An Investigation on Synergistic Effect of EG with IFR in Polyethylene
Great concerns with environmental pollutions caused by halogen elements and heavy metals have been driving the development of eco-friendly wire and cable compounds, among which halogen-free low-smoke flame-retardant polyolefins are of great importance. Intumescent flame retardants (IFR) show better efficiency in flame retardant polyolefins (PO) than metal hydroxides, such as magnesium hydroxide and aluminum hydroxide, but the flame retardancy of IFR/PO is still limited. Recently, expandable graphite (EG), a promising eco-friendly flame retardant, has attracted much attention. In the paper, the synergistic effect of expandable graphite (EG) with intumescent flame retardants (IFR) on flame retardant polyethylene (PE) was investigated by limited oxygen index (LOI) and the investigations on the synergistic mechanism were performed by thermogravimetric (TG) and scanning electron microscope (SEM). The results showed that the flame retardant properties of PE/EG/IFR were greatly improved by the synergistic effect of EG with IFR. Compared with the cracking barrier on the combustion surface of PE/EG or PE/IFR, a very thick and compact char layer forming on the combustion surface of PE/EG/IFR was more in favor of preventing the transfer of oxygen and heat, thus leading to lower thermal degradation rate and more char left
Effect of Dolomite Clay on Thermal Performance and Char Morphology of Expandable Graphite Based Intumescent Fire Retardant Coatings
Abstract Dolomite Clay was introduced in a traditional intumescent flame retardant system which contains ammonium polyphosphate/expandable graphite/melamine (APP–EG–MEL) to evaluate its effects on char morphology and fire performance. The effect of dolomite clay on the fire-resistance and thermal properties of expandable graphite based Intumescent fire retardant coatings has been investigated by using Bunsen burner fire test and thermal gravimetric (TG) techniques. The current study describes the effects of Dolomite Clay on the heat shielding performance of intumescent passive fireproofing coatings during fire testing. The fire performance of dolomite clay reinforced intumescent coating formulations were evaluated by Bunsen burner fire test according to ASTM E-119. Results showed that the dolomite reinforcement in IFRC formulation significantly reduced the steel substrate temperature up to 180 °C after 1 hour of fire exposure. The coating degradation was studied using thermogravimetric analysis (TGA). The physical morphology and alignment of intumescent char residue were studied by field emission scanning electron microscopy (FESEM). TGA analysis revealed that IFD (8) containing 8 wt. % of dolomite clay enhanced residual weight by 37.30%. It is suggested that Dolomite clay can enhance the fire performance and can significantly affect the formation of dense and continuous char if incorporated as a filler in conventional intumescent fire resistive systems.
Flammability of GRP for use in ship superstructures
The burning characteristics of glass-reinforced panels with an isophthalic polyester resin, the same resin with an inorganic flame retardant, two differing vinylester resins or a resole phenolic as the matrix were tested at a range of incident heat flux values using a cone calorimeter. The phenolic composite was superior at all levels showing a longer ignition time, reduced heat output, less contribution to a low-level sustained fire (25 kWm−2) and lower smoke yield.