Preparation Of Heat Storage Capsules And Its Influence On Temperature Of Cigarette Filter

Cigarette filter has attracted considerable attention over the past few years,due to its practical function for filtering the nicotine,tar and other harmful components which are simultaneously produced during smoking.However,the temperature of main smoke stream can be as high as 70 to 80 ? during the smoking process which seriously restricts the filtration effect of harmful flue gas as well as the taste of the cigarette.There are still three problems in the practical application of Na2HPO4�12H2O as phase change material:supercooling,easily leaking out during phase transition and the impossibility for adding water directly to the cigarette filter.To overcome the limitations,the Na2HPO4�1H2O-?-Al2O3 composite,Na2HPO4 � 12H2O@poly?lactic acid?capsule and water@poly?lactic acid?capsule phase transition materials were prepared in this thesis.After that,the choosen phase change materials were added to cigarette filter.The main innovative results are listed as follows:1?The influence of the addition amount of the nucleating agent on the degree of supercooling was studied.The results indicated that the degree of supercooling gradually decreases to 1.5 ? at 5%of a-A1203.2?The microcapsulated phase change materials were prepared using Na2HP04�12H2O as the core,and poly?lactic acid?as the shell through a coaxial needle.The thermal properties of microPCMs were characterized by differential scanning calorimetry?DSC?.The optimum preparation process was described as below:poly?lactic acid?concentration 10%,PVA concentration 3%,stirring speed 250 r/min,shell/core flow rate 16 mL h-1/8 mL�h-1.Under the optimal conditions,the particle size of the prepared microencapsulated phase change materials is about 2 mm,phase change enthalpy was 122.2 J/g.3?The water@poly?lactic acid?capsules were prepared using water or hydrophilic aqueous solution as the core,and poly?lactic acid?as the shell through the coaxial needle.The influences of poly?lactic acid?concentration,polyvinyl alcohol concentration,stirring speed and injection rate of core and shell solutions on the particle size and water content of capsules were also investigated.The results indicated that the diameter of the capsule was about 4 mm and the packaged water amount was about 35.3 mg when the concentration of poly?lactic acid?was 15%,the concentration of poly?lactic acid?was 15%,the concentration of polyvinyl alcohol was 3%,the stirring speed was 250 r/min and the shell/core flow rate was 8 mL h-1/5mL h-1.4?The influences of Na₂HPO₄ 12H₂O@poly?lactic acid?and water@poly?lactic acid?phase change capsules on the temperature of the filter tip during the smoking process were respectively investigated using a "cigarette smoking temperature detection system�.The Results showed that when 40 mg phase changing capsules were added into the cigarette filter tip,the temperature could be reduced to less than 35?;when the amounts of water was 35 mg,the temperature could be less than 35?.