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    Flame retardant systems based on alkoxysilanes for wood protection
    (Intech, 2017) Giúdice, Carlos Alberto; Canosa, Guadalupe
    The aim of this study was to formulate, develop, and determine the performance of flame-retardant systems for wood protection. Flame-retardant systems involve wood impregnation and intumescent coating application. The impregnation was made in two retention levels using silanes of low and high hydrophobicity (methyltriethoxysilane and n-octyltriethoxysilane, respectively); these silanes were conducted to polymerize by sol-gel process in wood pores. The intumescent coatings were formulated with a polymeric binder (hydroxy-functional acrylic resin) modified with n-octadecyltriethox- ysilane in two w/w ratios to combine the individual characteristics of each film-forming material. In this research, Pinus radiata panels were selected to study the performance of quoted flame-retardant systems. The results indicated excellent flame-retardant performance of some studied systems in two foot tunnel, in oxygen index cabin, and in horizontal-vertical chamber.
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    Performance of wood impregnated with alkoxysilanes
    (REHABEND, 2016-05-24) Canosa, Guadalupe; Alfieri, Paula; Giúdice, Carlos Alberto
    The wood, very heterogeneous and complex material, changes its volume by water absorption or desorption causing swelling or shrinkage and also it can be degraded both by action of microorganisms and fire; the above-mentioned is a great inconvenient for most commercial uses. Solid wood specimens of Araucaria angustifolia were impregnated with alkoxysilanes hydrolyzed and condensed “in situ” by the sol-gel process. Alkoxysilanes selected were aminopropyl methyldiethoxysilane and aminopropyl triethoxysilane; it was also used the aminopropyl methyldiethoxysilane/aminopropil triethoxysilane mixture in 50/50 w/w ratio. The pH was adjusted to alkaline value for controlling kinetic of hydrolysis and condensation reactions. Impregnation process was carried out at 45–50 oC in an autoclave, controlling the operating conditions for achieving different weight gains. Unmodified and modified wood specimens were exposed to brown rot (Polyporus meliae) and white rot (Coriolus versicolor) under laboratory conditions. The results indicate that the improved resistance to fungal exposure would be based on the wood c emical modification (t e protection of cellulose caused by steric indrance of i-O-Cellulose preventing the formation of enzyme-substrate complex). Moreover, the results also would be based on the enhanced dimensional stability of the treated wood; the quoted high dimensional stability, which limits the growth of the spores, is supported in the hydrophobicity generated by both the decreasing of the amount of polar hydroxyl groups and the partial occupation of pores with polysiloxanes. Fire laboratory tests were carried out in Two-Foot Tunnel (flame spread index, panel consumption and smoke density) and in TGA detector (mass loss). The performance can be explained according the reactivity of the alkoxides; the results indicate that as weight gain increase the performance of impregnants against fire also does.