导热填料改性烟草颗粒的热解和释烟特性

为揭示加热不燃烧状态下导热填料对烟草颗粒热解和释烟特性的影响规律，利用导热系数测试仪、热分析仪（TGA）和锥形量热仪（CONE），研究了不同含量和种类的导热填料对烟草颗粒导热系数、热解过程以及烟气释放过程的影响。结果表明:①随碳酸钙（CaCO₃）粉体质量分数增加，烟草颗粒导热系数增大。20%添加量下填料发生自团聚，导热系数略有降低。晶须可有效改善填料在基材中的自团聚现象。碳化硅（SiC）较CaCO₃对导热系数的提升更明显。②相较于对照样品，添加导热填料后，烟草颗粒微分热重（DTG）曲线向低温区移动，整体上导热性越高，移动幅度越大，最大失重速率越大。不同升温速率下，具有最大导热系数样品的DTG曲线始终位于对照样的低温侧；且随升温速率增大，其与对照样热解特征参数的差值逐渐缩小，导热性差异对烟草颗粒热解过程的影响程度减小。③相较于对照样品，添加导热填料后，烟草颗粒起始释烟速率增大；随导热性提高，最大释烟速率增大，烟气释放过程集聚。CO与CO₂的释放速率随导热性提高明显增大，说明烟草颗粒的热解程度加剧，但提高导热性易造成热量集聚，使烟草颗粒发生燃烧。 

Pyrolysis and smoke release characteristics of tobacco granules modified with thermally conductive filler

In order to investigate the effects of thermally conductive fillers on the pyrolysis and smoke release characteristics of tobacco granules under heating and non-combustion conditions, a thermal conductivity tester, a thermogravimetric analyzer (TGA) and a cone calorimeter (CONE) were used to study the influences of thermally conductive fillers of different contents and types on the thermal conductivity, pyrolysis and smoke release of the prepared tobacco granules. The results showed that: 1) With the increase of CaCO₃ powder content, the thermal conductivity of tobacco granules increased. The thermal conductivity decreased slightly due to self-aggregation of the filler when the CaCO₃ addition reached 20%. Whiskers could effectively restrain the self-aggregation of the fillers in the substrate. The effects of SiC on thermal conductivity were more significant than CaCO₃. 2) Compared with the control, the differential thermal gravity (DTG) curve of the tobacco granules shifted towards the low temperature region after adding thermally conductive filler. The higher the thermal conductivity of the filler, the larger the curve shifting range and the higher the maximum weight loss rate were. Under different heating conditions, the DTG curve of the sample with the largest thermal conductivity was always on the low temperature side of the control. With the increase of heating rate, the difference of the pyrolysis characteristic parameters between the sample and the control reduced gradually, and the effects of thermal conductivity difference on the pyrolysis process of tobacco granules lessened. 3) Compared with the control, the initial smoke release rate of the tobacco granules increased after adding thermally conductive filler; the maximum smoke release rate increased with the increase of thermal conductivity, and the smoke release was aggregated. The release rates of CO and CO₂ increased significantly with the increase of the thermal conductivity of the filler, indicating that the pyrolysis degree of tobacco granules was enhanced. However, the promotion of the thermal conductivity could easily cause heat accumulation and tobacco granule combustion.