Plastics analysis instrumentation

Torsional Braid Analyzer (TBA) B 10-1 -1 Plastics Analysis Instruments, Princeton, N.J. 

The TBA/TP instrumental system is available from Plastics Analysis Instruments, Inc., Princeton, New Jersey, USA. 

Torsional braid analysis TBA (Plastics Analysis Instruments)... 

In torsional braid analysis (TBA) the sample is impregnated into a multistranded glass braid which acts as support. The method allows analysis of mechanically weak materials, and also materials which are available in very small amounts. Since the specimen is a composite the properties determined are only relative. The main use of TBA is in locating the temperatures of transitions and relaxations. The temperature range available is similar to that given above for conventional torsion pendulums. Manufacturers include Plastics Analysis Instruments Inc., Princeton, NJ, USA. 

A. Krause, A. Lange and M. Ezrin, Plastics Analysis Guide - Chemical and Instrumental Methods, Hanser Verlag, Munich (1983). 

Krause, A., Lange A., and Ezrin, M., Plastics Analysis Guide—Chemical and Instrumental Methods, translated by K. Ruby, Hanser Publishers, Munich (1979)... 

An instrument for the measurement of the intensity of emitted, reflected, or transmitted light. For the measurement of luminous intensity, a visual receptor element (the eye), may be used in the measuring device or a physical receptor element may be used which can be related to the calculated response of a standard observer. Harris DC (2002) Quantitative chemical analysis. W. H. Freeman Co., New York. Krause A, Lange A, Ezrin M (1988) Plastics analysis guide chemical and instrumental methods. Oxford University Press, UK. 

Kokhanovsky AA (2004) Light scattering media optics. Springer-Verlag, New York Krause A, Lange A, Ezrin M (1988) Plastics analysis guide chemical and instrumental methods. Oxford University Press, UK... 

The GC instrument is a rather simple, yet very powerful. It is one of the most common analytical tools used in plastics analysis. When used properly, it can provide both qualitative (identification) and quantitative (amount) information about the individual components in sample mixtures. For a mixture to be suitable for gas chromatographic analysis it should be relatively volatile at temperatures below 350°C (450°C for high-temperature GC). In other words, the components of interest must become a gaseous form by rapid heating without any degradation or destruction of their chemical structure. This does not mean that other components are not amenable to GC analysis. In theory, most components can be analyzed by GC if a proper sample pretreatment or proper sample introduction technique is used (e.g., pyrolysis GC, sample derivatization) [1-5]. 

This book deals almost exclusively with studying polymers, by far the widest application of thermal analysis. In this area, TA is used not only for measuring the actual physical properties of materials but also for clarifying their thermal and mechanical histories, for characterizing and designing processes used in their manufacture, and for estimating their lifetimes in various environments. For these reasons, thermal analysis instruments are routinely used in laboratories of the plastics industry and other industries where polymers and plastics are being manufactured or developed. Thus, thermal analysis is one of the most important research and quality control methods in the development and manufacture of polymeric materials as well as in industries that incorporate these materials into their products. 

In this chapter we have provided a guide to approaching a very complicated analytical problem. The analysis methods were chosen for their simplicity. In some cases a choice of methods is available plasticizers can be analyzed by extraction or by thermal analysis. Modem paired instruments, such as GC-MS and TGA-IR, provide very powerful techniques for separation and identification. Much more detail is available in the references listed in the bibliography. Atlas of Polymer and Plastics Analysis is a comprehensive source, particularly for IR analysis. 

Grieve, M.C., and Kearns, J.A. (1976). Preparing samples for the recording of infrared spectra from synthetic fibers. J. Forensic Sci., 21, 307-314. Krause, A., Lange, A., Ezrin, M. (1983). Plastic Analysis Guide Chemical and Instrumental Methods, Hanser Publishers, NY. 

NMR is a powerful tool for the determination of polymer sfructure. It is at its most sensitive when used on analytes in solution. Table 1 gives examples of solvents used for NMR. Amorphous plastics, such as polystyrene can be dissolved in deuterated chloroform, whereas for the less soluble semi-crystalline plastics (e.g., PET) solvents such as trichloroacetic acid have to be used. Of the conventional insttuments, both proton and carbon 13 instruments have been used in plastics analysis. Combinations of two solvents can be used to achieve a good degree of solubility and elevated temperatures (e.g., 70 °C) are also common. The proton NMR solvents can be used for carbon 13 experiments, but the reverse is rarely the case. 

The advent of bench top LC-MS instruments has enabled the analysis of stabilisers such as the organo-tin type to be re-examined and laboratories such as the Analysis Division at Rapra Technology Limited are investigating the capability of this technique in this area. This could be another area of plastics analysis where LC-MS replaces the more traditional techniques. 

Figure 12.6 illustrates the outline of such an analysis. An automatic pipette extracts a preset volume of the liquid sample (or solution) from a cup presented to it on a turntable. The measured sample is mixed with the reagents in the appropriate proportions, and propelled through the instrument by the peristaltic proportioning pump. This pump operates by means of moving bars, attached to a chain drive, which sequentially compress the plastic sample and reagent tubes to drive the liquids forward through the instrument. The incorporation of a succession of air bubbles at... 

Over 30 commercial formulations have been surveyed in depth. Compressive strength measurements permit the exclusion of materials obviously prone to fail under pressure. FTIR (MX-1, Nicolet Instrument Corp.) analysis has identified formulations with volatile diluents capable of chemically modifying the composite membrane. Through the use of FTIR it was possible with an otherwise successful formulation to identify the presence of butyl glycidyl ether (BGE) as a diluent. Subsequently experimentation showed that vapor of BGE is capable of plasticizing porous polysulfone with a drop in both flux and rejection of the membrane. Collaboration with the supplier resulted in substitution of a nonvolatile glycidyl ether diluent to avoid the problem. 

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