The Preparation Of The Controlled-release Material Of The NH₃Applied In The Agents Supervision Instrument And Study On The Properties Of Composites

Due to the excellent binding force of protons and easily identified spectral lines, ammonia is often used as carried gas of ion mobility spectrometry, which carries samples into the instrument, so as to achieve the purpose of separation and detection. Previous studies show that ammonia could be produced by anhydrous ammonia treatment and decomposition of ammonium salt. The former treatment is done by sealing ammonia in a stainless steel jar, then the ammonia could release through the permeable membrane. While the later treatment is that ammonium salt decomposes in a semi-transparent device and releases ammonia through permeable membrane. Both methods have their advantages and disadvantages, which limit their use in micro-portable IMS instrument.In this thesis, a new method was designed to produce ammonia with ammonia delivery materials which are mainly used for monitoring the type and concentration of toxic gases in IMS system. The Ammonia released from ammonia delivery materials could improve the sensitivity and accuracy of the agents’supervision instrument.The new ammonia delivery material developed in this thesis was using room temperature vulcanization silicone rubber as matrix and ammonium bicarbonate as an active agent dispersed in the matrix, the fumed silica was also added for the purpose of reinforcing matrix. The effects of types of silastic, amount of ammonium bicarbonate and the fumed silica, kneading time and temperature on the accumulating and releasing concentration of ammonia released from ammonia delivery material were studied in this thesis. It has been showed that:(1) the ammonia delivery material made from706RTV silicone rubber, bicarbonate ammonium, the fumed silica which plays as the matrix, active agent, reinforcing agent respectively, could effectively control the release of ammonia. When the kneading time is1h and the amount of the fumed silica is2.0-2.5g in lOg silicone rubber, the ammonia delivery material shows the optimal performance.(2) The release rate of ammonia increases as the temperature increases. The temperature on one hand affects the decomposition of ammonium bicarbonate, on the other hand affects the diffusion of ammonia.(3) The mechanical properties of ammonia delivery material is strengthened by adding the fumed silica, and increases as the amount of the fumed silica increases in certain extent. The tensile strength of ammonia delivery material within2.5g the fumed silica is as high as1.6MPa, which is5times out of the material without the fumed silica. In addition, the hardness of material with the fumed silica is5times more than that of material without the fumed silica.In this thesis, the stability and concentration of ammonia released from ammonia delivery material are measured by simulating the agents’ supervision instrument, which turns out that:The samples prepared under ventilation exhibits stable dynamic release rate and excellent performance. At room temperature, for achieving stable slow release feature (about0.6-0.8ppm) and meeting the requirement of instrument, the optimal concentration of ammonia delivery material is below:10g706room temperature vulcanization silicone rubber,1g ammonium bicarbonate,2.0g the fumed silica and1h kneading time.