Polystyrene gel

Water is softened by removing calcium and magnesium ions from hard water in exchange for sodium ions at sites on cation-exchange resin. Water softeners typically use a gel polystyrene sulfonate cation-exchange resin regenerated with a 10% salt brine solution (25). 

One component of the eluent should have properties similar to those of the analytes, and this solvent is diluted by another solvent to control the retention time. The basic idea can be understood from the chromatographic behaviour of phthalic acid esters and polycyclic aromatic hydrocarbons (PAH). This approach can be applied to the separation procedure for a variety of stationary phase materials, including silica gel, polystyrene gel, and ion-exchangers. 

Table 4. Reduced axial transport rate v. at different temperatures and rate constant ks of spontaneous polymer diffusion from sol into gel. (Polystyrene with different weight average degrees of polymerization Pw)...

High Performance Size Exclusion Chromatography. The Hewlett-Packard 1090 liquid chromatograph was used with the HP 1040 diode array or HP 1037A refractive index (and HP 3392 integrator) detectors. A fifty A (5 mm, 300 x 7 mm) Polymer Laboratories PL gel (polystyrene-divinylbenzene copolymer gel) column was used and standards were as described in Chum et al. (13). Tetrahydrofuran solutions of oil and oil fractions were analyzed. 

The use of normal phase silica columns was also described but after acetylation of the flavonoids and then isocratic elution on silica gel. Polystyrene divinylben-zene as a stationary phase was also found to give satisfactory separation and good peak shapes without using... 

Solid-Supported Surface Catalysis by Metal Complexes. Hong et al. (1987a, b, in press) have prepared a variety of hybrid catalysts between Co(II) phthalocyanine complexes and the surfaces of silica gel, polystyrene-divinylben-zene, and Ti02 and tested these hybrids for catalytic activity with respect to the autoxidation of hydrogen sulfide, sulfur dioxide, 2-mercaptoethanol, cysteine, and hydrazine ... 

Similar studies of application of anion exchangers Amberlite IRA-900 (macroporous, polystyrene, strongly basic anion exchanger of type 1, 16-50 mesh) [133-135] and Amberlite IRA-410 (gel, polystyrene, strongly basic of type 2,16-50 mesh) [135] for recovery and removal of trace amounts of Pd(II), Pt(II), Ru(III), Rh(III), Au(III) and Ir(IV) ions from chloride and radioactive nitrate waste waters were carried out by the Els et al. [133, 134] and El-Said et al. 

DF 0.09, 10% cross-linked gel polystyrene, the enolate generated with triphenyl-methylUthium at room temperature and trapped as soon as the red color of Ae base faded, gave 94-97% GC yields from acylation with p-nitrobenzoyl chloride or acetyl chloride and from alkylation with 1-bromobutane or benzyl bromide. Isolated yields were 73-87% on a 16-34 mmol scale, and 77% in one example on a 100 mmol scale (175 g of dry polymeric reagent). TTie polymer was recycled with no decrease in acylation yield. The analogous benzyl ester in solution gave 59% self[Pg.273]

The most common stationary phases used for the separation of different classes of phenolics are silica gel, Sep-Pak C18, Toyopearl HW-40, Polyamide gel. Polystyrene resin, Fractogel TSK, Biogel P-2, Polyamide, Amberhte, and Sephadex LH-20 [57-64]. 

Fig. 7 The swelling behavior of a dry gel (polystyrene resin that is cross-linked by divinyl benzene) when it is immersed in various halogenated solvents [23].

Two classes of micron-sized stationary phases have been encountered in this section silica particles and cross-linked polymer resin beads. Both materials are porous, with pore sizes ranging from approximately 50 to 4000 A for silica particles and from 50 to 1,000,000 A for divinylbenzene cross-linked polystyrene resins. In size-exclusion chromatography, also called molecular-exclusion or gel-permeation chromatography, separation is based on the solute s ability to enter into the pores of the column packing. Smaller solutes spend proportionally more time within the pores and, consequently, take longer to elute from the column. 

Both preparative and analytical GPC were employed to analyze a standard (NBS 706) polystyrene sample. Fractions were collected from the preparative column, the solvent was evaporated away, and the weight of each polymer fraction was obtained. The molecular weights of each fraction were obtained usmg an analytical gel permeation chromatograph calibrated in terms of both and M. The following data were obtained ... 

Cross-linked macromolecular gels have been prepared by Eriedel-Crafts cross-linking of polystyrene with a dihaloaromatic compound, or Eriedel-Crafts cross-linking of styrene—chloroalkyl styrene copolymers. These polymers in their sulfonated form have found use as thermal stabilizers, especially for use in drilling fluids (193). Cross-linking polymers with good heat resistance were also prepared by Eriedel-Crafts reaction of diacid haUdes with haloaryl ethers (194). 

