Polymers characterisation methods

J. P. Ibar and co-workers, in Polymer Characterisation Physical Property, Spectroscopic, and Chromatographic Methods, American Chemical Society, Washington, D.C., 1990, p. 167. 

Table 4.45 shows the main features of SEC. This technique has become an indispensable tool for polymer characterisation. SEC has some advantages over other LC methods, such as the predictability of the end of a chromatographic run and of the retention times in a calibrated chromatographic system. SEC is an attractive technique for prefractionation or sample clean-up prior to a more sensitive RPLC technique. This intermediate step is especially interesting for experimental purposes whenever polymer matrix interference cannot be separated from the peak of interest [647]. Disadvantages are that the whole separation must be eluted within the... 

Stretching a polymer in two perpendicular directions, either successively or by blowing a bubble of molten material, leads to its biaxial orientation, which strongly improves mechanical properties in the stretching directions and/or gas permeability (e.g., biaxial orientation of polypropylene leads to BOPP (for biaxially oriented polypropylene) or biaxial orientation of poly(ethylene terephthalate) gives CC>2-impermeable bottles for carbonated beverages.) (Characterisation methods for determining molecular orientation are considered in Chapter 8.)... 

In random degradation molecular mass decreases early, while in chain degradation the molecular mass of the polymer remains almost constant. Characterisation methods for molecular mass are thus very sensitive methods to follow random degradation. In contrast, as monomer is produced in chain depolymerisation, weight loss measurement techniques are the best methods to follow this kind of degradation. (Chapters 10-12, in Section IV, of this book focus on the methods used in the molecular characterisation and analysis of polymer degradation and polymer degradation mechanisms.)... 

Another polymer symposia was organised by IUPAC in 1947 in Liege. At this conference, the discussion included synthesis and technology of polymers like polyethylene, nylon, polyester. New characterisation methods such as x-ray scattering, x-rays, electron microscope, osmometry, nmr, IR, Raman spectroscopy, etc. were now available for characterisation of polymers. These methods become essential because of increasing complexity of new polymers. 

A wide variety of characterisation methods is available for analysing polymer structure and properties [1-5]. Some of the most frequently-used are listed in Table 2.2, with examples of the information they provide, especially in respect to polymer degradation and ageing. 

Polymer Characterisation by Thermal Methods of Analysis, J. Chiu Ed., Marcel Dekker New York (1974). 

Baranowski, R. and Whitmore, M. D. (1995). Journal of Chemical Physics 103,2343. Beredijk, N. (1963). Monomolecular film studies of polymers. Newer Methods of Polymer Characterisation. B. Ke. New York, Wiley-Interscience. 

H.N. Cheng, in Modern Methods of Polymer Characterisation, eds. H.G. Barth and J.W. Mays, Wiley-Interscience, New York (1991). 

Throughout the book numerous references are made to the available range of general purpose NMR spectroscopy texts. The reader should turn to these for a full introduction to solution and solid-state techniques and their application to chemical science. Alternatively, texts are available which treat NMR as one of the range of spectroscopies of relevance to polymer characterisation. The reader will also be made aware of some excellent works on specific aspects of polymer NMR, including microstructural determination and high-resolution solid-state methods. In a number of cases these would form a... 

Abstract This chapter deals with a brief account of thermal degradation of polymer-based blends, composites and nanocomposites. Different synthesising, preparation and characterisation methods of thermal degradation of polymer-based blends, composites and nanocomposites are discussed. Finally the applications, new challenges and opportunities for these thermal degradation of polymer-based blends, composites and nanocomposites are discussed. 

This article will provide a general overview of the emulsion polymerisation process and explain how the resulting latexes are used in industrial applications. An introduction to the basic concepts of emulsion polymers will be given, followed by a description of the various production processes and characterisation methods. The classes of emulsion polymers will be surveyed, and the commercial technologies and potential future uses discussed. A number of comprehensive texts on emulsion polymers are available for more in-depth study (60, 89, 94,95, 364, a.l-a.ll). 

