Comparison with conventional polymer composites

Details of vegetable oil-based polymers conventional composites have been discussed in an earlier chapter. In this chapter, nanocomposites of vegetable oil-based polymers are discussed. Certain questions arise as to how much difference there is between these composites. The questions are significant when the same reinforcing agent is used in both cases. As an example, a vegetable oil-based polyurethane with alkali-treated chopped jute fibres in a conventional composite and cellulose nanofibres (obtained from jute fibres) in a vegetable oil-based polymer nanocomposite are discussed. The 

Light weight Retained Lost and became heavier 

Barrier property Improved greatly Negligible improvement 

Flame retardency Improved greatly Little improved 

The basic differences between vegetable oil-based polymer composites and nanocomposites are given in Table 11.1. 

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Abstract This chapter describes vegetable oil-based polymer nanocomposites. It deals with the importance, comparison with conventional composites, classification, materials and methods, characterisation, properties and applications of vegetable oil-based polymer nanocomposites. The chapter also includes a short review of polymer nanocomposites of polyester, polyurethanes and epoxies based on different vegetable oils and nanomaterials. The chapter shows that the formation of suitable vegetable oil-based polymer nanocomposite can be considered to be a means of enhancing many of the desirable properties of such polymers or of obtaining materials with an intrinsically new set of properties which will extend their utility in a variety of advanced applications. Vegetable oil-based shape memory hyperbranched polyurethane nanocomposites can be sited as an exampie of such advanced products. 

In general, when compared with the conventional polymer composites, polymer nanocomposites exhibit significant improvements in different properties at relatively much lower concentration of filler. The efficiency of various additives in polymer composites can be increased manyfold when dispersed in the nanoscale. This becomes more noteworthy when the additive is used to address any specific property of the final composite such as mechanical properties, conductivity, fire retardancy, thermal stability, etc. In case of polyolefin/LDH nanocomposites, similar improvements are also observed in many occasions. For example, the thermal properties of PE/LDH showed that even a small amount of LDH improves the thermal stability and onset decomposition temperature in comparison with the unfilled PE [22] its mechanical properties revealed increasing LDH concentration brought about steady increase in modulus and also a sharp decrease in the elongation at break [25]. While in this section, fire-retardant properties and electric properties of polyolefin/LDH nanocomposite were described in detail. 

There have been attempts to use metal oxide-CB composites for gas sensor design (Liou and Lin 2007). However, such an approach does not give any improvement in operating characteristics in comparison with conventional metal oxide or CB-polymer-based gas sensors. 

Abstract This chapter describes the influence of three-dimensional nanofillers used in elastomers on the nonlinear viscoelastic properties. In particular, this part focuses and investigates the most important three-dimensional nanoparticles, which are used to produce rubber nanocomposites. The rheological and the dynamic mechanical properties of elastomeric polymers, reinforced with spherical nanoparticles, like POSS, titanium dioxide and nanosdica, were described. These (3D) nanofillers in are used polymeric matrices, to create new, improved rubber nanocomposites, and these affect many of the system s parameters (mechanical, chemical, physical) in comparison with conventional composites. The distribution of the nanosized fillers and interaction between nanofUler-nanofiUer and nanofiller-matrix, in nanocomposite systems, is crucial for understanding their behavior under dynamic-mechanical conditions. 

The thermal and thermomechanical properties of the polymer/HAp composites (glass transition temperature, melting and crystallization behaviour, thermal stability, crosslinking effects, phase composition, modulus, etc.) can be evaluated by thermal analysis methods, like TG, DSC and DMA. Recently, a modulated temperature DSC (MTDSC) technique has been developed that offers extended temperature profile capabilities by, for example, a sinusoidal wave superimposed on the normal linear temperature ramp [326]. The new capabilities of the MTDSC method in comparison with conventional DSC include separation of reversible and non-reversible thermal events, improved resolution of closely occurring and overlapping transitions, and increased sensitivity ofheat capacity measurements [92,327]. 

Generally, nanoeomposites exhibit a significant increase in the properties of polymer matriees, and even yield certain new properties that cannot be derived ifom maero-eomposites or counterparts. The pioneer work of polymer/layered silicate nanoeomposites was reported by Usuki et al. followed by series of reports on this topie. Both intercalated and delaminated nanoeomposites, where layered siUeates were well dispersed within the polymers, resulted in the dramatic enhancement of mechanical, thermal, and barrier performance in comparison with conventional composites. ... 

Polymer layered-silicate day nano-composites (PLCN) attracted lately major interests into the industry and academic fields, since they usually show improved properties with comparison by virgin polymers or their conventional micro and macro-composites. Improvements induded increase in strength, heat resistance (Giannelis, 1998), flammability (Gilman, 2000) and a decrease in gas permeability (Xu et ah, 2001) as well as an increase in biodegradability (Sinha et al., 2002). 

Conventionally, ultra-high molecular weight polyethylene is used for such applications with certain metallic alloys as counterparts. In comparison to this conventional polymer, PEEK and composites of PEEK with carbon fibers show the lowest wear rate on the counter metallic materials. 

Biocomposites consisting of the polymer matrix and natural fibers are environmen-tally-friendly material which can replace glass fiber-reinforced polymer composites, and are currently used in a wide range of fields such as the automotive and construction industries, electronic components, sports and leisure, etc. [1, 2]. Recently, the research on nanobiocomposites which are reinforced with both natural fiber and nanofiller is actively proceeding in order to offer higher thermal and mechanical properties, transport barrier, thermal resistivity and flame retardance in comparison with the conventional biocomposites [3-7]. Recently, nanoclay has become of increasing interest in nanocomposites because the characteristics of nanometer-scaled sihcate pellets, such... 

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