MFI = melt flow index IV = intrinsic viscosity in CH2CI2 at 25°C From gel-permeation chromatography using polystyrene standards. 

Requirements for heat- and cold-curing denture-base resins prepared from powder—liquids, gels, preopolymerized blanks, and fluid resins composed of acryflc, vinyl, and polystyrene polymers are given in ANSI/ADA specification no. 12 for denture-base polymers. 

In the present work it was studied the dependence of analytical characteristics of the composite SG - polyelectrolyte films obtained by sol-gel technique on the content of non-ionic surfactant in initial sol. Triton X-100 and Tween 20 were examined as surfactants polystyrene sulfonate (PSS), polyvinyl-sulfonic acid (PVSA) or polydimethyl-ammonium chloride (PDMDA) were used as polyelectrolytes. The final films were applied as modificators of glass slides and pyrolytic graphite (PG) electrode surfaces. 

The presence of a COOH functionality on a polystyrene resin can be detected using a 0.25% solution of malachite green-oxalate in ethanol in the presence of a drop of triethylamine. Beads with COOH functionalities are coloured dark green or appear as clear gel beads [Attardi, Porcu and Taddei Tetrahedron Lett 41 7391 2000]. 

The use of stabilisers (antioxidants) may, however, have adverse effects in that they inhibit cross-linking of the rubber. The influence of phenolic antioxidants on polystyrene-SBR alloys blended in an internal mixer at 180°C has been studied. It was found that alloys containing 1% of certain phenolic antioxidants were gel-deficient in the rubber phase.The gel-deficient blends were blotchy in appearance, and had lower flow rates compared with the normal materials, and mouldings were somewhat brittle. Substantial improvements in the impact properties were achieved when the antioxidant was added later in the mixing cycle after the rubber had reached a moderate degree of cross-linking. 

Ion Exchange Resins - Spectra/Gel Ion Exchange resins are ion exchange media for use in low-pressure liquid chromatography. They are based on a polystyrene/divinylbenzene support and are available for both anion and cation exchange applications. This site will give you a reasonable... 

N. A. Rotstein, T. P. Lodge. Tracer diffusion of linear polystyrenes in poly-(vinyl methyl ether) gels. Macromolecules 25.T 316-1325, 1992. 

A porous polystyrene-divinylbenzene gel is produced by suspension polymerization in an aqueous system with incorporation of more than 5 mol% initiator to a total amount of styrene and divinylbenzene with an inert organic solvent as diluent and porogen (24). 

A novel cross-linked polystyrene-divinylbenzene copolymer has been produced from suspension polymerization with toluene as a diluent, having an average particle size of 2 to 50 /rm, with an exclusive molecular weight for the polystyrene standard from about 500 to 20,000 in gel-permeation chromatography. A process for preparing the PS-DVB copolymer by suspension polymerization in the presence of at least one free-radical polymerization initiator, such as 2,2 -azo-bis (2,4-dimethylvaleronitrile) with a half-life of about 2 to 60 min at 70°C, has been disclosed (78). 

The packing material for liquid chromatography is produced from styrene and divinylbenzene dissolved in 50 to 300% by weight of organic solvent to both monomers. The constitution of divinylbenzene in the monomer mixture is not less than 60% by weight. In gel-permeation chromatography, the exclusive molecular weight is not less than 1 X 10 in terms of standard polystyrene (79). 

Size exclusion was first noted in the late fifties when separations of proteins on columns packed with swollen maize starch were observed (Lindqvist and Storgards, 1955 Lathe and Ruthven, 1956). The run time was typically 48 hr. With the advent of a commercial material for size separation of molecules, a gel of cross-linked dextran, researchers were given a purposely made material for size exclusion, or gel filtration, of solutes as described in the classical work by Porath and Flodin (1959). The material, named Sephadex, was made available commercially by Pharmacia in 1959. This promoted a rapid development of the technique and it was soon applied to the separation of proteins and aqueous polymers. The work by Porath and Flodin promoted Moore (1964) to apply the technique to size separation, gel permeation chromatography of organic molecules on gels of lightly cross-linked polystyrene (i.e., Styragel). 

Modern SEC columns are packed with material other than polystyrene gels, such as porous silica particles or highly cross-linked styrene-divinylbenzene copolymers. Because of improvements in speed and resolution, the term SEC is sometimes replaced by the term high-performance size-exclusion chromatography (HPSEC). 

FIGURE 4.38 Calibration curves for TSK-GEL Hxl columns with polyst/rene standards. Column TSK-GEL Hxl series, two 7.8 mm x 30 cm columns in series. Sample Polystyrene standards. Elution Tetrahydrofuran. Flow rate 1.0 ml/min. Detection Rl. 

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