Physical characterization of the cigarette coal Part II. Puff burn

The morphologies of the tobacco and coal char of the puff-burned cigarettes were characterized using light microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The cigarettes were smoked with either a 35 or 70 cm(3) puff volume and stopped 1s into the fourth puff with nitrogen gas. The morphology and elemental content were characterized from four regions within the cigarette coal; the ash, coal tip, coal base, and charred tobacco under the char line. Shred morphologies under the char line ranged from minimal surface change to melting of the cuticle, to internal vesicle formations, to tubular and irregular rod formations. These rod-shaped structures were found throughout the coal but not in the ash. In the coal base and coal tip regions, the morphologies ranged from minimally charred tobacco to shreds covered with vesicles, to carbonized shreds encrusted with inorganic crystals to partially oxidized shreds. The ash consisted of carbonized shreds to oxidized shreds of reticulate networks of inorganic crystals. Shred morphologies observed in the coal regions of the 70 cm(3) puff volume were similar to those seen from the coal regions of the 35 cm(3) puff volume, but a little more extreme with more extensive vesicle formations and more extensive tube formations. Elemental analyses showed that sodium, potassium, sulfur, and phosphor-us were partially lost to the smoke stream in the coal base and coal tip. In the ash, sulfur, sodium, potassium, phosphorous, and magnesium were reduced. Carbon and nitrogen decreased in the ash while hydrogen decreased continuously from the control unburned tobacco, to the coal base, the coal tip, and the ash. Oxygen content in the unburned control tobacco decreased in the coal base with minimal to no decrease in the coal tip then a slight increase in the ash. (C) 2004 Elsevier B.V. All rights reserved.