Clay-thermoplastic nanocomposites

In the early 1990s, Toyota researchers reported nylon-6-clay thermoplastic nanocomposites [176-178] and observed significant improvements in the mechanical properties (i.e., the modulus was doubled and the increase in strength was more than 50%) at 4.2 wt% clay loading. This inspired many research groups to extend their work on the formation of nanocomposites in many other polymer systems. Silicone rubber (SR) is one of the important functional elastomers and its properties such as high moduli, increased heat resistance, decreased gas permeability and flammability, etc., can be further improved by incorporating different dimensional nanofillers for their better performance in multifaceted applications. 

Several researchers seek to design materials with high performance, greater efficiency, low costs, and lower overall automotive weight, resulting in reduced fuel consumption and CO2 emissions. Most car parts are composed of plastic composite materials. Chevrolet Impalas contain doors with thermoplastic polyolefin nanocomposite. General Motors and BaseU published the application of clay/polyolefin nanocomposites as a step assistant component for GMC Safari and Chevrolet Astro vans in 2001 [61-63]. 

Ale Alessi, S., Conduruta, D., Pitarresi, G., Dispenza, C., Spadaro, G. Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends Thermal, mechanical and morphological behaviour. Polym. Degradation Stability 96 (2011) 642-648. llAsi Asif, A., Rao, V. L., Ninan, K. N. Preparation, characterization, thermo-mechanical, and barrier properties of exfoliated thermoplastic toughened epoxy clay ternary nanocomposites. Polym. Adv. Technol. 22 (2011) 437 47. 

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. 

Flame retardant intumescent formulations have been developed using charring polymers PA6, thermoplastic polyurethanes (TPUs), and hybrid clay-PA6 nanocomposites as carbonisation agents. The advantage of the eoncept is to obtain FR polymers with improved mechanical properties and to avoid the problem of migration and solubility of the additives. 

In the chapter Dispersion of Inorganic Nanoparticles in Polymer Matrices Challenges and Solutions, the synthesis, properties, and applications of nanoparticles their surface modification and preparation of polymer-inorganic nanocomposites are reviewed in detail. The chapter Recent Advances on Fibrous Clay-Based Nanocomposites reviews recent results on nanocomposite materials derived from the fibrous clay silicates sepiolite and palygorskite and combined with diverse types of polymers, from typical thermoplastics to biopolymers such as polysaccharides, proteins, lipids, and nucleic acids. The chapter Nanohybrid Materials by Electrospinning highlights recent progress and current issues in the production of... 

Asif A., Rao V. L. and Ninan K. N. (2011), Preparation, Characterization, Thermomechanical, and Barrier Properties of Exfohated Thermoplastic Toughened Epoxy Clay Ternary Nanocomposites. Po/yw. Adv. Technol, 22,437-47. 

One-step reactive foaming is typical for thermoset polymers. A good example is PU/cIay nanocomposite foams [14,15], where a physical blowing agent, such as pentane, is mixed with monomers and clay nanoparticles. Reaction exotherm leads to a tanperature jump and foaming. Most thermoplastic nanocomposite foams, to date are synthesized via a two-step process the nanocomposite is synthesized first and followed by foaming. 

This method is the only viable route to prepare nanocomposites for most thermoset polymers [15]. Linking interactions between the monomer, the surfactant, and the clay siuface, exfoliated nanocomposites have been successfully synthesized via the ring-opening polymerization, for example epoxy, nylon-6 and polycarbonate. The functional group in the organic cation can catalyze the intralayer polymerization and facilitate layer separation. Many thermoplastic nanocomposites have been synthesized by free radical polymerization. Efforts have been made to anchor initiators in the interlayer region to improve the intralayer polymerization rate for exfoliated nanocomposites [15, 74]. 

Many different polymers have already been used to synthesize polymer-clay nanocomposites. In this section, an overview of the advances that have been made during the last 10 years in the intercalation and the delamination of organoclay in different polymeric media is given. The discussion mainly covers the work involving thermoset nanocomposites along with a brief discussion about thermoplastic-based nanocomposites. 

Chen, B., Evans, J. R. G. (2005). Thermoplastic starch-clay nanocomposites and their characteristics. Carbohydrate PolymerSs 61 s 455 63. 

The FR properties of polymer-layered silicate nanocomposites have been studied for a wide range of polymers, especially for organomodified montmorillonites (OMMT) in thermoplastics. Depending on the nature of the polymer, the decomposition pathway and decomposition products may change.8 A major consequence of the introduction of modified clays is the formation or the enhancement of charred structure, caused by cross-linking processes possibly catalyzed by the nanoparticles. 

GM recently put into production a new nanocomposite made from thermoplastic olefin with a clay filler. Only about 2 percent clay is used, compared with 20 to 30 percent talc in the composite material it replaces. Two advantages of this new nanocomposite are that it is both light-weight and recyclable. Presently, this nanocomposite is used in the step assist for the full-sized van, but a future goal is to use it in body applications such as vertical and horizontal panels. 

General Motors R D and Montell U.S.A. have developed thermoplastic olefin (TPO) clay nano composites with reduced weight and good dimensional stability for exterior automotive applications [24]. PE nanocomposites have also been made effectively by ethylene homo- and copolymerization in the presence of organoclays (see Chapter 5), catalyzed with methylalnminoxane (MAO)-activated zirconocene, nickel, and palladium catalysts [25]. 

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