The Preparation Of Composite Phase Change Materials And The Temperature Control In The Cigarette Filter

In the process of smoking, high temperature of the cigarette filter not only affects the filtration effect of harmful flue gas, but also affects the consumers’ recognition of cigarette smoking. As far as we know, there are not many research reports about temperature control in cigarette filter. In this paper, according to the special environment of cigarette filter, three types of composite phase change materials were systhesized via different methods. After that, the choosen composite phase change materials were added to cigarette filter. The physical and chemical structure, thermal properties of composite phase change material were characterized by XRD, FT-IR, Nitrogen adsorption-desorption, SEM, DSC and thermal conductivity coefficient detector. We modified the gas phase temperature detection device of cigarette combustion cone, and also analyzed distribution characteristics of filter detection area temperature by the use of analogy in mathematical statistics mathematical expectation and variance of two characteristic. The main contents were as follows:(1)The loaded composite phase change materials were prepared by capillary method, which was conveniently operated and low cost. By investigating 11 kinds of inorganic or organic phase change materials,and 4 kinds of inorganic medium support materials. We dicovered that eicosane was the best phase change material and EG was the best carriermaterial. When quality content of eicosane was 92%, the phase transition temperature of eicosane/EG was 43.1oC, the phase change enthalpy was162.9 J/g, the thermal conductivity was 1.304 W/m·K, which was 3.8times of the pure eicosane. In a word, the eicosane/EG had high latent heat and good thermal conduction performance, and there was no leakage in the process of phase change.(2)In order to improve the reusability of phase change materials, the encapsulated composite phase change materials were prepared via sharp hole-solidification bath method, eicosane as core material, sodium alginate and chitosan as wall materials, calcium chloride as crosslinking agent. Results showed that the optimum preparation process was as below:2.0 wt% sodium alginate solution, 1.5 wt% chitosan solution, 2.5 wt%calcium chloride solution, 93% eicosane, reaction temperature 45 oC,stirring speed 400 r/min, reaction time 90 min, p H ≈ 4. Under the optimal conditions, the phase transition temperature of the prepared microencapsulated phase change materials was 47.9oC, phase change enthalpy was 134.6 J/g, the thermal conductivity was 0.426 W/m·K. In particularly, after 10 cycles of thermal cycling, the phase change temperature was 47.1oC and the phase change enthalpy was 131.4 J/g respectively, which showed that the abtained encapsulated phase change materials had good phase transition properties and repeated stability.(3)Three kinds of imidazoles ionic liquid were designed andsynthesized due to their non-volatilization and phase transformation characteristics. The thermal storage properties of ionic liquids and supported ionic liquids were studied. The results showed that[C16MIM]Cl had better phase transition performance, in detail, the phase transition temperature was 68.1oC, the phase transition enthalpy was129.2 J/g. In addition, the supported ionic liquid [C16MIM]Cl/SBA-15 not only had the same phase transition performance as [C16MIM]Cl, but also had the better repeated stability than [C16MIM]Cl.(4)We established a detection method to test the temperature distribution in cigarette filter tip. In detail, volume averaged temperature as the main index, volume mean temperature difference as the auxiliary indexes, we investigated the tip temperature distribution and the effects of composite phase change materials.For the different weight phase change materials, the temperature field distribution of the filter’s cross section and longitudinal section, volume average temperature and volume mean temperature difference were analyzed and discussed. Results showed that when 40 mg composite phase change materials were added into the cigarette filter tip, the minimum filter volume average temperature and lower mean temperature difference were obtained, which showed the optimal temperature control effect.