Polystyrene and related polymers

When polystyrene films are exposed to ultraviolet radiation of 235.7 nm in vacuo, crosslinking occurs and the sample becomes partly insoluble [41]. Grassie and Weir [42] have performed a detailed investigation of the photolysis of polystyrene in vacuo as a preliminary step to the study of the photo-oxidation of that polymer. They found that the only gaseous product formed is hydrogen with a quantum yield of 4.3 x 10 2. The rate of the reaction increases linearly with the intensity of the incident light 

Vacuum irradiation of polystyrene is accompanied by a yellowish discolouration of the polymer [41, 44], which develops at a comparable rate under 235.7 nm radiation whether or not oxygen is present. Colouration is thus not a manifestation of oxidation [44]. The optical 

The photolysis of poly-a-methylstyrene, both in solution [46] and as solid films [10], has been studied by Fox and coworkers. For solid films, a rapid drop in the molecular weight has been observed. The quantum yield of this process is 1 x 10-3 at 27°C and 2 x 10-2 at 115°C. Simultaneously, monomer is evolved with quantum yields of 7 x 10 3 and 5 x 10 1 at 27 and 115°C, respectively. Such behaviour has been ascribed to random breaking of the main chain followed by depolymerization [10] namely, 

It seems doubtful, however, that scission of a C—C bond of the polymer backbone could occur as a primary photochemical process. A more recent 

ESR investigation indicates that the radical resulting from scission of the methyl side group is formed on irradiation of a highly concentrated glassy solution of poly-a-methylstyrene [43]. One can thus conclude that the following reactions are more likely to occur as the initial steps of the photodegradation of poly-a-methylstyrene  

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Radicals and Charge Transfer Radical Complexes of Polystyrene and Related Polymers... 

Polystyrene and related polymers have most extensively been studied in organic solutions in connection with the radiation-induced degradation [57, 58, 64]. In... 

Bucknall and Smith (17) concluded that crazing is the dominant mechanism to toughen high impact polystyrene and related polymers. One important function of the rubber particles is to serve as craze initiators and stabilizers in the glassy matrix. However Newman and Strella (18) concluded from optical microscope studies that cold drawing is responsible for toughness in ABS. 

Although there have been many H- and C-studies on polystyrene and related polymers, present understanding of the spectra obtained is rather unsatisfactory. We will confine our discussion here to polystyrene and related polymers prepared by free radical initiated polymerization. The H-spectr im of polystyrene is not rich in detail. The resonance of aromatic protons is observed in two areas, the ortho protons being observed upfield from the meta and para protons. In the 300 MHz spectr am of polystyrene or in the 100 MHz spectrum of poly(3,4,5-trideuterio-styrene) [69], the ortho proton resonance is observed in three areas (relative intensities 9/6/1). Although... 

It is interesting that the pmr and cmr spectra of poly(a-methylstyrene) can be interpreted without apparent complication [87-88]. Much additional work needs to be done on polystyrene and related polymers before a clear understanding of their spectra and structure emerges, however. 

Sanz, A., Ruppel, M., Douglas, J.F., and Cabral, J.T. (2008) Plasticization effect of C-60 on the fast dynamics of polystyrene and related polymers an incoherent neutron scattering study. Journal of Physics Condensed Matter, 20 (10), 104209. 

Whilst it is inevitable that polypropylene will be compared more frequently with polyethylene than with any other polymer its use as an injection moulding material also necessitates comparison with polystyrene and related products, cellulose acetate and cellulose acetate-butyrate, each of which has a similar rigidity. When comparisons are made it is also necessary to distinguish between conventional homopolymers and the block copolymers. A somewhat crude comparison between these different polymers is attempted in Table 11.7 but further details should be sought out from the appropriate chapters dealing with the other materials. 

Radiation-induced Degradation.—There have been several reports on radiation effects in polymers,288 including single crystals,287 fluoropolymers,288 polyamides,289 polysiloxanes,270 polyethylene and its copolymers,271 polypropylene,272 polyolefins,273 polystyrene and its copolymers,274 poly(vinyl chloride) and related polymers,275 rubbers,278 polysulphones and other sulphur-containing polymers,277 polycarbonate,278 nylon,279 poly(vinylpyridines),280 and wool.281... 

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. 

Polystyrene and closely related thermoplasties such as the ABS polymers may be proeessed by sueh techniques as injection moulding, extrusion and blow moulding. Of less importance is the processing in latex and solution form and the... 

There are a large number of literature references that refer the use of SPE cartridges for the extraction of pesticides from water. There are several comprehensive reviews of the use of SPE, including that by Soriano et al. who discussed the advantages and limitations of a number of sorbents for the analysis of carbamates. Hennion reviewed the properties and uses of carbon based materials for extraction of a wide multiclass range of pesticides. Thorstensen et al. described the use of a high-capacity cross-linked polystyrene-based polymer for the SPE of phenoxy acids and bentazone, and Tanabe et al reported the use of a styrene-divinylbenzene copolymer for the determination of 90 pesticides and related compounds in river water. SPE cartridges are also widely used for the cleanup of solvent extracts, as described below. 

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