The highest value of the relation of the heat release rate and duration FIGRA = 249.6 W/s.
The best fire resistance properties were demonstrated by WPB impregnated with fire retardant solution, the fire growth rate (FIGRA) and the entire amount of heat released of which were almost 2.5 times lower than that of a non-impregnated board.
5 and 6) show also that the addition of the plain bentonite to the epoxy resin formulation leads to a worse flame behavior than the pristine resin: both R-Bento-3 and -5 show, indeed, a higher peak heat release rate (pHRR) and an increment of heat release rate (HRR), fire propagating index (FPI), and fire growth rate index (FIGRA).
The addition of Bento-BFTDA nanofillers, both at 3 and 5 wt%, leads to a significant improvement of the flame retardant properties (pHRR, FPI and FIGRA) of the nanoeomposites if compared with plain R-Bento, but they are still worse than plain resin (NEAT): the N-rich BFTDA is not enough to compensate the negative influence that the clay imparts in terms of flame behavior.
The presence of Bento-APUA leads also to a decrease of both FPI and FIGRA indexes (Figs.
The APUA-containing nanocomposites show instead an encouraging decrease of 17% and 29%, in the Peak Heat Release Rate (pHRR) with respect to the plain resin (NEAT) and to the plain R-BENTO-3, respectively, with just a 3%wt loading level; moreover a reduction of both FPI and FIGRA indexes, an overall sign that the material tends to be less prone to propagating the fire is observed.
PHRR TTI [t.sub.PHRR] Sample (kW [m.sup.-2]) (s) (s) 70/30 (w/w) EVA/wax 851.8 43 268 65.8/28.2/6 (w/w) EVA/wax/EG 544.6 46 203 94/6 (w/w) EVA/EG 610.2 56 278 FPI MLR (a) (kW [m.sup.-2] Sample [s.sup.-1]) (g [s.sup.-1]) 70/30 (w/w) EVA/wax 19.8 0.86 65.8/28.2/6 (w/w) EVA/wax/EG 11.8 0.16 94/6 (w/w) EVA/EG 10.9 0.18 FIGRA
ASEA (kW [m.sup.-2] ([m.sup.2] Sample [s.sup.-1]) [kg.sup.-1]) 70/30 (w/w) EVA/wax 3.2 119.2 65.8/28.2/6 (w/w) EVA/wax/EG 2.7 444.4 94/6 (w/w) EVA/EG 2.2 357.9 (a) Peak values from MLR curves in Fig.
The fire growth rate (FIGRA = PHRR/time to PHRR) displayed the order: EP > EP/5%TPPMMT > EP/5%TPPMMT/10%CP > EP/10%CP > EP/15%CP.
Changes in fire properties such as fire load, the effective heat of combustion, smoke, and CO production were rather insignificant, whereas the PHRR and FIGRA were reduced impressively.
The fire growth rate index (FIGRA) (23) was also listed in Table 3, which was calculated by dividing the peak heat release rate by time to peak heat release (TTPH), giving a unit of kW/[m.sup.2]s.
Other parameters such as THR/TML and FIGRA tabulated in Table 4 were not reduced by the addition of PP-g-MAH.
Sample TTI TTPH PURR THR THR/ (s) (s) (kW (MJ TML (MJ [m.sup.-2]) [m.sup.-2]) [m.sup.-2]) PP/OMMT 36 131 600 75 3.6 [+ or -] [+ or -] [+ or -] [+ or -] 1 2 16 4 PP/PP-g- 36 129 599 80 3.9 MAH/OMMT [+ or -] [+ or -] [+ or -] [+ or -] 1 2 18 3 PP/BER/ 33 134 455 50 2.4 AO [+ or -] [+ or -] [+ or -] [+ or -] 1 2 14 2 PP/PP-g- 39 153 485 56 2.4 MAH/BER/ [+ or -] [+ or -] [+ or -] [+ or -] AO 1 2 13 2 Sample FIGRA (kW [m.sup.-2] PP/OMMT 4.6 PP/PP-g- 4.6 MAH/OMMT PP/BER/ 3.3 AO PP/PP-g- 3.2 MAH/BER/ AO Structure Evolution During Combustion