CNT-filled polymer blend

Similar results are also obtained from the CNT-filled polymer blends such as CNT-filled polyethylene terephthalate (PET)/polyvinylidene fluoride, PET/nylon 6,6, PET/polypropylene, and PET/high-density polyethylene blends. 

Table 12.3 The co value and the predicted CNT location for four CNT-filled polymer blends...

The electrical conductivities of injection-molded, CNT-filled polymer blends are summarized in Table 12.4. For comparison. Table 12.4 also includes the literature value of conductivities of neat polymers used in this study. For each polymer blend, electrical conductivities are measured in two directions (i.e.. Directions I and II in Fig. 12.2) to determine whether the specimen is isotropic or not. It is found that there is large difference in conductivity between Directions I and II. For the CNT-filled PET/PVDF, PET/PP, and PET/HDPE, the conductivity in Direction I is about 4-8 times higher than that in Direction II. For the CNT-filled PET/nylon 6,6, the conductivity difference in the two directions is even larger, with Direction I having more than 22 times higher conductivity than Direction II. The anisotropy found in all the specimens is related to the partial alignment of carbon nanotubes in the... 

Table 12.4 Electrical conductivities of CNT-filled polymer blends and neat polymers...

It is also noticeable that even though aU the polymer blends have the same CNT concentration of 6.0 vol%, different polymer blends display different conductivities. The highest conductivity obtained from the CNT-filled PET/PVDF in Direction I is 2.8-5.4 times of the highest conductivities obtained from other CNT-filled polymer blends in Direction I. The better conductivity obtained from the CNT-filled PET/PDVF blend in comparison with the CNT-filled PET/PP and PET/HDPE blends is attributed to its less CNT transfer to the second polymer phase. Such reasoning is supported by the following analysis. 

Given that all of the CNT-filled polymer blends in this study are prepared with 50 vol% of the CNT-filled PET phase (with 12 vol% CNTs) plus 50 vol% of the second immiscible polymer phase (with no CNTs), it is reasonable to assume that both the CNT-fiUed PET phase and the second immiscible neat polymer phase have formed self-continuous 3D networks in the polymer blends. This expectation is confirmed by the microstructure examination (see Sect. 12.1), which reveals that the area fractions of the CNT-filled region and the CNT-free region are both near 50%. Furthermore, the electrical conductivity data suggest that the carbon nanotubes within the PET phase have also formed a 3D conductive path because the electrical resistivity has been reduced from the neat polymer blends to the CNT-filled polymer blends by about 12 orders of magnitude. With such a triple-continuous structure, the conductive CNT-filled PET network and the non-conductive second polymer phase can be treated as parallel conductors, and the resulting resistivity, p, of the CNT-filled polymer blend can be estimated using the statistical percolation model proposed by Bueche [61] ... 

Finally, it is important to compare the electrical conductivities of the CNT-filled polymer blends with that of the CNT-filled polymers. Figure 12.7 shows the resistivities of the CNT-filled PET/PVDF and CNT-filled PET as a function of the carbon... 

To address the issues of the manufacturing cost and concurrent reduction in mechanical properties when a high fiUer concentration is used, carbon-filled polymer blends containing a triple-continuous structure in 3D space have been pursued recently [24-26]. Shown in Fig. 12.1 is the schematic of the carbon-filled polymer blend with a triple-continuous structure, consisting of a binary polymer blend (i.e.. Phases A and B) and CB or CNT particles. Both polymer phases are continuous in 3D space. The conductive carbon is preferentially located in Hiase A and its concentration is... 

Furthermore, binary CNT-filled poly aery lie composite system was introduced in the belief that a miscible polyacrylic blends attract host materials where CNTs could be inserted, since this kind of mixtures has a degree of mixing down to the molecular level (Nie et al. 2012). For example, CNTs contain composite materials films, which were obtained after evaporating the solvent used to prepare solutions of the four t3q>es of binary polymer blends of poly[ethylene-co-(acrylie acid)]. The evidence of H-bond formation was verified for the composite materials (Antolin-Ceron et al. 2008). The Young s moduli and crystallinity of the CNTs-fiUed poly [ethylene-co-(acrylic acid)] composites were improved compared to single polyacrylic. 

In what follows, the major results obtained from the previous studies [24-26] are described first. Then the underlying principle for controlling the distribution of CNTs in the polymer blends is presented, which is followed by discussion of the mechanisms responsible for the simultaneous improvements in the electrical conductivity and mechanical properties observed in the CNT-filled PET/PVDF blends. Finally, future directions in this emerging area are presented. 

Chapter 12 deals with carbon nanotube (CNT) fiUed membranes for PCMs. CNT-filled polyethylene terephthalate was blended with various polymers, injection molded and characterized by different methods. 

Keywords Solar cells, organic photovoltaics (OPVs), quantum confinement effect (QCE), conjugated polymers, nanocomposites, blends, quantum dots (QDs), nanocrystals, nanorods, carbon nanotubes (CNTs), graphene, nanoparticles, alternating copolymers, block copolymers, exdton diffusion length, short-circuit current, open-circuit voltage, fill factor, photoconversion efficiency, in-situ polymerization... 

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