Solid polystyrene

Chen, C.-C., Continuous production of solid polystyrene in back-mixed and linear-flow reactors, Polym. Eng. Sci., 40, 441-464 (2000). 

For the above-mentioned reasons the performance of this procedure is not quite simple in the context of a practical course.Therefore the following instruction is intended only to experimentally demonstrate two effects dissolving of pentane in solid polystyrene and foaming of the polystyrene, containing a blowing agent, in hot water. 

To expedite peptide syntheses of up to 124 amino acid units, beads of solid polystyrene— with chloromethyl groups, —CH CI, para to about every hundredth phenyl group—are used in an automated process. The sequence of steps is (1) attach C-terminal Boc-protected amino acid by... 

Foams have limited use for these purposes. Rigid cellular PVC is good as a thermal barrier but not for structural parts. Doors and frames of structural molded foam, eg, foamed high impact polystyrene, can be made by injection molding, with recesses for hinges, striker plates, and miter corners. Solid polystyrene and structural foam-molded polyurethane have been molded for door frames. 

Figure 11.2. Rates of desorption of gases from polystyrene pellets and granules. Samples of solid polystyrene were saturated with gas at high pressure prior to measurement. The sample weights are measured continuously as gas desorbs from the sample at room temperature and atmospheric pressure. The label pellets refers to the 1/8 in x 1/8 in diameter polystyrene pellets received from the manufacturer, while granules refers to pellets ground to approximately 14 mesh size. Data from Kwag (1998).

Bachmann and Seebach [159] have reported the preparation and characterization of cyclic lactones (MeCHCH2C(0)0)n, where n = 4 and 8. The reaction product between butyl lithium in benzene and the solid polystyrene support PS-C6H4CH2NH2 leads to a lithiated species that can be represented as PS-Cfd bCI 12N11 Li(BuI i)x, where x 4 is active in the ring-opening of the cyclic esters L-lactide, rac-lactide, and 2,5-morpholinediones, leading to their respective cyclic oligoesters and cyclodepsipeptides (Fig. 49) [160]. The... 

A liquid preparation with solid polystyrene (0.6 g) dissolved in liquid styrene monomer (1.5 mL) was cast against a mold. Polymerization was accomplished with UV irradiation (21°C, 18 h). Solid PS was included to reduce the degree of shrinkage that occurred when monomeric styrene was photopolymerized [85]. In a similar manner, PMMA dissolved in MMA was cast against a Si master. Upon UV polymerization (with BME as the photoinitiator), a PMMA chip is formed. Nearly 100 PMMA chips can be replicated using a single Si master [223]. 

The present paper reviews the application of ion beams with energy above 10 keV to polymers and describes our recent work on the radiation effects of ion beams on solid polystyrene films studied by solubility change and time-resolved spectroscopy. 

Results from the initial resin studied are also being employed in the development of additional experimental procedures. Plans are currently being drafted to prepare three-ply test specimens that are similar to the specimens used in the initial study, with the middle ply consisting of solid polystyrene. Comparing specimens with and without the graft polymers introduced to the ply interfaces should provide additional information on the ability of the cellulosic graft polymers to facilitate bonding between wood and plastic materials. If this approach proves successful, additional procedures will then be developed for the production of simple composite specimens. 

Figure 1.4. Raman scattering, IR transmission, and NIR transmission spectra of polystyrene, plotted on a single energy scale. Intensity scales are very different, with NIR absorption being much weaker than IR absorption. In this case, the sample concentrations for NIR and Raman (solid polystyrene) were much greater than that for FTIR (dilute powder in KBr).

Fig. 14 Schematic representation of a spherical polyelectrolyte brush prepared by the photoemulsion grafting from technique (details see text). The brush consists of a solid polystyrene core and surface-attached strong (PSS) or weak (PAA) polyelectrolyte brush shell (Reprinted from Ref. [71] with permission from the American Physical Society)...

The NCS-results from benzene, see Fig. 6, reveal the following effect the basic Eq. (2) is strongly violated the measured ratio Ah/Ac is ca. 25% lower than its conventionally expected value (numerical values of cross-sections, cf. related textbooks). Also this observation contradicts every conventional expectation. The same anomalous effect has been also found in solid polystyrene and various partially deuterated polystyrene samples [Chatzidimitriou-Dreismann 2002 (a)]. 

The emission spectrum of solid polystyrene at room temperature has already been shown in Figure 1. It shows a broad excimer emission at 325 nm and only a trace of monomer-like emission. The excimer and... 

It is clear from our results that the initial excitation in solid polystyrene must be extremely mobile in contrast to the case of the polymer in solution. However, it is now clear that available experimental results do not directly examine the mobile excitation. In particular, observed "monomer-like" emission is due to a shallow trap, which vitiates a previous analysis (Id,18) that assumed it to be due to the mobile excitation. Direct determination of mobile excitation dynamics will require extension of photophysical measurements to the picosecond time regime and efforts by us to accomplish this goal are now in progress. 

Most of the papers in this section are concerned with photo-oxidation reactions, but a few papers refer to photochemical reactions in polymer matrices. Thus the kinetics of the photo-oxidation of anthracene and naphthacene in solid polystyrene (PS),170 the photoionization of aromatic hydrocarbons dissolved in PMMA and PS,171 the photoreactions of naphthalene in cellulose triacetate,172 the cis-trans isomerization of stilbene residues in the side-chains of polymers,173 intrachain photodimerization in polymers,174 photoisomerization of 1,2-diphenyl-cyclopropane by peptides containing naphthalene in a side-chain,176 and photochemical transformations of poly(vinyl p-azidobenzoate)176 have been reported. 

Time resolved spectroscopy has developed assignments of intermediate species in radiation chemistry as revealed in the other sections. However, because solid polymers are less transparent, the works obtained so far seem to be limited mainly to polymer solution systems or liquid model-compounds. The lifetime of intermediates depends on LET the fluorescence lifetime of n-dodecane is shorter for higher LET radiation [83], which was studied as liquid model compounds for polyethylene. The observation is attributed to scavenging upon encountering of intermediates. Light emission from excimers of solid polystyrene has constant lifetime irrespective to LET [84], whereas polystyrene... 

It is interesting to note that in many cases the efficiency of radical reactions in solid glassy polymers appears to be unaffected by the polymer matrix. In the case of type-I reactions in solid polystyrene we have observed that the efficiency of radical escape when at least one of the radicals is a small molecule is similar in polymeric glasses to that observed in solution. One can deduce from this that polymeric glasses are not particularly good at trapping radical species unless they are cooled to very low temperatures. 

A standard preparation of polystyrene, prepared by the Dow Chemical Company, has been distributed by P. Debye and A. M. Bueche of Cornell University to many workers in the United States. The solid polystyrene is dissolved in toluene (5 g./l.) the solution is not very stable, and must be made up afresh at frequent intervals. Values for the turbidity (or reduced intensity) of this standard solution have been determined in several laboratories for results, see Brice, Halwer and Speiser (1950), Table VI also Edsall, Edelhoch, Lontie and Morrison (1950). 

Fig. 13. Removal of the contribution caused by density fluctuations of the solid polystyrene [85, S6].Empty circles Desmeared scattering intensity the marked range shows the q-range used for the fit of filled circles scattering intensity after subtraction of...

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