Industrial polymers, analysis

It is of course of interest to determine which of the methods of quantitation provides the most accurate and precise quantitative data. It is equally important to consider the constant trade-off for precision and sensitivity. At very low concentrations, precision often becomes limited by extraneous factors, such as wall effects. In such cases, high-precision measurements are becoming virtually unobtainable. In analogy to the Quantitative Ingredient Declarations (QUID) in food analysis, which require statements as to the uncertainty of the measurement and the variability of the results (sampling ), also for industrial polymer analysis intra- and interlaboratory variation and the meaning of average analytical results needs to be established. It is the responsibility of the analyst to adequately describe the instrumentation and performance to duplicate the repeatability and accuracy of the developed method. 

The utilization of commercially available finite element packages in the simulation of routine operations in industrial polymer processing is well established. However, these packages cannot be usually used as general research tools. Thus flexible in-house -created programs are needed to carry out the analysis required in the investigation, design and development of novel equipment and operations. 

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 final chapter summarises the book with special emphasis on the future of polymer/additive analysis. The methods, results and their evaluation presented in this chapter encompass all material developed in the book s previous chapters. Three appendices contain lists of symbols, describe the functionality of common additives (as a reminder) and show an excerpt of an industrial polymer additive database. 

A real breakthrough of analytical SFE for in-polymer analysis is still uncertain. The expectations and needs of industrial researchers and routine laboratories have not been fulfilled. SFE presents some severe drawbacks (optimisation, quantification, coupling, and constraints as to polarity of the extractable analytes), which cannot easily be overcome by instrumental breakthroughs but... 

Gas chromatography is widely applied in the paint and varnish industry for analysis of solvents, oils, resins, plasticisers and polymers (by pyrolysis techniques). GC-TCD and GC-FTD on capillary and packed columns are used for direct determination of solvents in paints [143,144], DIN ISO 11890-2 describes an officially approved GC test procedure for solvents in paints and varnishes (VOCs 0.1-15%). 

The best method or the most suitable combination of methods can be discussed only in regard to the actual analytical problem. The ideal method for polymer analysis in an industrial environment is often essentially that practical one which identifies and quantitates the desired components at the lowest acceptable total cost for the customer, compatible with the desired accuracy and time constraints. Three examples may illustrate the necessary pragmatic trade-off. Despite being old methods, classical polymer/additive analysis techniques, based on initial additive separation from the polymer matrix through solvent extraction methods followed by preconcentration, still enjoy great popularity. This... 

The purpose of this monograph, the first to be dedicated exclusively to the analytics of additives in polymers, is to evaluate critically the extensive problemsolving experience in the polymer industry. Although this book is not intended to be a treatise on modem analytical tools in general or on polymer analysis en large, an outline of the principles and characteristics of relevant instrumental techniques (without hands-on details) was deemed necessary to clarify the current state-of-the-art of the analysis of additives in polymers and to accustom the reader to the unavoidable professional nomenclature. The book, which provides an in-depth overview of additive analysis by focusing on a wide array of applications in R D, production, quality control and technical service, reflects the recent explosive development of the field. Rather than being a compendium, cookery book or laboratory manual for qualitative and/or quantitative analysis of specific additives in a variety of commercial polymers, with no limits to impractical academic exoticism (analysis for its own sake), the book focuses on the fundamental characteristics of the arsenal of techniques utilised industrially in direct relation... 

This volume on "Molecular Characterization and Analysis of Polymers" has been edited by John M. Chalmers and Robert J. Meier, both of whom have considerable experience in the industrial sector. They have compiled a broad compilation of chapters on the various aspects of polymer analysis and placed a clear and useful emphasis on problem solving, rather than on the techniques used. 

The specific constraints and requirements of continuous-flow NMR will be explained in the first chapter, whereas specific applications, such as biomedical and natural product analysis, LC-NMR-MS and LC-NMR in an industrial environment, together with polymer analysis, will be discussed separately. Thus, the reader will obtain a broad overview of the application power of LC-NMR and the benefits of its use. He/She will also be introduced to the pitfalls of this technique. Special attention will be given to the exciting newer coupled techniques such as SFC-NMR and capillary HPLC-NMR. However, new emerging future developments will also be discussed thoroughly. 

This chapter examines two industrial polymer processes. Thermodynamic analysis is used as a tool to locate, in a matter-of-fact fashion, process inefficiencies. Some sample process improvement options are discussed. 

