Polymer Nanocomposite Analysis

After the nanocomposite is prepared, it must be analyzed to confirm nanocomposite structure and dispersion. Polymer-clay nanocomposites have been described using the terms exfoliated, mixed intercalated-exfoliated, intercalated, and immiscible (or microcomposite) in aU of these categories there are both ordered and disordered versions. 

For other nanoparticles, such as nanotubes, nanofibers, and colloidal (spherical particles), terms for the degree of nanoparticle dispersion have not been clearly defined. The term exfoliated has been used for nanotubes aud nanofibers to describe unbundling of the primary nanofiber aggregates as well as breakup of colloidal nanoparticle primary aggregates. Since there is no layered structure in nanotubes, fibers, or colloidal particles, the intercalated description cannot be used for these systems. Immiscible and microcomposite descriptions are still apphcable to these types of nanoparticles, and are used to describe examples where the nanoparticles never disperse from their primary particles into the polymer matrix. 

These descriptive terms are used to classify the degree of nauoscale dispersion as well as global micro- and macroscale dispersion of the nanoparticles in the polymer matrix. Since no numerical standards exist for rating the degree of nanoparticle dispersion in the polymer matrix, use of these terms is strictly qualitative and continues to be area of some controversy, as the classification of dispersion is mostly the opinion of the user. Unfortunately, not all researchers in the nanocomposite area use these terms in the same ways. The definition of intercalated comes from an 

XRD measurement in which the clay layers are seen to be still in registry exfoliated is defined as the sitnation when this registry is lost. Some researchers use the term exfoliated simply to mean well dispersed at the nanometer level, either intercalated or exfoliated, others mean as stated above. Another problem is that some use the terms exfoliated and delaminated interchangeably where as others will argue that delamination is a better state of dispersion than exfoliation. It is unlikely that there is any near-term solution to this problem, so one must critically evaluate the type of system that is being described. 

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Vaia, R. A., Liu, W., and Koemer, H. Analysis of small-angle scattering of suspensions of organically modified montmorillonite Implications to phase behavior of polymer nanocomposites, J. Polym. Sci. B.Polym. Phys. (2003), 41, 3214-3236. 

D. Wang, K. Echols, and C.A. Wilkie, Cone calorimetric and thermogravimetric analysis evaluation of halogen-containing polymer nanocomposites, Fire Mater., 2005, 29 283-294. 

CNT nanocomposites morphological and structural analysis is often done by TEM but an extensive imaging is required then to ensure a representative view of the material. Moreover, carbon based fillers have very low TEM contrast when embedded in a polymer matrix. The application of microscopy techniques is very useful to control the status of CNTs at any time during the preparation process of CNT/polymer nanocomposites, and moreover, to gain insights on parameters important for a better understanding the performance of the final nanocomposite material based on CNTs. 

Analysis of diversity in response to polar and nonpolar vapors of all screened polymers was performed using PCA analysis followed by cluster analysis. The scores plots of the first three PCs (Fig. 5.12) illustrate the diversity of performance of all sensing polymers. The larger the distance between polymer data points, the larger the difference in the response pattern between the respective CdSe/polymer nanocomposites. To quantify this diversity, cluster analysis was further performed where the distances based on principal component scores were adjusted to unit variance.45 This distance measure, known as Mahalanobis distance, accounts for the different amount of variation in different directions. An example of such difference is shown in Fig. 5.12a, b, where the distance between polymer 4 and other polymers is much larger on the plot of PC 1 vs. PC 2 when compared with the plot of PC 2 vs. PC 3. 

The modem methods of experimental and theoretical analysis of polymer materials stmcture and properties allow not only to confirm earlier propounded hypotheses, but also to obtain principally new results. Let us consider some important problems of partictrlate-filled polymer nanocomposites, the solution of which allows to advance substantially in these materials properties understanding and prediction. 

Thus, the aforementioned used nanoscopic methodics allow estimating both interfacial layer and structural special features in polymer nanocomposites and its sizes and properties. For the first time it has been shown that two consecutive interfacial layers are formed in elastomeric particulate-filled nanocomposites, which are reinforcing elements for the indicated nanocomposites. The proposed theoretical methodics of interfacial layer thickness estimation, elaborated within the fiamewoiks of finctal analysis, give well enough correspondence to the experiment. 

The discrepancy indicated requires the application of principally differing approaches to the polymer nanocomposites melt viscosity description. Such an approach can be fractal analysis, within the ffamewoik of which, the authors used the following relationship for fractal liquid viscosity (h) estimation ... 

Polymer nanocomposite materials as a new insulation material also have been given attention because the properties of the original material can be drastically improved by adding a few percent of nano-sized filler. Polymer nanocomposites for HV insulation have been extensively being studied in recent years because of their unique properties and ability to enhance electrical performance. The analysis result showed that DC conductivity exhibits... 

Ma, J. Qi, Z. Hu, Y. (2001) Synthesis and characterization of polypropylene/day nanocomposites. J. Appl. Polym. Sci. Vol.82, No.l4, pp.3611-3617 Moniruzzaman, M. Winey, K. (2006) Polymer Nanocomposites Containing Carbon Nanotubes. Macromol. Vol.39, No.l6, pp. 5194-5205 Moore, D. Reynolds, R. (1997) X-Ray Diffraction and the Identification and Analysis of Clay Minerals (2nd edition). University Press, ISBN 0195087135, New York Ogata, N. Kaawakage, S. Ogihara, T. (1997) Poly(vinyl alcohol)-Clay and Poly(ethylene oxide)-Qay Blends Prepared Using Water as Solvent. /. Appl. Polym. Sci. Vol.66, No.3, pp.573-581... 

The modem methods of experimental and theoretical analysis of polymer materials structure and properties allow not only to confirm earlier propounded hypotheses, but to obtain principally new results. Let us consider some important problems of particulate-filled polymer nanocomposites, the solution of which allows to advance substantially in these materials properties understanding and prediction. Polymer nanocomposites multicomponentness (multiphaseness) requires their stmctural components quantitative characteristics determination. In this aspect interfacial regions play a particular role, since it has been shown earlier, that they are the same reinforcing element in elastomeric nanocomposites as nanofiller actually [1]. Therefore, the knowledge of interfacial layer dimensional characteristics is necessary for quantitative determination of one of the most important parameters of pol5mier composites in general their reinforcement degree [2, 3]. 

What information is obtained from the dynamic mechanical analysis of vegetable oil-based polymer nanocomposites ... 

Dynamic Mechanical Analysis of Clay-Polymer Nanocomposites... 

Dynamic mechanical analysis is done by researchers to analyze the viscoelastic properties of polymer nanocomposites [3,73,80]. Omrani et al. studied the influence of nano-alumina on the viscoelastic properties of epoxy in... 

Nanocrystalline silicon Polyethylene Polymer nanocomposites Spectroscopy UV-protective film X-ray diffraction analysis... 

The art of filler dispersion in polymer matrix is easily determined by X-ray analysis especially WAXS analysis. The intensity and position of X-ray diffraction peaks reveals the exact idea regarding the morphological structure of polymer nanocomposites. Figure 22.11 compares reduced graphite oxide dispersions in NR matrix by different processes such as milling and solution casting methods. 

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