The Class F fly ash has been subjected to high energy ball milling and has been converted into nanostructured material. The nano structured fly ash has been characterized for its particle size by using particle size analyzer, specific surface area with the help of BET surface area apparatus, structure by X-ray diffraction studies and FTIR, SEM and TEM have been used to study particle aggregation and shape of the particles. On ball milling, the particle size got reduced from 60 lm to 148 nm by 405 times and the surface area increased from 0.249 m 2 /gm to 25.53 m 2 /gm i.e. by more than 100%. Measurement of surface free energy as well as work of adhesion found that it increased with increased duration of ball milling. The crystallite was reduced from 36.22 nm to 23.01 nm for quartz and from 33.72 nm to 16.38 nm for mullite during ball milling to 60 h. % crystallinity reduced from 35% to 16% during 60 h of ball milling because of destruction of quartz and hematite crystals and the nano structured fly ash is found to be more amorphous. Surface of the nano structured fly ash has become more active as is evident from the FTIR studies. Morphological studies revealed that the surface of the nano structured fly ash is more uneven and rough and shape is irregular, as compared to fresh fly ash which are mostly spherical in shape.

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Hybrid nanocomposites of styrene butadiene rubber (SBR) with nanostructured fly-ash (NFA) were prepared in the laboratory by melt blending technique in an internal mixer. Curatives were added on a laboratory two-roll mill. Curing characteristics as well as physicomechanical properties of the composites were evaluated. A comparison on SBR composites filled with fresh fly-ash (FFA); carbon black (CB) and precipitated silica (PS) has been reported. In general, SBR-NFA composites exhibit higher state of cure and higher strength properties as compared with HAF black-filled and fresh fly-ash-filled SBR composites at equivalent loadings. This may be attributed to the higher reinforcing ability of NFA. This fact has also been supported by the swelling studies and Kraus' plot. Tear strength and abrasion resistance of the SBR-NFA composites were superior to FFA-filled and precipitated silica-filled vulcanizates, but were inferior to carbon black-filled SBR vulcanizates. The SBR-NFA composites showed lower hardness as compared with both the carbon blackfilled and silica-filled composites. Transmission electron microscopy and scanning probe microscopy studies revealed that the NFA particles are well dispersed in the SBR matrix. These results were further supported by fracture surface analysis under the SEM, which revealed the role of NFA in the prevention of fracture propagation.

ISO 13571:2007 describes the calculation of safe escape time using yields of asphyxiant and irritant gases for performance based design. Hydrogen chloride (HCl) gas is an incapacitating irritant, reported to be intolerable at concentrations above 100 ppm, but lethal to rats only at concentrations around 5000ppm for a 30 minute exposure. It is evolved from burning PVC, and other chlorine containing plastics. The experimental evidence of the concentration/dose effects on a range of animal species has been reviewed, and concludes that the HCl concentration leading to incapacitation of 1000 ppm, used in ISO 13571, is rather too high to ensure safe escape. Experimental data is presented from burning unplasticised PVC, plasticized PVC cable, and LDPE to show that HCl interferes with the flame chemistry, particularly the conversion of CO to CO 2 , further increasing the hazard from the fire effluent. The product yields are used to estimate the fire effluent toxicity, comparing the standard based on rat lethality, ISO 13344 with the newer standard, which also takes the effect of incapacitating irritants into account, showing the large contribution of HCl to the fire hazard. Finally, the relationship between the toxicity and a simple analysis of effluent acidity (EN 50297-2-3) is discussed.