Nanocomposites polyurethane

TABLE 9.3 Cone Calorimeter Data at 25 kW/m for PP-GF Laminates Coated with 1 mm of Nanocomposite Formulation (Nanocoat) or Standard Microformulation (Microcoat)  

FIGURE 9.29 Residue after a cone calorimeter test of laminate PP-GF coated 1 mm thick on the left side a standard epoxy-APP formnlation (microcoat), and on the right side an LDH modified formulation (nanocoat). (Conrtesy of Consorzio CETMA, Italy.) 

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J.Y. Kwon, H.D. Kim, Preparation and properties of acid-treated multiwalled carbon nanotubes/waterborne polyurethane nanocomposites, Journal of Applied Polymer Science, vol. 96, pp. 595-604, 2005. 

Y. I. Tien and K. H. Wei, High-tensile-property layered silicates/polyurethane nanocomposites by using reactive silicates as pseudo chain extenders, Macromolecules 34, 9045-9252 (2001). 

Modesti, M. Lorenzetti, A. Besco, S. Hrelja, D. Semenzato, S. Bertani, R. Michelin, R.A.. Synergism between flame retardant and modified layered silicate on thermal stability and fire behaviour of polyurethane nanocomposite foams. Polym. Degrad. Stab. 2008, 93, 2166-2171. 

Ye. P. Mamunya, V. I. Shtompel, E. V. Lebedev, P. Pissis, A. Kanapitsas, and G. Boiteux, Structure and water sorption of polyurethane nanocomposites based on organic and inorganic components, Eur. Polym. J. 40, 2323-2331 (2004). 

Melt processing is a common alternative that is particularly useful for dealing with thermoplastic polymers and holds great interest because of the ease with which the process could be scaled up to industrial standards. Thermoplastic polyurethane nanocomposites can be fabricated by melt compounding of CNTs with polymer resin. Melt processing makes use of the fact that thermoplastic polymers soften when heated. Amorphous polymers like elastomer... 

Several main synthesis methods widely applied to produce carbon nanotube-polyurethane nanocomposites were summarized above. In addition, latex technology (27), thermally induced phase separation (28), electrospinning (29,30) and many other methods also show their own advantages and promises, however, these methods will not be discussed here. 

It is difficult to fully utilize the mechanical or electrical properties of CNTs in their polyurethane nanocomposites due to the difficulty... 

The viscoelastic properties of carbon nanotube/polymer composites have both practical importance related to composite processing and scientific importance as a probe of the composite dynamics and microstructure. The viscosity for CNT/PU dispersion at mixing is also very important for in-situ formation of polyurethane nanocomposite. Lower viscosity means a better flow ability and more homogenous mixing with isocyanate. Furthermore, low viscosity is very helpful to remove the bubbles before curing, which is a key step for polyurethane preparation. 

The unique two-phase structures of polyurethane that offers the elasticity of rubber combined with the toughness and durability of metal make them one of the most extensively studied and frequently used materials in carbon nanotube related nanocomposites. The main difficulty in developing CNT based polyurethane nanocomposites was how to achieve uniform and homogeneous CNT dispersion. Further investigations on the interactions between carbon nanotubes and two-phase structures are critical for the wider applications of carbon nanotube/polyurethane composites. 

S. Dutta, N. Karak, J. P. Saikia and B. Konwar, Biocompatible epoxy modified bio-based polyurethane nanocomposites mechanical property, cytotoxicity and biodegradation , Bioresour Technol, 2009,100, 6391-7. 

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. 

The cytocompatibility of polyurethane nanocomposites is generally studied from red blood cell (RBC) haemolysis inhibition data obtained from the anti-hemolytic test described in Chapter 2. In most of the reported cases, vegetable oil-based polyurethane nanocomposites exhibit better haemolysis prevention against harmful free radicals than do their respective pristine polyurethanes. These observations indicate that the presence of nanomaterial in the nanocomposites plays a crucial role in RBC haemolysis prevention. 

Electrical properties such as conductivity, resistivity, I (current)-V (voltage) characteristics of vegetable oil-based polyurethane nanocomposites are sometimes influenced by nanocomposite formation with a suitable nanomaterial. BaTiOs superfine fibre-filled castor oil-modified polyure-thane/poly(methyl methacrylate) interpenetrating polymer network nanocomposites exhibit an increase in conductivity between insulator and semiconductor with an increase in nanofibre loading. ... 

Epoxy-modified Mesua ferrea L. seed oil-based conventional polyurethane nanocomposites prepared by an ex situ solution technique under high mechanical shearing and ultrasonication at room temperature with different (1,2.5 and 5) wt% loadings of clay have been evaluated as biocompatible materials. The partially exfoliated nanocomposites exhibited two- and... 

Images of different states of shape memory MWNT/ hyperbranched polyurethane nanocomposites. 

Tetraethoxyorthosilane and linseed oil polyol silica embedded polyurethane nanocomposites were obtained by a sol-gel technique. The polyol/ silica nanoparticles network showed a strong interaction with uniform, spherical silica nanoparticles of 2-30 nm size embedded in the polymer matrix. The system was further reinforced by 2 wt% and 5 wt% fumed silica. The resultant systems showed improved thermal stability with mild to moderate antibacterial behaviour against E. coli and S. aureus. 

Mechanical properties such as tensile strength, elongation at break, scratch resistance and impact resistance increase with the loading of nanomaterial. The main reasons for this are the same as those described for polyester or polyurethane nanocomposites. The stiffness of the nanomaterial contributes to the presence of immobilised or partially immobilised... 

There are other examples of applications of vegetable oil-based nanocomposites in different fields. These include soybean oil-based PU/silica nanocomposites as surface coating materials, anti-corrosive polyurethane/ OMMT coatings for carbon steel and palm oil, soybean oil and castor oil-based polyurethane nanocomposite as foams. - - - ... 

D. Akram, S. Ahmad, E. Sharmin and S. Ahmad, SUica reinforced organic-inorganic hybrid polyurethane nanocomposites from sustainable resource , Macromol Chem Phys, 2009,211,412-19. 

A.K. Barick, and D.K. Tripathy, Preparation, characterization and properties of acid functionahzed multi-walled carbon nanotube reinforced thermoplastic polyurethane nanocomposites. Materials Science and Engineering B Solid-State Materials for Advanced Technology, 176 (18), 1435-1447, 2011. 

Cao, F. and Jana, S.C. (2007) Nanoclay-tethered shape memory polyurethane nanocomposites. Polymer, 48 (13), 3790-3800. 

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