Papers by Keyword: DMMP

Abstract: The aim of this research was to develop fibrous structures using flax, functionalized with calcium oxide nanoparticles, with degradation properties and antibacterial activity. Flax samples were successfully functionalized with CaO nanoparticles (CaO NPs) and characterized by ATR-FTIR, FESEM, EDX and TGA techniques. ATR-FTIR and FESEM results clearly indicated the presence of CaO NPs in the flax fabrics’ surface. The influence of surface pre-treatments on the effectiveness of the nanoparticles’ deposition was also studied. Three different treatments were used: Alkali, Acetylation and Potassium Permanganate. The alkali treatment presented the best results, therefore, only alkali flax samples were used in UV degradation experiments, as well as antibacterial activity analysis. In order to evaluate the efficiency of the developed systems as agents against chemical and biological warfare, the samples’ organophosphate degradation ability (using DMMP as a GB mimic) was tested, under UV irradiation. ATR-FTIR results indicated that DMMP was successfully degraded by CaO Flax samples. Antibacterial tests were also performed, using the Halo method, which did not yield the expected results, in the range of tested conditions.

Abstract: With concern for chemicals leak in transportation, there is an urgent need for a sensor which can quickly and accurately detect chemicals. In this study, a high-sensitivity gas sensor was demonstrated, which is based on high-field asymmetric waveform ion mobility spectrometry technology with corona discharge (CD) used as the ionization source to product gas-phase ion samples, which can get the response in one second. The effects of dispersion voltage and moisture were investigated.

Abstract: In order to obtain an ideal sample inlet membrane for ion mobility spectrometers (IMS), fumed silica was modified using hexamethyldisilazane and was incorporated into the matrix of polydimethylsiloxane (PDMS) silicone rubber to fabricate PDMS/silica mixed matrix membranes with different thickness. Dimethyl methylphosphonate (DMMP) permeability of thin silicone rubber membranes (SRM) with the least thickness of approximate 5μm was studied. DMMP concentration interior to the SRM showed the linear correlation to that external to the SRM. Thickness and temperature of SRM were two important factors influencing the permeation proportion of DMMP. Most water vapor was prevented to transfer through the SRM. In addition, the SRM had a good selectivity of DMMP/water vapor and the maximum separation factor was 4.82 when the temperature of membranes reached 80 °C.

Abstract: This paper presents new effective approachs for the supermolecule film deposition of surface acoustic wave (SAW) chemical sensors for detecting DMMP. 25-(thioalkyl-alkoxy)-p-tertbutylcalix [4] arene self-assembly molecular imprinted film as the sensitive film was coated on the gold delay line of SAW sensors to detect DMMP. The sensor has special response to organoosphorus compounds and the respond characteristic property in different temperatures of SAW sensor was studied in detail, had important reference value in counter-terrorism.

Abstract: Dimethyl Methyl Phosphonate (DMMP) was synthesized via the MichaelisArbuzov rearrangement in the normal pressure and N₂ atmosphere using a novel and can be used repeatedly catalyst. The preparation conditions of DMMP, such as the reaction time, reaction temperature and catalyst dosage were investigated. The FTIR (Fourier transform infrared spectroscopy), NMR (Nuclear magnetic resonance) , and TG-DSC(Thermogravimetric-Dynamic stability control system) results show that the obtained product is DMMP. When the reaction temperature is higher than 180°C, catalyst dosage is 12 wt%, and the reaction time is about 13 h, the highest yield (78 wt%) of DMMP can be obtained. Then DMMP was added to a FRP (Fiber Reinforced Plastics) matrix. The flame retardancy and mechanical properties of the DMMP/ FRP were tested for Limiting Oxygen Index (LOI), breaking elongation, impact toughness, tensile, and flexural strengths. A significant improvement of flame retardancy of the system was observed (increase of LOI up to 30.4) with an addition of 10 wt% DMMP to FRP. But when the DMMP content in the DMMP/ FRP composites is more than 10 wt%, the comprehensive mechanical properties of FRP will appear to decline and the LOI value has not changed, so we conclude that DMMP content in the DMMP/ FRP composites is 10wt%.

Abstract: This article reports the development of ZnO coated one port Surface Acoustic Wave (SAW) resonators for the detection of DMMP (dimethyl methyl phosphonate), a simulant of chemical warfare agent Sarin at room temperature. For enhanced sensitivity high frequency SAW devices (433Mhz) were used. Frequency shift with DMMP exposure was found to increase with increase in thickness of ZnO film from 20 to 80 nm with maximum shift of 52 kHz. The cross sensitivity of the sensor with commonly available volatile organic compounds (VOCs), gases and water vapors has been performed and was found that the sensitivity towards other interferants is very less as compared to that of DMMP vapors. The sensing mechanism has been explained in detail. It has been shown that there was no significant change in the resistance of the film with exposure to DMMP vapors and hence the contribution of the acoustoelectric interaction is negligible. Further mass loading was not dominant. The negative differential frequency shifts proved that change in elasticity of the film with exposure to DMMP vapors is the dominant sensing mechanism.

Abstract: After the 9∙11 terrorism and America-Iraq war, apprehension of mass destruction weapons such as bio-chemical agents calls for much more sensitive sensors which can detect toxic gases. In this study, semiconductor gas sensors based on tin oxide were examined to detect chemical agent simulants: dimethyl-methyl-phosponate (DMMP), di(propylene glycol) methyl ether (DPGME), acetonitrile, and dichloromethane. DMMP((CH3O)3), DPGME(C7H16O3), acetonitrile(CH3CN), and dichloromethane(CH2Cl2) gases are the simulants of nerve agent-sarin, vesicant agent-HN(N(CH2CH2Cl)3), blood agent-AC(HCN), and choking agent-CG(COCl2) gases, repectively. The SnO2 powder was prepared by a coprecipitation method from the mixture of tin chloride and zinc acetate dihydrate. Zinc oxide was doped into SnO2 from 1 wt% to 4 wt% to improve its reliability and sensitivity. To fabricate a thick film, powders were made into paste with organic binder of ethyl cellulose and screen-printed on the alumina substrate. The phase development and morphology of ZnO-doped SnO2 film were investigated by XRD (X-ray diffraction analysis), BET (surface and pore size analyzer), and SEM (scanning electron microscope). The gas sensing characteristics for target gases were examined with a flow-type measurement system. The concentrations of simulants were controlled from 500 ppb to 1500 ppb, and working temperatures were regulated from 250  to 400 .