Packing material polystyrene

Polystyrene. There are two types of expandable polystyrene processes expandable polystyrene for molded articles and expandable polystyrene for loose-fill packing materials. 

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). 

A range of individual pore size PLgel packing materials is produced and their pore size distribution is conveniently represented by a SEC calibration curve as illustrated in Fig. 12.1. It should be pointed out that the descriptors used for the different pore sizes, 50 A, 100 A, and so on, are not the actual pore sizes of the beads but relate to the size of a polystyrene molecule just excluded from the packing material. This nomenclature comes from the original work carried out by Moore (3) and should only be viewed in the context of differentiating... 

The major advantage of the capillary hydrodynamic chromatography is that the mobile phase does not need to have similar solubility parameter as the sample and packing material. (In SEC, nonsize exclusion effects may be observed if the solubility parameter of the sample, packing material, or mobile phase is considerably different.) Therefore, the hydrodynamic size of polymers can be studied in a 0 solvent and even in a solvent that is not compatible with any currently available SEC packing material (9). Figure 22.4 is an example of polystyrene separation in both THF and diethyl malonate. Diethyl malonate is the 0 solvent of polystyrene at 31-36 C. 

Weathering in a tropical climate causes polyethylene containers to crack, polypropylene (PP) ropes to rupture, and ABS telephones to foil. Polystyrene (PS) and cellulose acetate films used as packing materials also fail due to weathering. 

Adamski, RP Anderson, JL, Configurational Effects on Polystyrene Rejection from Micro-porosou Membranes, Journal of Polymer Science Part B Polymer Physics 25, 765, 1987. Adler, PM, Porous Media, Geometry and Transports Butterworth-Heinemann Boston, 1992. Afeyan, NB Fulton, SP Regnier, FE, Perfusion Chromatography Packing Materials for Proteins and Peptides, Journal of Chromatography 544, 267, 1991. 

A variety of procedures were utilized to analyze this reaction mixture and to characterize a,10-diaminopolystyrene. Thin layer chromatographic analysis using toluene as eluent exhibited three spots with Rf values of 0.85, 0.09, and 0.05 which corresponded to polystyrene, poly(styryl)amine and a,w-diaminopolystyrene (see Figure 1). Pure samples of each of these products were obtained by silica gel column Chromatography of the crude reaction mixture initially using toluene as eluent [for polystyrene and poly(styryl)amine] followed by a methanol/toluene mixture (5/100 v/v) for the diamine. Size-exclusion chromatography could not be used to characterize the diamine since no peak was observed for this material, apparently because of the complication of physical adsorption to the column packing material. Therefore, the dibenzoyl derivative (eq. 5) was prepared and used for most of the analytical characterizations. 

When you hear polystyrene (PS) you probably think of products made of PS foam—disposable coffee cups, packing materials, buoys and boat bumpers, and cheap ice chests. As a matter of fact, PS foam products are so important that there s a special section at the end of this chapter... 

The heart of the instrumentaion is the fractionation column where the separation takes place. The most common packing material used has been a semi-rigid crosslinked polystyrene gel. Developments in column technology have made the low efficiency, large particle size (37-75P) packing material obsolete. 

In the first example, a broad distribution sample of polystyrene was analyzed on a set of high efficiency Ultrastyragel GPC columns (lO. lO jlO A) with which It was determined that Mw = 214,000 and Mn = 87,000. In the Ideal case, a similar set of three (10, 10, lO A) preparative Styragel columns (each 57 mm I.D. X 4 ft) could have been used to fractionate the polystyrene sample. However, we Initially chose to demonstrate the extent of fractionation possible with only one preparative column and selected the lO A column packing material so as not to exclude any of the higher molecular weight fractions. 

Yang, Y.B., Regnier, F.E. (1991). Coated hydrophilic polystyrene-based packing materials. J. Chromatogr., 544(1-2), 233-247. 

Figure 12.29 shows that using styrene as the monomer yields polystyrene. Transparent plastic cups are made of polystyrene, as are thousands of other household items. Blowing gas into liquid polystyrene generates Styrofoam, widely used for coffee cups, packing material, and insulation. 

Packing materials in columns of various lengths include silica gel. alumina, glass beads, polystyrene gel, and ion exchange resins. 

GPC is a further special form of liquid chromatography. The separation column is packed with porous, polymer gels (e.g. polystyrene gel) as stationary phase. The particle size of the packing material and the size distribution of the pores are well defined and uniform. In GPC molecules are separated according to their effective size in solution, i.e., their hydrodynamic volume, and not according to their affinity for the support material. 

Although the problem has become less severe due to the trend towards reducing residual monomer content in materials there is still potential for taint problems to occur in products. Total styrene content in current materials varies within a range of 250 to 350 ppm (even for laminate materials). Of the commonly polystyrene containing portion pack materials mono-material PS has the greatest migration followed by PS/PE and the material with the lowest migration is from PS/EVOH/PE. 

Styrene can cause off-flavors in food products packed in polystyrene packaging materials. Each food product has a different sensitivity to styrene off-flavors and thus each food package system needs to be evaluated individually. The formation of styrene off-flavor in a given package/product system can be estimated a priori given the styrene threshold concentration in the food, the initial residual styrene monomer concentration in the packaging material and the desired shelf life. If this information is not readily available then accelerated storage tests followed by a sensory comparison can be carried out to evaluate the potential of off-flavor formation in the product. 

United States alone, 5 x 109 kg of plastic resins (typically used in packaging and transportation) are produced every year. Disposable goods and packing material represent about one-third of the total plastic production and have the largest environmental impact. More than 90% of the plastic material in municipal waste consists of polyethylene, polyvinyl chloride, and polystyrene, which are all resistant to biodegradation (see Table 9.1). 

Another important parameter is the ability of the column to discriminate different ranges of molecular masses. This range is dependent on the size of the pores of packing material and pore size distribution. Column manufacturers usually provide the standard calibration curves of polystyrene standards in TFIF for each column, as shown in Figure 6-6 [8]. 

In addition to the silica-based, reversed-phase particles, polymeric particles are available that utilize a hydrophobic stationary phase, e.g., cross-linked polystyrene divinylbenzene. In these polymeric stationary phases, the backbone of the particle provides the opportunity for hydrophobic interactions. Although these packing materials are available in high-performance particles, the particles cannot withstand the high pressure that silica particles can and thus are typically used in medium- to low-pressure operations. The polymeric stationary phases usually have a series of aromatic... 

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