Search

The effects of exogenous potassium salts on the thermal degradation of flue-cured tobacco were investigated using thermogravimetric analysis (TGA), surface area/porosity measurements (SAPM), real-time fourier transform infrared (RT-FTIR), and thermogravimetric/Fourier transform infrared spectrometry (TG-FTIR), respectively. TGA analysis showed that potassium salts accelerated tobacco’s degradation at around 150–350 °C, but improved the thermal stability of char residue at high temperature range. The porous texture analysis displayed that potassium salts reduced the pore volume and surface area of tobacco pyrolysis residues. Further study using RT-FTIR illustrated that there was a positive catalysis of potassium salts with C O, O H and C O bonds at different temperature ranges, but a protective effect was given to C H bond, C C bond and aromatic moieties except for the accelerating degradation of C H by the oxidation effect of KNO 3 . The evolution comparison of their gaseous products manifested that potassium salts cut down the emission of CO 2 , H 2 O, CO, aldehydes and alkanes, but enhanced the release of carbonyl compounds, anhydrides and alcohols at around 150–350 °C. Above 350 °C, the potassium salt-containing samples exhibited a gentle escape process for both the oxygen-bearing molecules (CO 2 , H 2 O and CO) and oxygen-free species (alkanes, methane and unsaturated compounds) in comparison with their quick emission for the virgin samples.

In this paper, the quantitative evaluation of CO yields of flue-cured tobacco under the low-temperature heating conditions was investigated using a steady state tube furnace (SSTF) on the basis of controlled equivalence ratio method. Then the effect of temperature, ventilation condition and elemental compositions on the CO yields was studied, respectively. There was a strikingly low CO yield of heated tobacco under a fixed ventilation condition in comparison with flaming or even smouldering tobacco, and the temperature just slightly influenced the CO yield of flue-cured tobacco under the low-temperature heating states. At a fixed temperature of 450 °C, the CO yield, with reducing air velocity, first increased fast and then tended to remain unchanged. The correlation study indicates that there were no significant relationships between CO yields and the individual element except for the content of carbon and hydrogen, while the significant negative correlations of CO yields with the ratio of potassium to sulphur (K/S) at the 0.01 level appeared. Further random-Forest analysis revealed that K/S is another important factor influencing CO yields of fuel-cured tobacco under the externally heated pyrolysis conditions after hydrogen content.

The thermal degradation and flammability of ordinary area (OA) and coating band (CB) of low ignition propensity (LIP) cigarette paper were compared using scanning electron microscopy (SEM), real-time Fourier transform infrared (RT-FTIR), thermogravimetric/Fourier transform infrared spectrometry (TG-FTIR) and microscale combustion calorimeter (MCC), respectively. SEM results showed that only the compactly packed particles, instead of fibers exposed on the surface of OA, could be seen on the surface of CB. And it is at the whole temperature range that there are still many closely packed particles on the surface of CB. The results of thermal degradation displayed that C H and C O bonds in CB displayed higher thermal stabilities than those in OA. And the comparison of the evolution of their gaseous products manifested that the emission of many gas products of CB like methane, hydrocarbons, aldehydes, CO and alcohols were obviously lower than those of OA. Furthermore, some evaporated species like alkanes, CO, carbonyl compounds and alcohols escaped earlier than those of OA. Their flammability results demonstrated that both peak heat release rate (PHRR) and total heat release (THR) of CB above 270 °C in the degradation step of cellulose and the following char decomposition were lower than those of OA.

In this paper, the APP-modified reconstituted tobacco sheet (RTS) was prepared by a paper-making process. Thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG-FTIR) had been used to investigate the influences of APP on the thermal degradation and the formation of evolved volatile products of RTS. TG-FTIR results illustrated that the incorporation of APP into RTS could retard the thermal degradation of the major components of RTS and meanwhile lead to the formation of more thermally stable char. Moreover, the main gases released during the pyrolysis of RTS and APP-modified RTS were H 2 O, CO 2 , CO, NH 3 , carbonyl compounds, alcohols and alkanes. The presence of APP changed the formation of evolved volatile products of RTS obviously. The effects of APP on the combustion behavior of RTS were studied by micro-scale combustion calorimetry (MCC), cone calorimetry (CCO) and infrared thermography (IRT). Results demonstrated that the formation of combustible gases was mainly determined by the thermal decomposition stage occurred in the temperature range of 150–600 °C. The incorporation of APP into RTS influenced the release of fuel gases and the char formation in the process of the thermal decomposition of RTS, and eventually retarded the flammability of RTS. In addition, it had been found that the maximum firecone temperature of untreated RTS was higher than that of APP-modified RTS.

In this paper, the formation mechanism of pyrolysis gases released during the pyrolysis of pectin under the conditions that simulate cigarette smouldering was investigated by thermogravimetric analysis coupled to Fourier transform infrared spectrometer (TG–FTIR). Moreover, the combustion behavior of pyrolysis gases was studied by micro-scale combustion calorimetry (MCC). TG–FTIR results illustrated that the composition of the gaseous products was mainly composed of CO2, H2O, CO, methanol, methane and carbonyl compounds. MCC results demonstrated that the combustion of pectin was mainly determined by the prolysis gases formed in the temperature range of 200–300 °C. Flash pyrolysis experiment in combination with high performance liquid chromatography (FPy–HPLC) was used to study the pyrolytic formation of eight carbonyl compounds (i.e. formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone and butyraldehyde) during the pyrolysis of pectin under the pyrolysis conditions of cigarette puffing. Results demonstrated that pyrolysis temperature influenced the formation of acetaldehyde, acrolein, propionaldehyde and butyraldehyde greatly, while nitrogen flow affected the generation of formaldehyde, acetone, crotonaldehyde and methyl ethyl ketone deeply.