Flame-Retardant and Mechanical Properties of High-Density Rigid Polyurethane Foams Filled with Decabrominated Dipheny Ethane and Expandable Graphite

The article reported the flame-retardant and the mechanical properties of expandable graphite (EG), an intumescent type, and decabrominated dipheny ethane (DBDPE), a gas-phase type of flame-retardant-containing high-density rigid polyurethane foams (RPUF) with a constant density of 0.5g/cm(3). The results indicated that both EG and DBDPE could effectively interdict the burning of RPUF, besides, the EG exhibited more effective flame retardancy than the DBDPE. When the flame-retardant loadings were 20 wt %, the LOI value of DBDPE-filled RPUF increased to 33 vol %, while, surprisingly, the EG-filled RPUF reached 41 vol %. Unfortunately, when they were both simultaneously added into RPUF, there was not any flame-retardant synergistic effect. Although EG had outstanding flame retardancy, the compressive strength and modulus of 20 wt % EG-filled RPUF dropped to only 9.1MPa and 229.7MPa respectively, which were lower than those of DBDPE (12.4 MPa and 246.8 MPa). The phenomena were ascribed to the different flame-retardant mechanisms of EG and DBDPE, which were verified by scanning electronic microscope (SEM) observation of the burned surfaces. Besides, the dynamical mechanical analysis (DMA) demonstrated that the additions of EG and DBDPE made the glass transition temperature shift to the high temperatures, and the EG-filled RPUF had the higher storage modulus. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2372-2380, 2009