Gita Šakale

The investigation of sensing mechanism of ethanol vapour in polymer-nanostructured carbon composite

Polymer-nanostructured carbon composites (PNCC) using three different polymers as composite matrix materials (polyvinylacetate (PVAc), polyethylene glycol (PEG) and ethylene-vinylacetate copolymer (EVA)) have been developed. High structure carbon black Printex XE2 (Degussa AG) was used as a composites filler. Ethanol vapour sensor-effect of composites was determined as a change of electrical resistance as the composite was held in ethanol vapour for 30 seconds. Reversibility of electrical resistance of PNCC, response stability and repeatability have been measured and compared. The electrical resistance response of EVA-nanostructured carbon composite (EVA-NCC) to ethanol vapour as a function of vinylacetate content in the copolymer has been evaluated. Promising ethanol vapour sensor-effect has been observed for PEG-NCC followed by PVAc-NCC and EVA-NCC.

Comparison of effects on crustaceans: carbon nanoparticles and molybdenum compounds nanowires

Carbon nanomaterials (CNM) and molybdenum compound nanostructures are materials with various applications yet little is known regarding the toxicity of these nanoparticles in pristine form in aquatic environment. Daphnia magna standard acute toxicity test (EN ISO 6341:1996; freshwater) and Artemia salina standard acute toxicity test (ArtoxKit standard method; 15 ppt saltwater) were applied to assess the toxicity of non-modified CNM and molybdenum compound nanowires in water. It has been observed that CNM are more toxic in freshwater suspensions and somewhat more toxic than the tested molybdenum compound nanowires.

Effect of Nanotube Aspect Ratio on Chemical Vapour Sensing Properties of Polymer/MWCNT Composites

The main topic of this paper is the study of polyisoprene-multi wall carbon nanotubes (PiMWCNT) composites electrical conductivity and volatile organic compound sensing properties with respect to type of multi wall carbon nanotubes used. Electrical percolation parameters like percolation threshold and critical exponent of produced composites are determined and analyzed. PiMWCNT composites exhibit a promising sensitivity to the presence of volatile organic compounds. Therefore the composites sensing mechanism of volatile organic compounds are analyzed in more detail by applying an original measuring technique which enables simultaneous measurement of an electrical resistance, mass and length change measurement of the sample in the presence and subsequent absence of a vapour. Measurement results enabled the evaluation of both vapour diffusion behavior in the composite and electrical resistance change mechanism.

BTEX detection with composites of ethylenevinyl acetate and nanostructured carbon

By using a solvent-based method composites of ethylenevinyl acetate copolymer and carbon black (EVA–CB) were synthesized for sensing BTEX (benzene, toluene, ethylbenzene and xylene) vapours. The composites were characterized using atomic force microscopy (AFM) in an electroconductive mode. Gas sensing results show that EVA-CB can reproducibly detect BTEX and that the response increases linearly with vapour concentration. Compared to gas-sensing measurements of gasoline vapours, the responses with toluene and ethylbenzene are different and can be explained by varying side chains of the benzene ring.

Ethylene vinylacetate copolymer and nanographite composite as chemical vapour sensor

Polymer-nanostructured carbon composite as chemical vapour sensor is described, made by the dissolution method of a non-conductive polymer, ethylene vinylacetate copolymer, mixed with conductive nanographite particles (carbon black). Sensor exhibits relative electrical resistance change in chemical vapours, like ethanol and toluene. Since the sensor is relatively cheap, easy to fabricate, it can be used in air quality monitoring and at industries to control hazardous substance concentration in the air, for example, to protect workers from exposure to chemical spills.