MWCNT-polymer nanocomposites

The results on MWCNT-polymer nanocomposites reported in this chapter demonstrate the versatility of the latex concept to prepare nanocomposites with a broad range of "home-made" or industrially manufactured polymers, namely, amorphous, semi-crystalline, and blended polymer matrixes. Note that blending can further be done in very different fashions, i.e., in situ, while the emulsion polymerization proceeds, by mixing of two different polymer latexes synthesized independently from each other, or by a "masterbatch approach." This study confirms that the CNT-polymer interactions are of major importance to influence the percolation behavior of the nanocomposites, as well as the viscosity, morphology, and the intrinsic conductivity of the polymer matrix. 

Figure 9.3. SEM images of MWCNT-g-PLLA (3000)/PLLA nanocomposite at (a) lower and (b) higher magnifications (c) MWCNT-g-PLLA (15000)/PLLA nanocomposite and (d) PLLA-MWCNT-COOH nanocomposite. Reprinted with permission from G. Chen et al., Journal of Polymer Chemistry, Vol. 109, p. 22237, 2005, 2005, Elsevier Science Ltd.

Alternatively, hydrophilic multi-hydroxyl poly(GMA-OH)-grafted MWCNTs could be converted into multicarboxyl polymer-functionalized CNTs by reaction with succinic anhydride and then used as templates to efficiently sequestrate metal ions such as Ag", Co ", Ni , Au , La and (Scheme 5.3), generating MWCNT-polymer/metal hybrid nanocomposites, nanowires or necklace-like nanostructures, depending on the grafted polymer content and the nature of the captured metals. The combination of SEM, TEM and energy dispersive spectroscopy (EDS) characterizations demonstrated the structure and elements of the hybrid nano-objects. 

Koo, J. (2006) Polymer Nanocomposites Processing, Characterization, and Applications. McGraw-Hill, ISBN 0071458212,9780071458214, New York Koval chuk, A. Shevchenko, V. Shchegolikhin, A. Nedorezoca, P. Klyamkina, A. Aladyshev, A. (2008) Effect of carbon nanotube functionalization on the structural and mechanical properties of polypropylene/MWCNT composites. Macromol. Vol.41, No.20, pp.7536-7542... 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

Among the many potential applications of carbon nanotubes (CNTs), their use as reinforcing fillers for fhe fabrication of polymer nanocomposites has received considerable attention [1-4]. Both single-walled and multiwalled carbon nanotubes (SWCNTs and MWCNTs, respectively) are noted for their outstanding thermal, electrical, and mechanical properties. Polypropylene (PP) is a widely used thermoplastic because of its low cost, good processability, and well-balanced physical and mechanical properties. Products of PP take the forms of fibers, films, and molded articles. This chapter highlights the microstructure and properties of PP/CNT nanocomposites. Since most studies dealt with isotactic polypropylene, the term TP" in this chapter refers to isotactic polypropylene unless otherwise stated. 

Han Z, Fina A (2011) Thermal conductivity of carbon nanotubes and their polymer nanocomposites a review. Prog Polym Sci 36 914-944 Her SC, Lai CY (2013) Dynamic behavior of nanocomposites reinforced with multi-walled carbon nanotubes (MWCNTs). Materials 6 2274—2284... 

In recent decades, there have been many attempts to fabricate CNT/PANI composites [329-337]. The incorporation of nanotubes into PANI can result in novel composite materials with enhanced electrical, electrochemical, and mechanical properties. Eor example, Yu et al. prepared MWCNT/PANI nanocomposites through in situ inverse microemulsion synthesis [334]. Such nanocomposites are characterized by very strong interaction between MWCNTs and conducting polymers. Moreover, MWCNT/PANI core-shell nanowires exhibited better thermal stability and electrical conductivity than the pure PANI. The electrical conductivity of MWCNT/PANI composite containing 1 wt% of MWCNTs increased by one order of magnitude (pure PANI 0.02Scm MWCNT/PANI composite 0.20Scm-i) [334]. 

Dynamic frequency tests are used to explore the microstructure and network formation of the nanocomposites in presence of multiple fillers and their chemical modifications. The storage modulus (G ) of neat PU, PU/MWCNT, PU/functionalized MWCNT/CB nanocomposites measured at 150 °C is logarithmically plotted as a function of angular frequency (m) in Fig. 13 [ 117]. Incorporation of unmodified MWCNT causes dramatic changes in viscoelasticity of polymer... 

Fig. 22 Effect of the silica/ MWCNT hybrid loading ratio on the tensile strength of the NR/silica/MWCNT hybrid nanocomposites (reproduced with permission of John Wiley Sons, Inc., H. Ismail et al.. Journal of Applied Polymer Science [46])...

Even if conductivity results of CNT/polymer nanocomposites are commonly reported in terms of wt%, mainly because of lack of precise CNT density values, percolation is considered to be a volumetric phenomenon. In an attempt to fairly compare conductivity results obtained for systems containing either SWCNTs or MWCNTs dispersed in a given polymer matrix, the percolation threshold values of the various nanocomposites series were calculated in terms of vol% CNT. See ref. [28] for the details of the calculation. 

Conductivity mechanism in CNT/polymer nanocomposites SWCNTs vs. MWCNTs... 

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