Polymer Laboratories

With large companies such as Waters Corp., TOSOH Corp., Polymer Laboratories Ltd., Shodex Corp., and Phenomenex Inc. and smaller companies such as American Polymer Standards Corp., Polymer Standards Service, and Jordi Associates, all manufacturing ST-DVB GPC/SEC gel, the market has become saturated with analogous columns. All the manufacturers just men-... 

SIZE EXCLUSION CHROMATOGRAPHY COLUMNS FROM POLYMER LABORATORIES... 

For organic SEC separations the use of polystyrene/divinylbenzene (PS/ DVB) particles is almost universal throughout the industry. Polymer Laboratories PS/DVB material, PLgel, which is produced in a series of individual pore sizes, formed the basis for the original product line of SEC columns. Developments in the refinement of particle sizing introduced the benefits of smaller particle size and more efficient columns, which significantly reduced SEC analysis time through a reduction in the number of columns required for... 

The field of aqueous SEC is of growing interest and also represents an area of active development by several companies, with Polymer Laboratories included. In this area, contrary to the organic SEC scenario, a variety of polymer chemistries are employed in the preparation of the column packing materials. This fact alone makes the practice of aqueous SEC more difficult than its organic counterpart and requires the suppliers of such columns to offer a good level of technical support to the column user. This chapter outlines the characteristics and applications of PL aquagel-OH aqueous SEC columns. 

Polymer Laboratories employs their own individual design of column hardware, which was developed to give low dispersion, high-performance SEC columns. The components used in the design are specified to very low tolerances dimen-... 

Commercial grades of PVP, K-15, K-30, K-90, and K-120 and the quaternized copolymer of vinylpyrrolidone and dimthylaminoethylmethacrylate (poly-VP/ DMAEMA) made by International Specialty Products (ISP) were used in this study. PEO standard calibration kits were purchased from Polymer Laboratories Ltd. (PL), American Polymer Standards Corporation (APSC), Polymer Standards Service (PSS), and Tosoh Corporation (TSK). In addition, two narrow NIST standards, 1923 and 1924, were used to evaluate commercial PEO standards. Deionized, filtered water, and high-performance liquid chromatography grade methanol purchased from Aldrich or Fischer Scientific were used in this study. Lithium nitrate (LiN03) from Aldrich was the salt added to the mobile phases to control for polyelectrolyte effects. 

SEC measurements were made using a Waters Alliance 2690 separation module with a 410 differential refractometer. Typical chromatographic conditions were 30°C, a 0.5-ml/min flow rate, and a detector sensitivity at 4 with a sample injection volume of 80 fil, respectively, for a sample concentration of 0.075%. All or a combination of PEO standards at 0.05% concentration each were used to generate a linear first-order polynomial fit for each run throughout this work. Polymer Laboratories Caliber GPC/SEC software version 6.0 was used for all SEC collection, analysis, and molecular weight distribution overlays. 

TosoHaas columns are styrene cross-linked with divinylbenzene (DVB). Columns of similar composition are available from Polymer Laboratories (PL Gel), Waters (Ultrastyragel), Shodex, Jordi (JordiGel), and many others. Columns based on derivatized silica are also available, but are less widely used. 

SW series and Alltech Macrosphere series), hydroxylated methacrylate (e.g., TosoHaas TSK PW series. Waters Ultrahydrostyragel, Shodex OHPak), functionalized styrene/DVB (Polymer Laboratories PL aquagel-OH), poly(vinyl alcohol) (Shodex OHPak), and others. 

Commercial narrow standards [such as poly(ethylene glycol) (pEG), polystyrene sulfonate, pAA, poly w-vinyl pyrrolidinone, dextrans] are available from American Polymer Standards Corporation, Polymer Laboratories, Polymer Standards Service USA, Toyo Soda, and others. While these standards are often not as narrow as pSty or pMMA that has been anionically polymerized, they are acceptable for narrow standard calibrations. 

FIGURE 19.3 Comparison of pSty standards on Polymer Laboratories PLgel mixed A 20-/Ltm and Waters HT IO- Am columns. 

The elution of such gels is an example not of size exclusion but rather of hydrodynamic fractionation (HDF). However, it must be remembered that merely being able to physically fit an insoluble material through the column interstices is not the only criterion for whether the GPC/HDF analysis of an insoluble material will be successful. A well-designed HDF packing and eluant combination will often elute up to the estimated radius in Eq. (5), but adsorption can drastically limit this upper analysis radius. For example, work in our laboratory using an 8-mm-bead-diameter Polymer Laboratories aqueous GPC column for HDF found that that column could not elute 204 nM pSty particles, even though Eq. (5) estimates a critical radius of —1.5 jam. 

Standards PEG and PEO (American Polymer Standards Corporation) PSC (Polymer Laboratories)... 

Polymer Laboratories was able to guarantee column supply by making up the gel in large batches and keeping packed columns in stock. This simple procedure has resulted in our never being without columns over the 10 years that they have been our supplier. 

The final step in the process of standardizing our columns was to try and maintain the high quality of columns from batch to batch of gel from the manufacturer. This was done by following the basic procedures outlined earlier for the initial column evaluation with two exceptions. First, we did not continue to use the valley-to-peak ratios or the peak separation parameters. We decided that the D20 values told us enough information. The second modification that we made was to address the issue of discontinuities in the gel pore sizes (18,19). To do this, we selected six different polyethylenes made via five different production processes. These samples are run every time we do an evaluation to look for breaks or discontinuities that might indicate the presence of a gel mismatch. Because the resins were made by several different processes, the presence of a discontinuity in several of these samples would be a strong indication of a problem. Table 21.5 shows the results for several column evaluations that have been performed on different batches of gel over a 10-year period. Table 21.5 shows how the columns made by Polymer Laboratories have improved continuously over this time period. Figure 21.2 shows an example of a discontinuity that was identified in one particular evaluation. These were not accepted and the manufacturer quickly fixed the problem. 

Polymer Laboratory, Department of Materials Science, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland... 

Polymers, S.R. Holding and E. Meehan, Rapra Technology Ltd. and Polymer Laboratories Ltd. Report 109 Rubber Injection Moulding - A Practical Guide, J.A. Lindsay. 

The concept of task automation for the R D worker, discussed in Chapter 1 of Computer Applications in the Polymer Laboratory, ACS Symposium Series No. 313, is well on the way to being realized through the proliferation of powerful, low-cost universal work stations coupled to... 

Mark. E. Koehler, Computer Applications in the Polymer Laboratory. ACS Symposium Series 313, 1986. 

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