Nanocomposite thermosets

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. 

PP-g-MA) silicate nanocomposites and intercalated thermoset silicate nanocomposites for flame-retardant applications were characterised by XRD and TEM [333], XRD, TEM and FTIR were also used in the study of ID CdS nanoparticle-poly(vinyl acetate) nanorod composites prepared by hydrothermal polymerisation and simultaneous sulfidation [334], The CdS nanoparticles were well dispersed in the polymer nanorods. The intercalation of polyaniline (PANI)-DDBSA (dodecylbenzene-sulfonate) into the galleries of organo-montmorillonite (MMT) was confirmed by XRD, and significantly large 4-spacing expansions (13.3-29.6A) were observed for the nanocomposites [335],... 

Analysis of Thermoset Materials, Precursors and Products, Martin J. Forrest, Rapra Technology Ltd. Polymer/Layered Silicate Nanocomposites, Masami Okamoto, Toyota Technological Institute. 

Fig. 11 In situ formation of amine nucleophiles and a,/S-unsaturated carboxamides that react further in thermosetting of hyperbranched dendrimer-polyanhydride nanocomposite thin films...

Incorporation of modified clays into thermosetting resins, and particularly in epoxy35 or unsaturated polyester resins, in order to improve thermal stability or flame retardancy, has been reported.36 A thermogravimetric study of polyester-clay nanocomposites has shown that addition of nanoclays lowers the decomposition temperature and thermal stability of a standard resin up to 600°C. But, above this temperature, the trend is reversed in a region where a charring residue is formed. Char formation seems not as important as compared with other polymer-clay nanocomposite structures. Nazare et al.37 have studied the combination of APP and ammonium-modified MMT (Cloisite 10A, 15A, 25A, and 30B). The diluent used for polyester resin was methyl methacrylate (MMA). The... 

Zammarano, M. 2007. Thermoset fire retardant nanocomposites. In Flame Retardant Polymer Nanocomposites, Eds. A. Morgan and C. Wilkie, New York John Wiley Sons. 

Many studies have used these methods for processing of both thermosetting and thermoplastic polymers. Y. Liao (53) dissolved epoxy in a well-dispersed, ultra-sonicated CNT suspension. The solvent was evaporated, and the epoxy was subsequently cured to form a nanocomposite in which the good CNT dispersion was achieved. Jin et al. (54) produced various types of polymer-coated and polymer-grafted MWNT solutions, in some cases evaporating the solvent and subsequently melt-mixing with another polymer. Yudasaka et al. (55) used a mixture of SWNTs and PMMA in monochlorobenzene (MCB) for dispersion, purification and subsequent spin-casting of the material. 

Another area of current research is development of nanocomposites. Incorporation of nanometer-sized fillers in thermosets allows even broader application of thermoset technology. The processing techniques are quite similar to conventional thermosets, but the... 

As discussed earlier, while the scale of the fillers is substantially different, nanocomposite materials concepts and technology are very similar to those of conventional composite materials. This is clearly demonstrated in the case of new thermosets for nonlinear optical (NLO) applications, " " where nanocomposite of liquid crystalline thermosets, IPNs, and simple filled thermosets are evaluated. Tripathy et al. discussed four different ways to prepare nonlinear optical polymers. (1) The polymer matrix is doped with NLO moieties in a guest/host system (2) In side-chain polymer systems, NLO polymers with active moieties are covalently bonded as pendant groups (3) In the main chain polymer, the chromo-phores are incorporated as parts of the main polymer backbone to enhance the temporal stability of the NLO properties and (4) Stability of the optical noninearity in sol-gel-based thermosets is related to... 

Much work has been reported on studying the structure of thermoset resins via SAXS, especially focussing on interpenetrating network polymers (IPNs), thermoset nanocomposites, rubber-modified thermosets and thermoset-thermoplastic blends. Most recently Guo et al, (2003) have examined the use of SAXS to monitor the nanostructure and crystalline phase structure of epoxy-poly(ethylene-ethylene oxide) thermoset-thermoplastic blends. This work proposes novel controlled crystallization due to nanoscale confinements. 

Scanning electron microscopy (SEM) involves scanning an electron beam (5-lOnm) across a surface and then detecting the scattered electrons. Literature abounds, with work focussing on the use of SEM in the fracture and failure of epoxy resins and other thermoset polymers. Also work on multiphase thermosets (thermoset-thermoplastic blends, thermoset nanocomposites, interpenetrating network (IPN) polymers) is abundant. 

Polymeric nanocomposites are a class of relatively new materials with ample potential applications. Products with commercial applications appeared during the last decade [1], and much industrial and academic interest has been created. Reports on the manufacture of nanocomposites include those made with polyamides [2-5], polyolefins [6-9], polystyrene (PS) and PS copolymers [10, 11], ethylene vinyl alcohol [12-15], acrylics [16-18], polyesters [19, 20], polycarbonate [21, 22], liquid crystalline polymers [8, 23-25], fluoropolymers [26-28], thermoset resins [29-31], polyurethanes [32-37], ethylene-propylene oxide [38], vinyl carbazole [39, 40], polydiacethylene [41], and polyimides (Pis) [42], among others. 

Battisti, A., Skordos, A.A., and Partridge, I.K. 2009b. Dielectric monitoring of carbon nanotube network formation in curing thermosetting nanocomposites. J. Phys. D Appl. Phys. 42 55402. 

The introduction of nanoceramics in thermoplastics or thermosets seems to be a promising route to improving mechanical moduli, particularly of elastic matrices. The macroscopic properties are governed by the nature of polymer-nanoparticle interactions. In this chapter, specific attention will be paid to nanocomposites of polyamide (PA) with HAp. Considering their attractive viscoelastic properties, semiaromatic polyamides (e.g., PA-llTlO) have been chosen as the matrix [Choe et al., 1999]. Recently, several publications have been devoted to one-dimensional nanostructures with high-aspect-ratio particles. Promising data have been obtained for the polymer/nanowire-nanotube nanocomposites. 

Before discussing the flow behavior of polymeric nanocomposites (PNCs), the nature of these materials should be outlined. As the name indicates, PNCs must contain at least two components, a polymeric matrix with dispersed nanoparticles [Utracki, 2004]. PNCs with thermoplastics, thermosets, and elastomers have been produced. The nanoparticles, by lUPAC s definition, must have at least one dimension that is not larger than 2 nm. They can be of any shape, but the most common for structural PNCs are sheets about 1 nm thick with the aspect ratio p=D/t= 20 to 6000, where D is the inscribed (or equivalent) diameter and t is the thickness of the sheet. These inorganic lamellar solids might be either natural or synthetic [Utracki et al., 2007]. 

An interesting novel RP development that differs fi-om what has been occurring involves special nanotechnology used to reinforce plastics. The Business Communications Co., Inc., Norwalk, CT reported that total worldwide sales during 2003 of plastic nanocomposites were 90.8 million with about 78% thermoplastic and 22% thermoset. By 2008 sales should reach 211 million with about 90% thermoplastic and 10% thermoset. 

Processing and characterization of new thermoset nanocomposites based on cellulose whiskers, 7,117-131. 

Ruiz, M.M., Cavaille, J.Y., Dufresne, A., Gerard, J.F., Graillat, C. Processing and characterization of new thermoset nanocomposites based on cellulose whiskers. Compos. Interfaces 7, 117-131 (2000)... 

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