Polymers, analysis

Polymer additives Polymer alloys Polymer analysis... 

RECENT ADVANCES IN POLYMER ANALYSIS BY MODERN PYROLYSIS-GAS CHROMATOGRAPHY/MASS SPECTROMTERY (Py-GC/MS)... 

Applications of ISS to polymer analysis can provide some extremely useful and unique information that cannot be obtained by other means. This makes it extremely complementary to use ISS with other techniques, such as XPS and static SIMS. Some particularly important applications include the analysis of oxidation or degradation of polymers, adhesive failures, delaminations, silicone contamination, discolorations, and contamination by both organic or inorganic materials within the very outer layers of a sample. XPS and static SIMS are extremely comple-mentar when used in these studies, although these contaminants often are undetected by XPS and too complex because of interferences in SIMS. The concentration, and especially the thickness, of these thin surfiice layers has been found to have profound affects on adhesion. Besides problems in adhesion, ISS has proven very useful in studies related to printing operations, which are extremely sensitive to surface chemistry in the very outer layers. 

P. B. Harrington, K. J. Voorhees, T. E. Street, F. Radicati di Brozolo, and R. W. Odom. Anal Chem. 61, 715, 1989. Presents a discussion of LIMS polymer analysis and pattern recognition techniques. 

TSK-GEL PW and TSK-GEL PWxl columns are shown in Pig. 4.11. Although many methods for polymer analysis have been developed satisfactorily on TSK-GEL PW columns, higher resolution can often be achieved with a TSK-GEL PWxL column. The smaller particle sizes of the resins packed in TSK-GEL PWxL columns provide almost 2.5 times the resolution of their TSK-GEL PW counterparts. In addition, with shorter TSK-GEL PWxl columns, higher resolution separations are possible in less than half the time, as shown in Pig. 4.12. 

Anionic and neutral polymers are usually analyzed successfully on Syn-Chropak GPC columns because they have minimal interaction with the appropriate mobile-phase selection however, cationic polymers adsorb to these columns, often irreversibly. Mobile-phase selection for hydrophilic polymers is similar to that for proteins but the solubilities are of primary importance. Organic solvents can be added to the mobile phase to increase solubility. In polymer analysis, ionic strength and pH can change the shape of the solute from mostly linear to globular therefore, it is very important to use the same conditions during calibration and analysis of unknowns (8). Many mobile phases have been used, but 0.05-0.2 M sodium sulfate or sodium nitrate is common. 

Application to polymer analysis Combination of individual pore sizes (columns or gels) to cover required molecular weight range Molecular weight range covered by single pore size... 

Warner, F. P., Dryzek, Z., and Lloyd, L. L. (1986). New Criteria Influencing the Selection of High Performance GPC Columns for Polymer Analysis. Presented at Antec, Boston, MA. 

Although the OTHdC has several unique applications in polymer analysis, this technique has several limitations. First, it requires the instrumentation of capillary HPLC, especially the injector and detector, which is not as popular as packed column chromatography at this time. Second, as discussed previously, the separation range of a uniform capillary column is rather narrow. Third, it is difficult to couple capillary columns with different sizes together as SEC columns. 

Figure 1. Flow chart of the Polymer Analysis program. The program Is entered from a larger program, NMRl. A database must be chosen or created for the spectrum at hand and a statistical model chosen. Options In the main menu Include calculation of probabilities associated with the model, simulation of spectra, and modification of the peak table or database.

Figure 5. The C-15 (125.76 Hz) spectrum of approximately 20% w/v copolymer vinylidene chloride Isobutylene In CDCI at 24°C and a peak listing from the Polymer Analysis program.

Dr. Charles Dumoulln is acknowledged for writing the original version of the Polymer Analysis program. Annmarie Lareau made some revisions and documented the code. 

In particular, for copolymers this required an orthogonal coupling of one GPC to another to achieve the desired cro fractionation before application of dual detectors. This method is really a new polymer analysis member of a family of approaches developed in the literature which we are now terming "Orthogonal Chromatogr hy . It not only provides both a cro fractionation approach for copolymers and a new way of determining the GPC s "imperfect resolution" it also enables separation mechanisms previously reserved for the liquid chromatography of small molecules to be used for polymer analysis. 

Furthermore, in the more general case we are concerned with a variation of composition and sequence length distribution not only as a function of retention volume but within each chromatogram area segment (or "slice ) at each retention volume. A significant polydispcrsity of one of these properties within a chromatogram slice can easily invalidate the polymer analysis described above. 

Engelhardt, K and Groscke, O. Capillary Electrophoresis in Polymer Analysis. Vol 150, pp. 189-217. 

Kdhler, W and Schdfer, R, Polymer Analysis by Thermal-Diffusion Forced Rayleigh Scattering. Vol. 151, pp. 1-59. 

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