Clay reinforcement thermal properties

In this chapter, the methods of producing clay-polymer nanocomposites are discussed in detail. The influence of clay reinforcement on the mechanical, thermal and physical properties of thermoplastic and thermosetting polymers is also discussed. This chapter also comprises of processing techniques of polymer nanocomposites using nanoparticles hke Al O, CaCO, TiO, ZnO and SiO as reinforcements. These materials have the potential to alter tribological, electrical and optical properties considerably. 

Clay minerals, in NR, have a remarkable effect on (i) rheological properties, (ii) vulcanization efficiency, (hi) barrier properties, (iv) mechanical reinforcement, (iv) thermal properties, (v) degradation properties, (vi) flame resistance. 

Chen F, Lou D, Yang J, Zhong M (2011) Mechanical and thermal properties of attapulgite clay reinforced polymethylmethacrylate nanocomposites. Polym Adv Technol 22 1912-1918... 

General discussions of the effect of reinforcing agents on the thermal properties of polymers include glass fiber-reinforced polyethylene terephthalate [28], multiwalled carbon nanotube-reinforced liquid crystalline polymer [29], polysesquioxane [30, 31], polynrethane [31], epoxy resins [32], polyethylene [33], montmorillonite clay-reinforced polypropylene [34], polyethylene [35], polylactic acid [36, 37], calcium carbonate-filled low-density polyethylene [38], and barium sulfate-filled polyethylene [39]. 

For clay-reinforced nanocomposites, increases in modulus compared with the unfilled polymer matrix have been observed in many systems with the effect increasing with filler content as expected but the properties are highly sensitive to microstructure (Luo and Daniel, 2003). In general, to maximise stiffness (and thermal properties) it is necessary to achieve fiiU exfoliation and dispersion which is not readily achieved (Vu etal., 2001, Zhang etal., 2004). 

The huge variety of nanocomposite materials containing versatile nanofillers offers a wide range of potential applications. Depending on the specific properties of the nanofiller, the polymer materials may be reinforced chemical and thermal stability can be enhanced or completely new electrical, ferroelectric, magnetic, or diverse optical properties may be introduced to the material. Since the reinforcement of polymers is taking an immense research field including CNT composite materials and clay nanocomposites, the mechanical properties of these composite materials have been discussed elsewhere extensively. Hierefore, this contribution will focus on optical and thermal properties of nanocomposite and hybrid materials. 

Exfoliated nanoscale layered silicate particles have been seen to provide dramatic improvements in mechanical properties in polyamide systems [1]. Numerous studies have since attempted to achieve the same degree of reinforcement in an array of thermoset and thermoplastic polymer systems [2]. Layered silicate clays have been popular due to low cost, high surface area, and versatility of organic treatments available to make them compatible with a host of commercial polymer systems [3]. These clays are natmally available as tactoid structures consisting of several silicate layers stacked in crystalline lattice [4,5]. However, optimum reinforcement and improvement in thermal properties are obtained when tactoids are exfoliated into individual platelets [1-3,6-24]. 

S-H. Wu, F-Y. Wang, C-C.M. Ma, W-C. Chang, C-T. Kuo, H-C. Kuan, and W-J. Chen, Mechanical, thermal and morphological properties of glass fiber and carbon fiber reinforced polyamide-6 and polyamide-6/clay nanocomposites, Mater. Lett., 49, 327-333 (2001). 

Incorporating fillers or reinforcing agents is another means of improving polymer properties. High particulate loadings improve the dimensional stability of electronic circuit boards so that the thermal expansion is greatly reduced. Particulate fillers (talc, mica, silica, clay, etc.) are used... 

Polymer matrix nanocomposite is the most important type of nanocomposite in which the performance of a polymer matrix can be enhanced by appropriately adding nanoparticulates to it [12] and good dispersion of the filler can be achieved [ 12]. A imiform dispersion of nanoparticles leads to a very large matrix/filler interfacial area, which changes the molecular mobility, the relaxation behavior and the consequent thermal and mechanical properties of the material. A polymer matrix could be reinforced by much stiffer nanoparticles [13,14] of ceramics, clays, or carbon nanotubes, etc. Recent research on thin films (thickness < 50 micrometer) made of polymer nanocomposites has resulted in a new and scalable synthesis technique increasing the facile incorporation of greater nanomaterial quantities [15]. Such advances will enable the future development of multifunctional small scale devices (i.e., sensors, actuators, medical equipment), which rely on polymer nanocomposites. 

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