Polymer nanocomposites polyurethane

Fabrication methods have overwhelmingly focused on improving nanotube dispersion because better nanotube dispersion in polyurethane matrix has been found to improve the properties of the nanocomposites. The dispersion extent of CNTs in the polyurethane matrix plays an important role in the properties of the polymer nanocomposites. Similar to the case of nanotube/solvent suspensions, pristine nanotubes have not yet been shown to be soluble in polymers, illustrating the extreme difficulty of overcoming the inherent thermodynamic drive of nanotubes to bundle. Therefore, CNTs need to be surface modified before the composite fabrication process to improve the load transfer from the polyurethane matrix to the nanotubes. Usually, the polyurethane/CNT nanocomposites can be fabricated by using four techniques melt-mixing (15), solution casting (16-18), in-situ polymerization (19-21), and sol gel process (22). 

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. 

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... 

A large number of vegetable oil-based polymer nanocomposites have been reported in the literature. Among these, vegetable oil-based polyesters, polyurethanes and epoxies are very important and are discussed in the following sub-sections. 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

Martin DJ, Osman AF, Andriani Y, Edwards GA (2012) Thermoplastic polyurethane (TPU)-based polymer nanocomposites. In GaoF(ed) Advances in polymer nanocomposites types and applications. Woodhead, Cambridge, pp 321-350... 

Metal/polymer nanocomposites were prepared by Chen and co-workers (55) using dispersion of metal chlorides in polyurethane. Both pol5nirethane and metal salts were dissolved in iV,A( -dimethylacetamide, followed by film casting and reduction of the metal salts by sodium borohydrate. The metal particle size depended on the type of metal salt used and on its concentration. 

Inorganic-polymer nanocomposites characterized by exceptional dielectric constant are often called artificial dielectrics . Artificial dielectrics are created when isolated particles become polarized due to the presence of an applied electric field. These novel nanocomposite artificial dielectrics have the potential to posses high dielectric constants (>100) at high frequencies and the low processing temperature associated with polymers. Such a combination of properties is not found in other capacitor materials [180]. Polymer matrices like PMMA, poly(vinylidene fluoride) (PVDF), PS, and polyurethane (PU) have been used. Owing to their physicochemical properties, they represent suitable polymer components for embedding nanoscopic functional inorganic fillers (Table 2). 

Few examples of nanocomposites in which the cellulosic nanostructure is used in biobased thermosets can be also foimd. Due to the fact that these environment friendly composites suffer from several limitations, such as low mechanical properties due to low strength in reinforcement plus inadequate interfacial strength, and that cellulose nanostructures have been shown to have significant potential as a reinforcement, the possibility of using cellulose nanofibers as reinforcements in a bio-derived resin was revised. In Masoodi et al. [200], cellulose nanofibers were used as reinforcements in the forms of layered films, while in Lee et al. [201] the stability of the gas-soybean oil foam templates and the mechanical properties of the polymer nanocomposite foams are enhanced upon the addition of bacterial cellulose nanofibrils. Other examples of biobased thermosets containing cellulosic nanoreinforcements are the work of Shibata [202] in which the use of a biobased epoxy was revised, and systems in which cellulose nanocrystals are incorporated in biobased polyurethanes [203,204], Few examples exist also in the literature on the polymerization of furfuryl alcohol in presence of CNR [205,206] in these papers, the authors established the feasibility of producing furfuryl... 

It should be emphasized that the molecular theories presented in this chapter are valid only for flexible homopolymers and thus they cannot describe the rheological behavior of stmctured polymer systems, including multicomponent and/or multiphase polymers, such as block copolymers, liquid-crystalline polymers, thermoplastic polyurethanes, immiscible polymer blends, highly filled polymers, and nanocomposites. We discuss this subject in the remaining chapters of this volume. 

Let us consider the estimation methods of parameters included in Equation 7.17. The value of was accepted to be equal to the value of Q for polyurethanes PTMG and PBAD. As it is known [30], in the polymer nanocomposites case actually the nanofiller and interfacial regions of the particles surrounding it with relative fractions (p and respectively, will be impenetrable for diffusion. Then the polymer matrix relative fraction a can be estimated as follows [56] ... 

The results were compared with a standard steel sample which was tested either in the as-received condition or coated with a layer of lubricating grease. In addition to the modification of stmctural composites a number of polymer nanocomposites were made by mixing nanoscale reinforcements with a polyurethane resin. In this case the resin was again cast against a glass... 

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