Styrene-containing

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. 

Random copolymers of acrylonitrile and styrene containing less than 30% AN have been well known (11), and many varieties have been sold commercially. The generic material known as SAN, which is a copolymer of 25% AN and 75% styrene, has been sold for many years but has not been used in food or beverage packaging because of its relatively poor barrier and organoleptic properties. There was little or no interest in... 

On land, too, there are changes in the way plastics are disposed of. In the UK some local authorities are actively promoting recycling of plastic bottles and poly(styrene) containers, for example by schemes where local residents place recyclable materials in designated boxes for refuse collectors. These boxes are taken to a Materials Reclamation Facility for final sorting of the plastics waste. 

The other main support used for solid base catalysts is polystyrene, which while it does not have a well-defined porous structure, does swell in solvents providing an accessible high surface area on which to carry out reactions. One common method of chemically attaching groups to polystyrene involves incorporation of specific amounts of styrene contain-... 

There are three principal families of styrene containing polymers, which are used to make commercial plastic products. The first family is pure polystyrene, the second family comprises random copolymers, and the final family consists of polystyrene chains grafted to blocks of rubbery polymers. There are also synthetic rubbers that contain significant concentrations of styrene, but these are outside the scope of this book. 

Styrene-containing polymer is completely soluble in common solvents such as CHCI3, THF, xylene, or chlorobenzene and can be spin cast as thin films that are easily cross-linked... 

In developing his theory of the polymerisations by ionising radiations Plesch now distinguishes between the mono-alkenes and other monomers, thus if a monomer, such as styrene, contains two donor groups, then both of these can be involved in the complex formation with the carbenium ion, but only the Jt-complex involving the double-bond can propagate. This means that Equation (40) must be replaced by... 

Since the rate-constants calculated by Kunitake and Takarabe for styrene contain unknown contributions from at least three propagators, they cannot be included in our final table of results. It is also evident that the variation of the rate-constants with temperature cannot provide any useful information, because the relative contributions from the different propagators change with temperature. 

P.Y.110 lends color to polystyrene and styrene containing plastics. It is a suitable candidate for unsaturated polyester and other cast resins, as well as for polyurethane. P.Y.110 is used to an appreciable extent in polypropylene spin dyeing, it is very lightfast in this medium. It is utilized in polyacrylonitrile spin dyeing and sometimes also in polyamide. Its fastness properties, however, especially its lightfastness, do not meet special application conditions (Sec. 1.8.3.8). 

In order to synthesize the IPN, the urethane elastomer was swelled with styrene containing 0.4% benzoin as initiator and 1% divinyl benzene (DVB) as crosslinker. Polymerization of the styrene was carried out by ultraviolet radiation at room temperature for 24 hours. 

Styrene is a commercially important monomer that is used extensively in the manufacture of polystyrene resins and in co-polymers with acrylonitrile and 1,3-butadiene (reinforced plastics). Exposure to styrene occurs due to intake of food that has been in contact with styrene-containing polymers. lARC has determined that styrene is possibly carcinogenic to humans. There is no restriction on using styrene within the European Union (i.e., there is no SML). 

Note Normally inhibited with 8-12 ppm 4-7er7-butylcatechol to prevent polymerization. According to Chevron Phillips Company (March 2002), 99.93% styrene contains the following components (ppm) benzene (<1), toluene (<1), ethylbenzene (50), a-meth ylstyrene (175), m + p-xylene (120), o-xylene (125), isopropylbenzene (100), / -propylbenzene (60), m + p-ethyltoluene (20), vinyltoluene (10), phenylacetylene (50), m + p-divinylbenzene (<10), o-divinylbenzene (<5), aldehydes as benzaldehyde (15), and peroxides as benzoyl-peroxides (5). 

Similar results were obtained by shear blending of two synthetic elastomers (45). The formation of a block or graft copolymer during the process of mixing butadiene rubber (SKB) and styrene-containing rubber (SKS-30A) was postulated by Slonimskii and Reztsova (49). They claimed that the anomalies observed in the dependences on composition of the mechanical properties of a mixture of two mutually insoluble rubbers after vulcanization may be reduced by increasing the part played by the mechanical mixing (inert atmosphere, reduction of radical acceptors, intensity of mechanical action). 

The correct alignment of surfactants in some, but not all, SUVs is an essential requirement for polymerization. Polymerization of diacetylenes is topochemically controlled and only occurs below the phase transition temperature of the surfactant. In contrast, SUVs prepared from styrene-containing surfactants could be polymerized in their fluid states [55]. The degree of polymerization varied from very low (10-20 for SUVs prepared from styrene containing surfactants) to rather high (several hundred for SUVs prepared from diacetylene-containing surfactants). 

Polymer mixtures of aromatic PC, ABS graft polymer and styrene-containing copolymers and monophosphates are described as flameproofing additives (20). It has been claimed that phosphonate amines are superior flame retardants for PC/ABS molding compositions (21). 

Styrene and alphamethylstyrene have been polymerized with a number of different catalyts. Phillips, Hanlon and Tobolsky (38) found that low-styrene content copolymers are obtained with cationic Friedel-Crafts type catalysts while high styrene containing copolymers are obtained with anionic catalysts. Aluminum bromide or BFS etherate... 

If the polymer absorbs at a wavelength where both solvent and precipitant are transparent, HPPLC can be performed with the help of a UV detector. Styrene-containing copolymers can be analyzed with alkane hydrocarbon/THF eluents at around 254 nm. In order to gain high sensitivity in gradient elution, we removed the stabilizer from the THF by distillation under N2 123). Caution is required with respect to peroxides. 

Preliminary experiments were performed to study the (electroactive) behaviour of styrene containing TRAP at a platinum ultramicro disc electrode, which was obtained as described in Chapter 1, pages 21-24. However, in the range where copper activity is observed (see later) no additional reactions of the solvent or the electrolyte were observed. Outside this potential window, oxidation of styrene and reduction of the electrolyte were observed. As these potential ranges are not interesting for the purpose of detection of Cu(II) and Cu(I), they are not further described in this chapter. 

Styrene contains a benzene ring and will be appreciably stabilized by resonance, which makes it lower in energy than cyclooctatetraene. 

The development of the triad fractions as observed by NMR during the course of a polymerization of a 75/25 ethyl acrylate styrene copolymer is shown in Figure 10. Over the course of the feed, the ethyl acrylate content dropped from 100% to 50% linearly. The increase in styrene containing triads is evident from the NMR spectra and is predicted by the model. Figure 11 shows the correspondence between calculated and measured triad fractions for this system. 

As another example, let s consider the chemical reactions that are used to prepare ion exchange resins. These resins are composed of small polymer beads that can be used to exchange one ion for another in aqueous solutions. The polymer that is used in these applications is a cross-linked polystyrene. To make this material, styrene containing a small amount of divinylbenzene is polymerized. Each vinyl group of divinylbenzene can become part of a separate polymer chain, so these groups act as cross-links between chains. The resulting polymer is used in the form of small beads that are completely insoluble in typical solvents. 

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