Nanocomposites carbon-based nanofillers

The effects of carbon-based nanofillers of EG, MWCNTs, and CNFs on the AC conductivity and dielectric constant of elastomeric grade EVA (50% vinyl acetate content) at a particular frequency of 12 Hz, are shown in Fig. 29a, b [194]. EVA-EG, EVA-T, and EVA-F represent EVA-based nanocomposites reinforced with EG, MWCNT, and CNF respectively. 

Graphene-polymer nanocomposites share with other nanocomposites the characteristic of remarkable improvements in properties and percolation thresholds at very low filler contents. Although the majority of research has focused on polymer nanocomposites based on layered materials of natural origin, such as an MMT type of layered silicate compounds or synthetic clay (layered double hydroxide), the electrical and thermal conductivity of clay minerals are quite poor [177]. To overcome these shortcomings, carbon-based nanofillers, such as CB, carbon nanotubes, carbon nanofibers, and graphite have been introduced to the preparation of polymer nanocomposites. Among these, carbon nanotubes have proven to be very effective as conductive fillers. An important drawback of them as nanofillers is their high production costs, which... 

Table 8.5 EMI SE properties of polymer nanocomposites with carbon based nanofillers... 

Recent works in liquid crystalline polymer science, also emphasises more on the use of Thermotropic Liquid Crystalline Polymers (TLCPs) for development of nanocomposites using different nanofillers (Cheng et al. 2012). A discussion has already been made on this in the foregoing discussions. Carbon based nanofillers are more promising in this regards. 

Carbon-based polymer nano composites represent an interesting type of advanced materials with structural characteristics that allow them to be applied in a variety of fields. Functionalization of carbon nanomaterials provides homogeneous dispersion and strong interfacial interaction when they are incorporated into polymer matrices. These features confer superior properties to the polymer nanocomposites. This chapter focuses on nanodiamonds, carbon nanotubes and graphene due to their importance as reinforcement fillers in polymer nanocomposites. The most common methods of synthesis and functionalization of these carbon nanomaterials are explained and different techniques of nanocomposite preparation are briefly described. The performance achieved in polymers by the introduction of carbon nanofillers in the mechanical and tribological properties is highlighted, and the hardness and scratching behavior of the nanocomposites are also discussed. 

Table 10.2 presents a summary of the properties reviewed in this chapter according to the type of carbon nanofillers used. The enhancements provided by these nanomaterials are diverse indicating that there are still many challenges for explaning the structure-property relationships of carbon-based polymer nanocomposites. 

Electrical conductivity is the attribute of the carbon-based nanofiUers that makes them highly suitable for electronic applications. GO is intrinsically insulating due to the presence of oxygen-containing functional groups, but the removal of such groups makes GO suitable to manufacture of conducting nanocomposites. From the different methods discussed previously for reduction of GO, the chemical and thermal routes are most commonly used to restore the electrical conductivity of GO nanofillers before their incorporation into a polymer matrix. Polymer composites with chemically and/ or thermally reduced GO were reported to display electrical percolation thresholds as low as 0.2% vol. in various studies as depicted in Table 8.4. 

The most common nanofUlers are inorganic oxides and carbon based nanofUlers with different geometries. We will concentrate on the Si02 nanoparticle and multiwall carbon nanotube (CNT) here. Both types of fillers exhibit rather poor compatibility with the hydrophobic LCER, so they have to be chemically modified with appropriate chemical functionality for LCER. The chemical functimiality on the nanofiller can bond with the resin either by van der Waal forces or chemical bonds. The former is called heterogeneous nanocomposite and the latter is called homogeneous nanocomposite. 

So, that using similar polymerization approach several conducting polymer nanocomposites (with different polymers like polypyrrole (PPy), poly(phenylene-diamine) (PPD), and poly(3,4-ethylene dioxythiophene) (PEDOT, etc.) have been developed using CNT as nanofillers and various conductive polymer as a matrix. Some of them are reported in other literature [46,49-51]. Ramesh and coworker [51] synthesized very useful nanoclays and conducting carbon-based nanocomposites for supercapacitor application. The procedure is briefly discussed below. 

The chapter deals with a brief account of various topics in polyethylene-based blends, composites and nanocomposites. We discuss the different topics such as ultra high molecular weight polyethylene (UHMWPE) for orthopaedics devices, stabilization of irradiated polyethylene by the introduction of antioxidants, polyethylene-based conducting polymer blends and composites, polyethylene composites with hgnocellulosic material, LDH as nanofillers of nanocomposite materials based on polyethylene, ultra high molecular weight polyethylene and its reinforcement/oxidative stability with carbon nanotubes in medical devices, montmorillonite polyethylene nanocomposites, and characterization methods for polyethylene based composites and nanocomposites. 

Nanocomposites based on other nanofillers like metal oxides, hydroxides, and carbonates... 

Carbon materials provide electrical conduction through the pi bonding system that exists between adjacent carbon atoms in the graphite structure [182]. Electrical properties of nanocomposites based on conducting nanofillers such as EG [183-187], CNTs [188-190], and CNFs [191], dispersed in insulating polymer matrix have found widespread applications in industrial sectors. 

Bhattacharyya, A Sreekumar, T. liu, T. Kumar, S. Ericson, L. Hauge, H. Smalley, R. (2003) Crystallization and Orientation Studies in Polypropylene/Single Wall Carbon Nanotube Composite. Polym. Vol.44, N0.8, pp.2373-2377, ISSN 0032-3861 Bilotti, E. Fischer, H. Peijs, T. (2008) Polymer nanocomposites based on needle-like sepiolite clays Effect of functionalized polymers on the dispersion of nanofiller, crystallinity, and mechanical properties, f. Appl. Polym. Sci. Vol.107, No.2 pp.lll6-1123, ISSN 0021-8995... 

This is Volume 2 of Natural Rubber Materials and it covers natural rubber-based composites and nanocomposites in 27 chapters. It focuses on the different types of fillers, the filler matrix reinforcement mechanisms, manufacturing techniques, and applications of natural rubber-based composites and nanocomposites. The first 4 chapters deal with the present state of art and manufacturing methods of natural rubber materials. Two of these chapters explain the theory of reinforcement and the various reinforcing nanofillers in natural rubber. Chapters 5 to 19 detail the natural rubber composites and nanocomposites with various fillers sueh as siliea, glass fibre, metal oxides, carbon black, clay, POSS and natural fibres ete. Chapters 20-26 discuss the major characterisation techniques and the final ehapter covers the applications of natural rubber composites and nanoeomposites. By covering recent developments as well as the future uses of rubber, this volume will be a standard reference for scientists and researchers in the field of polymer chemistry for many years to come. 

NR composites and nanocomposites can be fabricated by three main techniques, namely latex compounding, solution mixing and melt blending. A variety of nanofillers, such as carbon black, silica, carbon nanotubes, graphene, calcium carbonate, organomodified clay, reclaimed rubber powder, recycled poly(ethylene terephthalate) powder, cellulose whiskers, starch nanocrystals, etc. have been used to reinforce NR composites and nanocomposites over the past two decades. In this chapter, we discuss the preparation and properties of NR composites and nanocomposites from the viewpoint of nanofillers. We divide nanofillers into four different types conventional fillers, natural fillers, metal or compound fillers and hybrid fillers, and the following discussion is based on this classification. 

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