It is beyond the scope of this book to deal with polymer-analytic methods which are used for material identification and characterisation on a molecular level and for the investigation of changes in the polymer molecule and additive properties. An overview about the various methods should be mentioned, which contains further references (Braun 1999 Hoffmann et al. 1977). However, three methods will briefly be discussed here which frequently play a role in the analysis of HDPE materials visco-simetry, gel permeation chromatography (GC) and Fourier transformed infrared spectroscopy (FTIR). 

Several qualitative and quantitive techniques have been evolved to characterise blowing agents in polymers. These methods include EGA [28-30], differential thermal analysis (DTA) [31, 32] and TGA [31, 32]. The EGA technique limitations are well-described by Jaafer and Sims [28] where rate of gas evolved is dependent on type of additive and... 

Bassett DC, Olley RH, Vaughan AS (2003) Specimen preparation for TEM of polymers. In Pethrick RA, Viney C (eds) Techniques in polymer organisation and morphology characterisation. Experimental methods in polymer characterisation. Wiley, Chichester Bovey FA (2007) NMR of polymers. eMagRes. Wiley Online... 

Several different characterisation methods are used routinely. These will now be considered in the context of how they apply to polymer variables and end-use requirements. 

Each of these product types has characteristic behaviours which can be recognised in one or more of the rheological profiles obtained from advanced characterisation methods. These are usually the characteristics which make a polymer well (or badly) suited to the end-use requirements. 

Miller [332] has shown that NIR transflectance is useful for polymer characterisation of food packaging materials. The method was applied to PE film (before and after stretching and heat-sealing), ny-lon/EVOH/nylon coextruded sheets (before and after annealing) and PE/nylon laminate (before and after pasteurisation). 

It is the case to notice some differences between MALDI-MS and SEC for MW and MWD determinations. Essentially, amongst these two methods SEC is the more physical and MALDI the more chemical approach. At variance to MALDI, SEC fails in determining low-MWs (<20 kDa). MALDI-ToFMS yields distribution, as opposed to in SEC (interconversion is not always obvious as MALDI-MS easily misses out a high-MW fraction). Compared with other traditional MW characterisation methods, MALDI uses a minimum amount of solvent. Arguably the most appropriate application of LC-MALDI-MS in the field of synthetic polymers is for calibration of a SEC system, that is, to convert SEC retention times into MW data. MALDI-MS yields inaccurate results for samples with PD > 1.3 but when combined with SEC this limitation can be overcome cfr. Chp. 7.3.4.2 of ref. [13a]). Online and off-line coupling of MALDI-ToFMS with SEC allows reliable SEC characterisation of polymers with broad MWD, where suitable standards for SEC calibration are not available. Off-line SEC-MALDI-ToEMS is used for calibration fo SEC when the universal calibration is not applicable. On-line SEC-MALDI-ToEMS is difficult (timing problem). Direct (LCCC)-MALDI-ToFMS coupling has been used for characterisation of PPO and PEO [306]. 

A review on the most versatile methods for studying surface properties of solids is available [12]. Takeguchi etal. [13] have recently reviewed progress in surface microanalysis for various polymer additives, such as stabilisers, softeners, fillers, etc. More extensive information on surface characterisation methods of polymers can be found in various recent books [4,5,14-16]. For quantitative surface analysis of materials, cfr. Chp. 6 and refs. [17,18]. 

Principles and Characteristics Surface mass spectrometry techniques measure the masses of fragment ions which are ejected from the surface of a sample to identify the atoms and molecules present. The techniques are complementary to electron spectroscopy since they provide extra absolute and surface sensitivity and give very specific molecular information. On unknown samples it is common to use a combination of electron spectroscopy and mass spectrometry for surface characterisation. Methods used for surface mass spectrometry are SIMS, SNMS, LDMS, LMMS, LSIMS, GD-MS and LA-ICP-MS. Of these, SIMS is by far the most important for polymer analysis. 

An early compilation of established quantitative infrared polymer/additive methods was published [164] no update seems to be available. Various reviews on quantitative (surface) IR analysis have appeared [18,130,159,165,166,166a]. Several textbooks discuss basic considerations concerning quantitative analysis by vibrational spectroscopy [167-169]. Data processing techniques for quantitative analysis are covered by Koenig [170], in particular regarding theory and application of FTIR to the characterisation of polymers. Hummel [171] has also discussed quantitative IR spectroscopic analysis of additives. 

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