In the last years there has been a considerable interest in a new class of materials, known as organic–inorganic (O-I) hybrids, which present unique characteristics arising from the combination of organic and inorganic components. Recently, epoxy-based O-I hybrids, consisting of epoxy resins with interpenetrating silica domains, have been optimized by the authors. The methodology for their production is based on the sol-gel technology, involving the hydrolysis and condensation of metal alkoxides in aqueous solution, which is able to bind chemically, at nanometric scale, the organic phase with the inorganic one. These novel hybrid systems present superior properties then those of the parent resins. The presence of nanostructured co-continuous organic and inorganic domains, in fact, allows to achieve higher glass transition temperatures, greater mechanical properties and enhanced adhesion to different substrates than those experienced by epoxy resins. Thanks to their peculiarities, these epoxy-based hybrid systems have been investigated by the authors as potential “cold-cured” adhesives, i.e. to be cured at ambient temperature and to be used in Cultural Heritage for restoration of artefacts and consolidation of masonry structures. The main interest in cold-cured epoxy-silica hybrids lies, in fact, in the possibility of overcoming the main limitations of conventional cold-cured epoxy resins, currently used as adhesives and matrices for FRP (Fiber Reinforced Plastics) in the restoration and repair of ancient masonry structures. They require, in fact, long curing times, while, due to the incomplete cure, the glass transition temperature (Tg) of the final products can only achieve values about 10-20°C higher than the temperature used for the curing process. Moreover, the Tg of cold-cured epoxies can decrease to even lower values through the absorption of water, due to plasticization phenomena caused by strong association of OH of water with NH groups of the epoxy. The aim of this chapter is to analyse the properties of the organic–inorganic epoxy-based hybrid systems, highlighting their potential as efficient, structural and non-structural, adhesives for Cultural Heritage.
Organic-inorganic epoxy-based hybrids as potential adhesives for Cultural Heritage consolidation
LIONETTO, Francesca;FRIGIONE, Mariaenrica
2013-01-01
Abstract
In the last years there has been a considerable interest in a new class of materials, known as organic–inorganic (O-I) hybrids, which present unique characteristics arising from the combination of organic and inorganic components. Recently, epoxy-based O-I hybrids, consisting of epoxy resins with interpenetrating silica domains, have been optimized by the authors. The methodology for their production is based on the sol-gel technology, involving the hydrolysis and condensation of metal alkoxides in aqueous solution, which is able to bind chemically, at nanometric scale, the organic phase with the inorganic one. These novel hybrid systems present superior properties then those of the parent resins. The presence of nanostructured co-continuous organic and inorganic domains, in fact, allows to achieve higher glass transition temperatures, greater mechanical properties and enhanced adhesion to different substrates than those experienced by epoxy resins. Thanks to their peculiarities, these epoxy-based hybrid systems have been investigated by the authors as potential “cold-cured” adhesives, i.e. to be cured at ambient temperature and to be used in Cultural Heritage for restoration of artefacts and consolidation of masonry structures. The main interest in cold-cured epoxy-silica hybrids lies, in fact, in the possibility of overcoming the main limitations of conventional cold-cured epoxy resins, currently used as adhesives and matrices for FRP (Fiber Reinforced Plastics) in the restoration and repair of ancient masonry structures. They require, in fact, long curing times, while, due to the incomplete cure, the glass transition temperature (Tg) of the final products can only achieve values about 10-20°C higher than the temperature used for the curing process. Moreover, the Tg of cold-cured epoxies can decrease to even lower values through the absorption of water, due to plasticization phenomena caused by strong association of OH of water with NH groups of the epoxy. The aim of this chapter is to analyse the properties of the organic–inorganic epoxy-based hybrid systems, highlighting their potential as efficient, structural and non-structural, adhesives for Cultural Heritage.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
