Effect of incorporation of POSS compounds and phosphorous hardeners on thermal and fire resistance of nanofilled aeronautic resins

Abstract

The aim of this work is the identification of the best strategy for improving thermal, fire resistance and electrical conductivity of an epoxy resin for aeronautic applications. The effect of DodecaPhenyl POSS (DPHPOSS), Epoxycyclohexyl POSS (ECPOSS), Glycidyl POSS (GPOSS) and TriglycidylCyclohexyl POSS (TCPOSS) to act as flame retardants of the resin was evaluated. Flame retardancy tested by the limiting oxygen index (LOI) indicated that GPOSS has meaningful effects on the flame retardancy of the epoxy mixture. The incorporation of 5 wt% of GPOSS into the epoxy matrix resulted in a LOI value of 33 with respect to 27 of the pure epoxy mixture. The trend observed by LOI tests was confirmed by mass loss calorimetry measurements: a decrease from 540 kW m-2 down to 327 kW m-2 was observed in the peak of heat release rate (PHRR). LOI and PHRR values were compared with those obtained for the same resin replacing the 4,4′-diaminodiphenyl sulfone (DDS) with the bis(3-aminophenyl) phenylphosphineoxide (BAPPO) and the bis(3-aminophenyl) methyl phosphine oxide (BAMPO). BAMPO and BAPPO proved to be more effective than POSS compounds to increase LOI values. Carbon nanotubes (CNTs), embedded inside the epoxy resin to enhance electrical conductivity, are found to affect significantly fire properties of epoxy systems mainly by preventing the epoxy systems from forming intumescent charring

Fatigue behaviour of innovative multifunctional epoxy resins

“…The selected MWCNT concentration was of 0.5% (by wt). 4 The GPOSS compound was dispersed at a percentage of 5 wt% in the epoxy matrix. 18 An ultrasonication for 20 min has been used in order to achieve a uniform dispersion of 0.5% (by wt) MWCNTs within the epoxy matrix.…”

“…Multi walled carbon nanotubes (MWCNTs) and polyhedral oligomeric silsesquioxanes (POSS) are common additives to produce polymers with improved electrical conductivity as well as fire resistance [1][2][3][4] ; both features are very important for the aircraft structures as well as for several applications where safety is a concern, as boats, offshore, etc. Multi walled carbon nanotubes (MWCNTs) and polyhedral oligomeric silsesquioxanes (POSS) are common additives to produce polymers with improved electrical conductivity as well as fire resistance [1][2][3][4] ; both features are very important for the aircraft structures as well as for several applications where safety is a concern, as boats, offshore, etc.…”

“…6 Raimondo et al 4 studied the flame retardancy properties of enhanced epoxy systems with 5 wt% POSS compounds by measuring the limiting oxygen index (LOI) and the peak heat release rate (PHRR). Polyhedral oligomeric silsesquioxane (POSS) are hybrid inorganic/organic compounds with an inner inorganic core, which is occupied by the silicon and oxygen components and external organic substituents that make them compatible with most polymers.…”

Flame retardant and toughening mechanisms of core–shell microspheres

“…Recently, many eco-friendly flame retardants have been developed to improve the flame retardancy of EP, involving phosphorous-, nitrogen-, silicon-, phosphorous-/nitrogen-containing compounds and inorganic nanofillers (montmorillonite and aluminum hydroxide et al) [6][7][8][9][10] .…”

Epoxy Resin/POSS Nanocomposites with Toughness and Thermal Stability

“…For instance, the PLA/POSS composites were prepared and modulus and elongation at break values improved at low (1% and 3%) POSS loading levels [10]. Raimondo et al has reported that incorporation of 5 wt% of glycidyl POSS into the epoxy matrix resulted in a limiting oxygen index value of 33 with respect to 27 of the pure epoxy mixture [11] .…”