PEG/SiC对PLA材料改性研究及其在加热卷烟中的应用

  目的  加热卷烟烟支结构较短，入口烟气温度相对传统卷烟较高，需添加降温材料以降低烟气温度。通过对聚乳酸（PLA）材料进行改性处理，以开发出适用于加热卷烟用的降温材料。  方法  采用熔融挤出方法制备聚乙二醇（PEG）/碳化硅（SiC）改性PLA复合材料，利用拉伸机、热重（TG）、差示扫描量热仪（DSC）与加热卷烟吸烟机考察复合材料力学性能、热特性以及对烟气降温效果、关键成分释放的影响。  结果  （1）较纯相PLA而言，添加PEG后复合材料拉伸强度、冲击强度明显下降，熔融指数与断裂延伸率增大，韧性增强；进一步添加SiC后，复合材料断裂延伸率与熔融指数减小。（2）添加PEG后，复合材料起始热分解温度降低，20%添加量下DSC曲线在53.32℃处出现主吸热峰，热焓变化值为48.63 J/g；加入SiC后，该峰热焓变化值减小，主吸热峰转至PLA熔融吸热峰处。（3）逐口烟气温度随PEG含量增加呈明显降低趋势，加入SiC后，复合材料导热系数增大，对烟气降温效果进一步提高；添加改性复合材料后，主流烟气中总粒相物、烟碱、水分、甘油含量降低，CO释放量变化不明显，不同改性样品间各成分释放差异较小。  结论  利用PEG、SiC对PLA进行改性处理，可有效提升对烟气的降温效果。 

Study on PEG/SiC modification of PLA material and its application in heated tobacco

  Background  Heated cigarettes have higher smoke temperature than traditional cigarettes because of shorter stick structure, so cooling materials need to be added to reduce the smoke temperature. In this paper, we developed a cooling material suitable for heating cigarettes by modified polylactic acid (PLA).  Methods  The stretching machine, thermogravimetry (TG), differential scanning calorimeter (DSC), and heated cigarette smoking machine were used to investigate PLA composite materials modified by polyethylene glycol (PEG)/silicon carbide (SiC) in terms of the mechanical properties, thermal properties, cooling effect, and release of key components in the smoke.  Results  (1) Compared with the pure-phase PLA, the composite material had increased fracture elongation and toughness after adding PEG, but the melt index and the resistance to thermal collapse were reduced. After further addition of SiC, the fracture elongation of the composite material decreased and the melt index increased. The toughness was reduced, and the thermal collapse resistance was improved. Compared with pure-phase PLA, the mechanical properties such as tensile strength and impact strength of the composite material decreased significantly after adding PEG. The melt index and elongation at break increased. The elongation at break and the melt index of the composite decreased after further adding SiC. (2) After adding PEG, the initial thermal decomposition temperature of the composite material was reduced, and the main endothermic peak appeared in the DSC curve at 53.32℃ under dosage of 20%, and the enthalpy change value was 48.63 J/g. After the addition of SiC, the variation in enthalpy decreased, while the main endothermic peak shifted to the PLA melting endothermic peak. (3) Compared with pure PLA, the temperature of puff-by-puff flue gas showed a significant decreasing trend with the increase of PEG content. The contents of total particulate matter, nicotine, moisture, and glycerin in mainstream flue gas decreased, whereas the CO release did not change significantly. For the composite material, the thermal conductivity of composite material after adding SiC increased, thus improving cooling effect of the flue gas.. The emissions of total particulate matter, nicotine, moisture, and glycerin content in mainstream flue gas decreased, while the release of CO was almost unchanged compared to the sample without SiC addition. The samples with different dosages of SiC showed insignificant difference in emission amounts.  Conclusion  The results of this study show that the use of PEG and SiC to modify PLA can effectively improve the cooling effect of flue gas.