a versatile comonomer, polymerizing readily with many other monomers, and is the active cross-linking monomer in most polyester laminating resins. Mol wt, 104.14 Sp gr, 0.909 mp, -33°C bp, 145-146°C. 

Interpenetrating Polymer Networks (IPN). Polymerization of vinyl and diene monomers over an already formed molecule held in a pol5uner particle represents a special case of copoljnnerization. The interpenetrating polymer networks (qv) thus formed overcome many of the miscibility and other problems associated with physical blends of individual copolymers and leads to new compositions that are useful for coatings, adhesives, and caulks (14). Polychloroprene IPNs have been made by co-curing copolymers of l-chloro-l,3-butadiene [627-22-5], The 1-chloro-l,3-butadiene comonomer polymerizes in a fashion to increase the allylic chloride concentration in the copolymer backbone. The butadiene copolymer with l-chloro-l,3-butadiene (29) and octyl acrylate copolymer (30) improved the low temperature brittleness, oil resistance, and heat resistance of polychloroprene. 

To test the importance of vinyl bond content and copolymerization ability in LCB formation, we carried out a diene copolymerization series with two catalysts having very different comonomer responses, low inherent vinyl bond formation tendency, and very facile hydrogen reactivity. Concentration was kept high to avoid inherent LCB formation in the series. 1,7-Octadiene served as the diene comonomer. Polymerization results are summarized in Table 5. 

The examination of rj t2 values for hundreds of different comonomers polymerized by different mechanisms (2) reveals that in the overwhelming majority of cases these r, r2 values are close to or less than 1 very few examples of ionic processes were found with rjr2>l (J69). For this reason the appearance of a significant number of cases with rir2>t can be regarded as characteristic of complex catalysis. The mentioned tendency is especially pronounced when the comonomers have alkyl groups of different size (ethylene—4-methylpentene-l, pro-pyIene-butene-1, propylene-styrene, propylene-4-methylpentene-l, pro-pylene-vinylcyclohexane). On the other hand, when the alkyl groups are of similar bulkiness (4-methylpentene-l-vinylcyclohexane, 4-methyl-pentene-l-3-methylbutene-l, vinylcyclohexane-styrene), the copolymers obtained are mainly random or have a tendency to alternation. 

White crystals m.p. 162-164 C. ll can be prepared by the fermentation of sugar with the mould Aspergillus lerreus or by healing citra-conic anhydride with water at ISO C. Electrolysis of the potassium salt in solution gives allene. Itaconic acid is used as a comonomer in plastics its esters are polymerized to lubricating oils and plasticizers. 

It is proposed to polymerize the vinyl group of the hemin molecule with other vinyl comonomers to prepare model compounds to be used in hemoglobin research. Considering hemin and styrene to be species 1 and 2, respectively, use the resonance concept to rank the reactivity ratios rj and X2. 

The enthalpy of the copolymerization of trioxane is such that bulk polymerization is feasible. For production, molten trioxane, initiator, and comonomer are fed to the reactor a chain-transfer agent is in eluded if desired. Polymerization proceeds in bulk with precipitation of polymer and the reactor must supply enough shearing to continually break up the polymer bed, reduce particle size, and provide good heat transfer. The mixing requirements for the bulk polymerization of trioxane have been reviewed (22). Raw copolymer is obtained as fine emmb or flake containing imbibed formaldehyde and trioxane which are substantially removed in subsequent treatments which may be combined with removal of unstable end groups. 

In this article the term acrylamide polymer refers to all polymers which contain acrylamide as a major constituent. Consequendy, acrylamide polymers include functionalized polymers prepared from polyacrylamide by postreaction and copolymers prepared by polymerizing acrylamide (2-propenamide, C H NO) with one or more comonomers. 

Acrylamide copolymerizes with many vinyl comonomers readily. The copolymerization parameters ia the Alfrey-Price scheme are Q = 0.23 and e = 0.54 (74). The effect of temperature on reactivity ratios is small (75). Solvents can produce apparent reactivity ratio differences ia copolymerizations of acrylamide with polar monomers (76). Copolymers obtained from acrylamide and weak acids such as acryUc acid have compositions that are sensitive to polymerization pH. Reactivity ratios for acrylamide and many comonomers can be found ia reference 77. Reactivity ratios of acrylamide with commercially important cationic monomers are given ia Table 3. 

In general, acryUc ester monomers copolymerize readily with each other or with most other types of vinyl monomers by free-radical processes. The relative ease of copolymerization for 1 1 mixtures of acrylate monomers with other common monomers is presented in Table 7. Values above 25 indicate that good copolymerization is expected. Low values can often be offset by a suitable adjustment in the proportion of comonomers or in the method of their introduction into the polymerization reaction (86). 

