The Pore Size Distribution of Naturally Porous Cigarette Paper and its Relation to Permeability and Diffusion Capacity

The pore size distribution of cigarette paper determines its air permeability and diffusion capacity and thereby has a significant influence on the gas exchange of a cigarette through the cigarette paper during smoking and during smouldering. For the design of cigarettes and in particular of cigarette papers it is important to understand how the pore size distribution of the cigarette paper is affected by the paper composition and paper properties and how it influences air permeability and diffusion capacity.

It was the aim of this study to investigate how the composition of the cigarette paper such as filler content, fibre type and burn additive content qualitatively influenced the pore size distribution and how the pore size distribution and, in particular, which pore size range is correlated with air permeability and diffusion capacity, respectively. To this end eight naturally porous cigarette papers were selected which differed in air permeability, diffusion capacity, fibre type, filler content and burn additive content. The pore size distributions of these papers were measured by mercury porosimetry before and after the papers had been heated to 230 °C for 30 min. The pore size distributions were investigated for qualitative differences when air permeability, fibre type and filler content of the cigarette paper are modified. Furthermore by appropriate weighting of the pore size distributions optimal correlations between a weighted pore volume and air permeability or diffusion capacity were determined. The results show a good correlation with correlation coefficients greater than 0.9 for air permeability as well as for diffusion capacity. The results indicate that large pores are better correlated with changes in air permeability, while small pores are more strongly correlated with changes in diffusion capacity and support previous theoretical results obtained from flow and diffusion models. They also demonstrate the tight relationship between pore size distribution, air permeability and diffusion capacity, which makes the pore size distribution a tool to further optimize cigarette papers, for example, with respect to carbon monoxide yields in the smoke of a cigarette. [Beitr. Tabakforsch. Int 26 (2015) 312-319]