Styrene polymer, properties

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

Rubber-Modified Copolymers. Acrylonitrile—butadiene—styrene polymers have become important commercial products since the mid-1950s. The development and properties of ABS polymers have been discussed in detail (76) (see Acrylonitrile polymers). ABS polymers, like HIPS, are two-phase systems in which the elastomer component is dispersed in the rigid SAN copolymer matrix. The electron photomicrographs in Figure 6 show the difference in morphology of mass vs emulsion ABS polymers. The differences in stmcture of the dispersed phases are primarily a result of differences in production processes, types of mbber used, and variation in mbber concentrations. 

Whereas random copolymers exhibit one T described by equation 38, block copolymers, because of this microphase separation, exhibit two glass-transition temperatures. The T of each block is close to, if not the same as, the homopolymer from which it was formed. Polymer properties are also affected by the arrangement of the blocks. This is shown for high styrene-containing or high molecular-weight styrene resias of various block arrangements ia Table 3. 

The effect of media viscosity on polymerization rates and polymer properties is well known. Analysis of kinetic rate data generally is constrained to propagation rate constant invarient of media viscosity. The current research developes an experimental design that allows for the evaluation of viscosity dependence on uncoupled rate constants including initiation, propagation and macromolecular association. The system styrene, toluene n-butyllithium is utilized. 

The Instantaneous values for the initiator efficiencies and the rate constants associated with the suspension polymerization of styrene using benzoyl peroxide have been determined from explicit equations based on the instantaneous polymer properties. The explicit equations for the rate parameters have been derived based on accepted reaction schemes and the standard kinetic assumptions (SSH and LCA). The instantaneous polymer properties have been obtained from the cummulative experimental values by proposing empirical models for the instantaneous properties and then fitting them to the cummulative experimental values. This has circumvented some of the problems associated with differenciating experimental data. The results obtained show that ... 

Hivalloy A process for grafting styrenic polymers on to polyolefines, using a Ziegler-Natta catalyst. The products combine the physical properties of both polymer types. Developed by Montell and commercialized in the United States in 1997. See also Catalloy. Oxley, D. F., Chem. Ind. (London), 1998, (8), 307. 

Meincke O, Kaempfer D, Weickmann H, Friedrich C, Vathauer M, Warth H (2004). Mechanical properties and electrical conductivity of carbon-nanotube filled polyamide-6 and its blends with acrylonitrile/butadiene/styrene. Polymer 45 739-748. 

The deliberate introduction of multifunctional branching into anionically prepared polydiene and poly (diene-co-styrene) polymers produces materials with unique morphological and viscoelastic properties (1-3). Work has included synthesis of symmetric star polymers produced by reaction of living polyanionic "arms" with multi-functional chlorosilane (4-9),... 

Aromatic electrophilic substitution is used commercially to produce styrene polymers with ion-exchange properties by the incorporation of sulfonic acid or quaternary ammonium groups [Brydson, 1999 Lucas et al., 1980 Miller et al., 1963]. Crosslinked styrene-divinyl-benzene copolymers are used as the starting polymer to obtain insoluble final products, usually in the form of beads and also membranes. The use of polystyrene itself would yield soluble ion-exchange products. An anion-exchange product is obtained by chloromethylation followed by reaction with a tertiary amine (Eq. 9-38) while sulfonation yields a cation-exchange product (Eq. 9-39) ... 

An outstanding property of these polymers is their shear stability. The sonic shear stability testsfci indicate that these polymers are superior to some of the currently used polymers of ethylene-propylene or methacrylate type. The excellent stability of the hydrogenated diene-styrene polymers is attributed to their relatively low molecular weight and narrow distribution consistent with the established theory of shear degradation of polymers. The most recent developments in this field are block polymer VI improvers with dispersancy properties, built into the molecule by chemical modification of the rubber block. 2... 

Since ABS is composed of a hard material and a soft material, it combines the rigidity of acrylonitrile and styrene polymers with the toughness of butadiene rubbers. Most advantageous is its impact resistance and toughness. ABS can be tailored to improve the impact resistance, toughness, and heat resistance. Selected properties of an ABS type are shown in Table 8.8. 

Osaki, K., SchragJ.L. Viscoelastic properties of polymer solutions in high-viscosity solvents and limiting high-frequency behavior. I. Polystyrene and poly(a-methyl-styrene). Polymer J. (Japan) 2,541-549 (1971). 

Weldons, J. D., and V. Stannett Some properties of isolated graft copolymers of cellulose acetate and styrene. Polymer preprint A.C.S. Meeting, Detroit, Michigan April 1965. 

Chemical Safety Data Document, Chemical Safety Data SD-37, Properties and Essential Information for Safe Handling and Use of Styrene Polymer, Manufacturing Chemists Association, Inc., Washington, DC, 1971. 

In order to prepare non-styrenic polymer-supported organotin chlorides, which are expected to show physical properties such as mechanical strength, polarity and porosity different from those of polystyrene-based supports, Deleuze and coworkers copolymerised dibutyl[3-(allyloxy)propyl]tin chloride with N-phenylmaleimide (PMI) and l,l/-(methylene-4,l-phenylene)bismaleimide (MPBMI) to prepare the polymers 88a and 88b180. 

The decorative laminates described in the previous chapter are made with selected thermosetting resins while resins of this type can be moulded and extruded by methods similar to those outlined in the present and the next chapter the materials employed for these processes predominantly are thermoplastic. Many such plastics can be moulded and extruded under suitable conditions, the most important in terms of quantities used being those that combine properties satisfactory for the purpose with convenience in pro-cessing-especially the polyolefins (polyethylene and polypropylene), poly(vinyl chloride), and styrene polymers and blends. Other plastics with special qualities, such as better resistance to chemical attack, heat, impact, and wear, also are used—including acetals (polyformaldehyde or polyoxymethylene), polyamides, polycarbonates, thermoplastic polyesters like poly(ethylene terephtha-late) and poly(butylene terephthalate), and modified poly(phenylene oxide),... 

Revilla, J., Delair, T., Pichot, C. and Gallot, B. (1995) Preparation and properties of comb-like polymers obtained by radical homo- and copolymerization of a liposaccharidic monomer with styrene. Polymer, 37, 687-98. 

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