Matrix polymer analysis

Although PFE lacks a proven total concept for in-polymer analysis, as in the case of closed-vessel MAE (though limited to polyolefins), a framework for method development and optimisation is now available which is expected to be an excellent guide for a wide variety of applications, including non-polyolefinic matrices. Already, reported results refer to HDPE, LDPE, LLDPE, PP, PA6, PA6.6, PET, PBT, PMMA, PS, PVC, ABS, styrene-butadiene rubbers, while others may be added, such as the determination of oil in EPDM, the quantification of the water-insoluble fraction in nylon, as well as the determination of the isotacticity of polypropylene and of heptane insolubles. Thus PFE seems to cover a much broader polymer matrix range than MAE and appears to be quite suitable for R D samples. 

For the analysis of nonvolatile compounds, on-line coupled microcolumn SEC-PyGC has been described [979]. Alternatively, on-line p,SEC coupled to a conventional-size LC system can be used for separation and quantitative determination of compounds, in which volatility may not allow analysis via capillary GC [976]. An automated SEC-gradient HPLC flow system for polymer analysis has been developed [980]. The high sample loading capacity available in SEC makes it an attractive technique for intermediate sample cleanup [981] prior to a more sensitive RPLC technique. Hence, this intermediate step is especially interesting for experimental purposes whenever polymer matrix interference cannot be separated from the peak of interest. Coupling of SEC to RPLC is expected to benefit from the miniaturised approach in the first dimension (no broadening). Development of the first separation step in SEC-HPLC is usually quite short, unless problems are encountered with sample/column compatibility. 

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... 

Insulating interlayers separates the inclusions from each other and from the matrix polymer in such system degradation catalyzed by nanoparticles starts within the interlayer. This layer should provide less combustible degradation products. A new method for the formation of PEP resin has been proposed recently [21]. A detailed analysis of PEP revealed the combined (gas and solid phase) mechanism of FR action in this material [41], This polymer was selected for forming an interlayer around clay nanoparticles. The monomer components were introduced during the compounding process and the interlayer was formed by in situ curing. 

The changes in polymer appearance after exposure to aqueous media were evaluated using light and SEM microscopy. Before exposure to buffer, the polymer is transparent. After exposure to buffer the polymer became opaque, and when it was cut, two different regions were found the outer region which is gel and the core, which appears as a soft solid matrix. SEM analysis of the interface of the polymer exposed to buffer showed that a kind of a rigid network was formed across the polymer sample. This network causes the polymer drop to keep its shape in water. 

HS-SPME is a very useful tool in polymer analysis and can be applied for absolute and semi-quantitative determination of the volatile content in polymers, for degradation studies, in the assessment of polymer durabihty, for screening tests and for quality control of recycled materials. For quantitative determination of volatiles in polymers, SPME can be combined with multiple headspace extraction to remove the matrix effects. If the hnearity of the MHS-SPME plot has been verified, the number of extractions can be reduced to two, which considerably reduces the total analysis time. Advantages of MHS-SPME compared to MAE are its higher sensitivity, the small sample amount required, solvent free nature and if an autosampler is used a low demand of labor time. In addition, if the matrix effects are absent, the recovery will always be 100%. This is valuable compared to other techniques for extracting volatiles in polymers in which the recovery should be calculated from the extraction of spiked samples, which are very difficult to produce in the case of polymeric materials. 

Matrix-Assisted Laser Desorption/Ionization (MALDl) This topic has received much attention since several years ago, especially with regard to its application to polymer analysis. 

XRD is a rather simple and widely used technique for the characterization of a layered-clay dispersion in a polymer matrix. WAXS analysis was used to quantify the height between adjacent silicate platelets, and subsequently to prove the widening of this distance as the matrix polymer intercalates between the galleries. Changes in the value of 20 reflect changes in the... 

For S5mthetic polymers, the most popular desorption/ionization method has been matrix-assisted laser desorption/ionization (MALDI-MS, Chapter 10). Several other techniques have important applications in polymer analysis. The more widely used methods are covered in this book electrospray (Chapter 4), field ionization/desorption (Chapter 6), fast atom bombardment (Chapter 7), secondary ion mass spectrometry (Chapter 8), and laser desorption (Chapters 9 and 11). 

Lasers have provided a convenient means to create gas phase ions from nonvolatile subsfances. In fhis chapter, application of lasers to FTMS for polymer analysis will be considered. The earliest combination of direct laser desorption and laser ablation techniques with FTMS will be discussed first. Moving on from that topic, the impact of matrix-assisted laser desorption/ ionization (MALDI) on FTMS will be addressed, with particular emphasis... 

Yalcin, T., Dai, Y, and Li, L., Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry for Polymer Analysis Solvent Effect in Sample Preparation, /. Am. Soc. Mass Specirom., 9, 1303,1998. 

ATR-FTIR spectroscopy was used to monitor the uptake of urea into a silicone polymer. Analysis of the time-dependent changes in the IR absorbances of urea and silicone leads to an estimate of the diffusion coefficient for urea that is in close agreement with a value obtained using a bulk transport method (involving radiolabelled permeant). The silicone polymer was medical grade silicone pressure-sensitive adhesive (X7 201). ATR-FTIR is proposed as a rapid and accurate method of rapidly and accurately determining solute diffusion within a polymer matrix. 12 refs. 

If Dp depends significantly on Cp, extrapolation to Cp 0 must be performed. The initial slope of the dependence of Dp on probe concentration, and the slope s dependence on matrix concentration, have been measured in some systems and should be accessible to theoretical analysis. In this review If the probe and matrix polymers differ appreciably in molecular weight or chemical nature, the phrase probe diffusion coefficient is applied. If the probe and matrix polymers differ primarily in that the probes are labelled, the phrase self diffusion coefficient is applied. The tracer diffusion coefficient is a single-particle diffusion coefficient, including both the self cind probe diffusion coefficients as special cases. The interdiffusion and cooperative diffusion coefficients characterize the relaxation times in a ternary system in which neither m lcrocomponent is dilute. 

The example shown in Figure 8.2 illustrates that the selection of a proper matrix is important to generate a MALDI spectrum reflective of the polymer sample composihon. In this case, if only DHB were used, the MALDI spectrum produced would not reveal the low mass oligomers (m/z<10000) actually present in this sample. As only a handful of matrices are found to be practically useful for polymer analysis, it is often worthy spending the time to test these matrices on a given sample to identify the best matrix that provides good sensitivity, mass resolution, and reproducibiUty over a broad mass range. 

GO Yalcin, T., Dai, Y., and U, L (1998) Matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry for polymer analysis solvent effect in sample preparation. J. Am. Soc. Mass Spectrom., 9,1303-1310. 

Fig. 1 Illustration of flexible polymers in dilute solution ic < c ), entanglement threshold (c = c ), and semidilute solution (c > c ) regimes, as well as cross-linked chain. One chain is drawn as a thick line for easier visualization. The small circle in the semidilute solution regime represents the blobs of size 4-Source From The separation matrix, in Analysis of Nucleic Acids by Capillary Electrophoresis ...

Basile, F. Kassalainen, G.E. Williams, S.K.R. Interface for direct and continuous sample-matrix deposition onto a MALDI probe for polymer analysis by thermal field flow fractionation and off-line MALDI-MS. Anal. Chem. 2005, 77, 3008-3012. 

Jr., and Jana, S.C. (2010) Analysis of noninteractions between the nanoparticulate fillers and the matrix polymer as applied to shape memory performance. J. Mater. 

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