Thermosetting nanocomposites, cure

In this article we describe the distinguishing characteristics of thermosetting materials the more common thermosetting resins including their cure chemistry thermoset nanocomposites cure and properties, including cure kinetics the development of residual stress as a result of curing cure monitoring and conclude with a description of selected thermoset processes. 

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. 

In this article, recent developments in the formation and properties of epoxy layered silicate nanocomposites are reviewed. The effect of processing conditions on cure chemistry and morphology is examined, and their relationship to a broad range of material properties elucidated. An understanding of the intercalation mechanism and subsequent influences on nanocomposite formation is emphasized. Recent work involving the structure and properties of ternary, thermosetting nanocomposite systems which incorporate resin, layered silicates and an additional phase (fibre, thermoplastic or rubber) are also discussed, and future research directions in this highly active area are canvassed. 

The thermal stability of some thermosetting nanocomposites obtained by thermal cationic cure of diglycidilether of bisphenol A and y-valerolactone using rare earth metal triflates (trifluoromethanesulfonate) as initiators and containing different types of Cloisite was studied. The addition of clay into the polymeric matrix was found to increase the thermal stability, acting as a superior insulator and mass transport barrier to the volatile products evolved during thermal decomposition [67]. 

Zabihi, O., Hooshafza, A., Moztarzadeh, F., Payravand, H., Afshar, A., Alizadeh, R. Isothermal curing behavior and thermo-physical properties of epoxy-based thermoset nanocomposites reinforced with Fe203 nanoparticles. Thermochim. Acta 527, 190-198 (2012)... 

Early, in situ radical polymerization was used for the synthesis of poly(methyl methacrylate) (PMMA)-CNT composites [82]. In situ polymerization was performed using the radical initiator 2,2-azobisisobutyronitrile(AIBN). In this reaction, p-bonds in CNTs were initiated by AIBN, and therefore nanotubes could participate in PMMA polymerization to form a strong interface between the CNT and the PMMA matrix. PA6/CNT composites have been prepared by in situ polymerization of e-caprolactam in the presence of pristine and carboxylated CNTs. The e-caprolactam monomer was found to form an electron-transfer complex with CNTs and result in a homogeneous, polymerizable solution. The final composites can be spun into PA6/CNT fibers (Fig. 7) with excellent mechanical and electrical properties [83].This method is also suitable for the fabrication of thermosetting polymer composites with nanofillers. Bauhofer et al. [84] dispersed CNTs in an epoxy solution system based on a bisphenol-A epoxy resin and an amine hardener During nanocomposite curing, electric fields were used to induce the formation of aligned conductive nanotube networks. Recently, the in situ polymerization method... 

Report 162 Analysis of Thermoset Materials, Precursors and Products, Martin J. Forrest, Rapra Technology Ltd Report 163 Polymer/Layered Silicate Nanocomposites, Masami Okamoto, Toyota Technological Institute Report 164 Cure Monitoring for Composites and Adhesives, David R. Mulligan, NPL... 

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. 

Jin and Park processed the Al O -epoxy nanocomposites by hot curing technique [69]. Zheng et al. prepared the SiO -epoxy nanocomposites by mixing the nanoparticles in epoxy matrix at 120°C [4]. Similarly, SiO -based thermoset polyester nanocomposites are prepared by mechanical mixing followed by ultrasonication [72]. Alumina-epoxy nanocomposites are also processed in-situ by reducing the size of alumina particles from micrometer range to nanometer range with the assistance of mechanical vibrator [73]. 

For bulk materials, Jin et al fabricated poly (methylmethacrylate) (PMMA)/MWNT nanocomposites by melt mixing. MWNTs were well dispersed in the matrix [90]. Melt compounding is also widely used for the fabrication of composite fibers. Sandler et al mixed polyamide-12 pellets and CNTs in a twin-screw micro-extruder and then the extrudate was chopped and fed into a capillary rheometer with 1 mm die. The CNTs in the spun fibers were uniformly dispersed [91]. Not only can thermoplastic polymers be melt-compounded, polyimide, a thermoset plastic, can be also prepared by mixing the imide oligomer at 320 °C on a steel plate and then cured at 370°C. It was found that the dispersion of CNTs in... 

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