Silica/epoxy nanocomposites

Lia Liang, Y. L., Pearson, R. A. Toughening mechanisms in epoxy-silica nanocomposites (ESNs). Polymer 50 (2009) 4895 905. 

Rag Ragosta, G., Abbate, M., Musto, P., Scarinzi, P., Mascia, L. Epoxy-silica nanocomposites Chemical interactions, reinforcement and fracture toughness. Polymer 46 (2005) 10506-10516. 

Figure 24.4 TEM micrographs of systems containing 15 wt% SiOi, both produced from a bisphenol-A epoxy resin grafted with an amine alkoxysilane-coupling agent (a) epoxy/silica hybrid (cocontinuous domains) and (b) epoxy/silica nanocomposite (particulate silica domains).

Figure 24.5 Comparison of linear expansion as function of temperature of an epoxy resin controi with an epoxy/silica nanocomposite and an epoxy/silica hybrid.

Mascia, L., Prezzi, L., and Haworth, B. (2006) Substantiating the role of phase bicontinuity and interfadal bonding in epoxy-silica nanocomposites. J. Mater. Sci., 41, 1145. 

Liu, Y.L. Hsu, C.Y. Wei, W.L. Jeng, R.J. Preparation and thermal properties of epoxy-silica nanocomposites from nanoscale colloidal silica. Polymer 2003, 44, 5159-5167. 

The same conclusion was presented in a study on amine-cured epoxy-silica nanocomposite film containing 10 % Si02, for which a surface layer containing 75 % silica was determined after long UV exposure intervals [251]. At the same time, no direct evidence was reported for the release of dissociated nanoparticles, although it was suggested that the high accumulation of silica on the surface may, eventually, entail the nanoparticles release. 

HESRNs hybrid epoxy-silica-mbber nanocomposites... 

Wic Wichmann, M. H. G., Cascione, M., Fiedler, B., Quaresimin, M., Schulte, K. Influence of surface treatment on mechanical behaviour of fumed silica/epoxy resin nanocomposites. Compos. Interfaces 13 (2006) 699-715. 

Figure 24.2 Nanostructure of bicontinuous nanocomposites. Top Pictorial description of interconnected organic and inorganic domains with gradient density interphase. Bottom TEM micrograph of an epoxy/silica bicontinuous nanocomposite.

Figure 24.6 Comparison of room-temperature TH F absorption as a function ofimmersion timeof an epoxy resin control with epoxy/silica particulate nanocomposite and epoxy/silica hybrid (bicontinuous nanocomposite).

Figure 24.8 Effects of type of molybdate dopant on the dynamic mechanical properties of epoxy/ silica bicontinuous nanocomposites.

Ihe literature " describes a number of dendrimers and the closely related star-like 120-123 polysiloxanes. Ihe hyperbranched polysiloxanes are the primary example of more random structures. Although the emphasis has been on synthesis and characterization,i i modeling on hyperbranched polymers has also been carried out. Some of the most interesting species involve polysiloxane chains. Star polymers, some with nanosized silica cores, have also been synthesized.i °-i i Hyperbranched polysiloxanes have been prepared with controllable molecular weights and polydispersities,i -1 - with epoxy terminal groups some are UV-curable ° and some serve as a source of molecular silica. Hyperbranched polysiloxanes have also been used in the sol-gel preparation of polypropylene/silica nanocomposites. ... 

Srisuwan S, Thongyai S, Praserthdam P (2010) Synthesis and characterizatirai of low-dielectric photosensitive polyimide/silica hybrid materials. J Appl Polym Sci 117 2422-2427 Tagam N, Okada M, Hira N, Ohki Y, Tanaka T, finai T, Harada M, Ochi M (2008) Dielectric properties of epoxy/clay nanocomposites—effects of curing agent and clay dispersion method. IEEE Trans Diel Electr Insul 15 24—32... 

Liang, Y.L., Pearson, R.A., 2010. The toughening mechanism in hybrid epoxy-silica-rubber nanocomposites (HESRNs). Polymer 51, 4880—4890. 

Liang Y. The toughening mechanism in hybrid epoxy-silica-rnbber nanocomposites. Lehigh University, Bethlehem, PA, USA 2010 p. 20, retrieved 28 March, 2015. 

The depression of the final hmiting fictive temperatures of polycyanurate networks under nanoscale constraint observed in the current study corroborates that the BMDC monomer does penetrate into the nanopores instead of acting as fillers, because the glass transition temperature of the polymer is not expected to be affected when the particles are in micron size as seen in the nanocomposites of epoxy/silica [13] and PMMA/alumina... 

The effect of polymer-filler interaction on solvent swelling and dynamic mechanical properties of the sol-gel-derived acrylic rubber (ACM)/silica, epoxi-dized natural rubber (ENR)/silica, and polyvinyl alcohol (PVA)/silica hybrid nanocomposites was described by Bandyopadhyay et al. [27]. Theoretical delineation of the reinforcing mechanism of polymer-layered silicate nanocomposites has been attempted by some authors while studying the micromechanics of the intercalated or exfoliated PNCs [28-31]. Wu et al. [32] verified the modulus reinforcement of rubber/clay nanocomposites using composite theories based on Guth, Halpin-Tsai, and the modified Halpin-Tsai equations. On introduction of a modulus reduction factor (MRF) for the platelet-like fillers, the predicted moduli were found to be closer to the experimental measurements. 

Hadjistamov (1999) examined the effect of nanoscale silica on the rheology of silicone oil and uncured epoxy-resin (araldite) systems. Shear thickening and yield-stress-like behaviour were observed and found to be due to a build-up of network structure associated with the nanocomposite phase. 

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