Reversed-phase chromatography is the most popular mode for the separation of low molecular weight (<3000), neutral species that are soluble in water or other polar solvents. It is widely used in the pharmaceutical industry for separation of species such as steroids, vitamins, and /3-blockers. It is also used in other areas for example, in clinical laboratories for analysis of catecholamines, in the chemical industry for analysis of polymer additives, in the environmental arena for analysis of pesticides and herbicides, and in the food and beverage industry for analysis of carbohydrates, sweeteners, and food additives. 

In size-exclusion chromatography, the separation is based on the partial exclusion of analytes from the pores of the packing, due to the size of the analyte. It is used largely for the analysis or characterization of industrial polymers and biopolymers, but its separation range extends all the way down to oligomers. Known also as gel-permeation chromatography, it is one of the parent techniques of today s instrumental HPLC. 

NIR is increasingly used in process and environmental analysis, the food industry, agriculture, the pharmaceutical industry and polymer analysis. In-line measurement with fiber optics and rapid multi-component quantification are the most important advantages of NIR spectroscopy. In comparison to mid-infrared, NIR analysis is much faster and more versatile. Most samples are analysed in one minute or less. Often chemometric methods must be applied to determine the parameter of interest... 

These two characteristics are not always encountered, especially in the cases of addition polymerization of monomers with double bonds. Isomerization of the monomers may occur, or false bonding of monomeric units into the chain may take place during the actual step of adding monomer onto the polymer chain. Consequently the assumed chemical structure of the polymer must always be carefully verified by analytical methods. Analysis is especially important with industrial polymer production, since the preparation history is not often known exactly. The chemical names of industrial or commercial polymers are often nothing more than a kind of generic name. Commercial poly(ethylenes), for example, despite the ascribed name, are often not homopolymers, but copolymers of ethylene and propylene. As well as that, commercial polymers practically always contain additives such as antioxidants, uv absorbers, fillers, etc. In the addition polymerization of monomers with multiple bonds, head-to-head and tail-to-tail structures are always to be expected together with the normal head-to-tail bonding, as can be seen, for example, with vinyl compounds such as CH2=CHR ... 

The analysis of polydisperse polymers by MS methods poses some problems that have been only recently solved. Polydisperse polymers (including many industrial polymers) are made of a mixture of macromolecular chains that have quite different sizes, ranging from dimers and trimers, up to chains with thousands of units. Using MS methods, all the oligomer chains can be ionized, but the ratio between the number of ions of a given size and the number of molecules of that size (i.e., the ion yield as a function of chain size) is not constant. Actually, the ion yield decreases with chain Imgth, implying that Eqs. (2.1) and (2.2) cannot be reliably used to compute Mn and Mw. 

Raman spectrometry This is one of the nondestructive methods of polymer analysis polymer samples can be measured directly, without any pretreatment. While Raman spectra primarily reveal the vibrations of the molecular skeleton (e.g., carbon atom chains), IR spectra are better suited for observing the vibrations of polar groups. An advantage of Raman spectrometry is the possibility of measurement over the whole wavelength range, from 5 to 4000cmRaman spectra provide information and limits of detection similar to those of IR spectra, but IR spectra are easier to obtain and cheaper. Therefore, Raman spectrometry is less common in industrial analyses of plastics. 

It is interesting to note that the development of TREF as a routine polymer analysis tool has until recently taken place almost exclusively within industrial research laboratories. Further, the more sophisticated versions of the TREF have emerged from laboratories associated with companies engaged in the production of linear low density polyethylenes (LLDPE). Clearly this has been driven by the need to understand the nature of LLDPE which exhibits behavior indicative of considerable structural heterogeneity. This is in spite of the fact that, compared to conventional low density polyethylene (LDPE), it is narrow in MWD and contains little or no long-chain branching. 

R159 S. D. Hanton and K. G. Owens, MALDI MS Applications for Industrial Polymers , in Chemical Analysis (Hoboken, NJ, United States), ed. L. Li, John Wiley Sons, Inc., 2011, Vol. 175, MALDI Mass Spectrometry for Synthetic Polymer Analysis, p. 267. 

The rest of the potential advantages included in the list above have been hardly ever applied to the field of polymer analysis so far. In fact, coupling of the ETV to an instrument equipped with a dynamic reaction cell has been reported only once, with the purpose of further removal of matrix-related interferences, allowing the use of isotope dilution for calibration [33]. Likewise, isotope ratio determination has been only reported for the direct analysis of particulate uranium from the nuclear industry embedded in polycarbonate films [35], while no references can be found for speciation analysis in polymers. This circumstance is probably due to the fact that there has not been a real need for this analytical information to be obtained, although there is no... 

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