Acrylonitrile (AN), C H N, first became an important polymeric building block in the 1940s. Although it had been discovered in 1893 (1), its unique properties were not realized until the development of nitrile mbbers during World War II (see Elastomers, synthetic, nitrile rubber) and the discovery of solvents for the homopolymer with resultant fiber appHcations (see Fibers, acrylic) for textiles and carbon fibers. As a comonomer, acrylonitrile (qv) contributes hardness, rigidity, solvent and light resistance, gas impermeabiUty, and the abiUty to orient. These properties have led to many copolymer apphcation developments since 1950. 

Acrylonitrile and its comonomers can be polymerized by any of the weU-known free-radical methods. Bulk polymerization is the most fundamental of these, but its commercial use is limited by its autocatalytic nature. Aqueous dispersion polymerization is the most common commercial method, whereas solution polymerization is used ia cases where the spinning dope can be prepared directly from the polymerization reaction product. Emulsion polymerization is used primarily for modacryhc compositions where a high level of a water-iasoluble monomer is used or where the monomer mixture is relatively slow reacting. 

Copolymerization is effected by suspension or emulsion techniques under such conditions that tetrafluoroethylene, but not ethylene, may homopolymerize. Bulk polymerization is not commercially feasible, because of heat-transfer limitations and explosion hazard of the comonomer mixture. Polymerizations typically take place below 100°C and 5 MPa (50 atm). Initiators include peroxides, redox systems (10), free-radical sources (11), and ionizing radiation (12). 

Technora. In 1985, Teijin Ltd. introduced Technora fiber, previously known as HM-50, into the high performance fiber market. Technora is based on the 1 1 copolyterephthalamide of 3,4 -diaminodiphenyl ether and/ -phenylenediamine (8). Technora is a whoUy aromatic copolyamide of PPT, modified with a crankshaft-shaped comonomer, which results in the formation of isotropic solutions that then become anisotropic during the shear alignment during spinning. The polymer is synthesized by the low temperature polymerization of/ -phenylenediamine, 3,4 -diaminophenyl ether, and terephthaloyl chloride in an amide solvent containing a small amount of an alkaU salt. Calcium chloride or lithium chloride is used as the alkaU salt. The solvents used are hexamethylphosphoramide (HMPA), A/-methyl-2-pyrrohdinone (NMP), and dimethyl acetamide (DMAc). The stmcture of Technora is as follows ... 

Cyclic ether and acetal polymerizations are also important commercially. Polymerization of tetrahydrofuran is used to produce polyether diol, and polyoxymethylene, an excellent engineering plastic, is obtained by the ring-opening polymerization of trioxane with a small amount of cycHc ether or acetal comonomer to prevent depolymerization (see Acetal resins Polyethers, tetrahydrofuran). 

With the avadabihty of polymerization catalysts, extensive efforts were devoted to developing economical processes for manufacture of isoprene. Several synthetic routes have been commercialized. With natural mbber as an alternative, the ultimate value of the polymer was more or less dictated by that market. The first commercial use of isoprene in the United States started in 1940. It was used as a minor comonomer with isobutylene for the preparation of butyl mbber. Polyisoprene was commercialized extensively in the 1960s (6). In the 1990s isoprene is used almost exclusively as a monomer for polymerization (see ELASTOLffiRS,SYNTHETic-POLYisoPRENE). 

Itaconic acid is a specialty monomer that affords performance advantages to certain polymeric coatings (qv) (see Polyesters, unsaturated). Emulsion stabihty, flow properties of the formulated coating, and adhesion to substrates are improved by the acid. Acrylonitrile fibers with low levels of the acid comonomer exhibit improved dye receptivity which allows mote efficient dyeing to deeper shades (see Acrylonitrile polymers Fibers, acrylic) (10,11). Itaconic acid has also been incorporated in PAN precursors of carbon and graphite fibers (qv) and into ethylene ionomers (qv) (12). 

Methyl Isopropenyl Ketone. Methyl isopropenyl ketone [814-78-8] (3-methyl-3-buten-2-one) is a colorless, lachrymatory Hquid, which like methyl vinyl ketone readily polymerizes on exposure to heat and light. Methyl isopropenyl ketone is produced by the condensation of methyl ethyl ketone and formaldehyde over an acid cation-exchange resin at 130°C and 1.5 MPa (218 psi) (274). Other methods are possible (275—280). Methyl isopropenyl ketone can be used as a comonomer which promotes photochemical degradation in polymeric materials. It is commercially available in North America (281). 

Density. The density (crystallinity) of catalyticaHy produced PE is primarily determined by the amount of comonomer ( a-olefin) in ethylene copolymer. This amount is easily controlled by varying the relative amounts of ethylene and the comonomer in a polymerization reactor. In contrast, the density of PE produced in free-radical processes is usually controlled by temperature. 

The Amoco reactor operates at 70—80°C and 2 MPa (300 psi) reactor pressure. The existence of several partially isolated compartments allows a semi-iadependent control of temperature as well as comonomer and hydrogen concentrations within each section, which ia turn offers a substantial control of the molecular weight and MWD of resias. Amoco technology also accommodates a large variety of polymerization catalysts, including Phillips and Ziegler catalysts. 

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