Papers by Keyword: Chemical Concentration

Abstract: For the direct measurement of chemical concentrations of substances in process liquids, sensors need to be fast and reliable. We investigated the usability of hydrogels as sensitive coating materials for piezo-electric thickness shear mode resonators. Hydrogels are cross-linked polymer networks that show well-defined shifts of their degree of swelling upon changes of environmental parameters such as ionic concentrations, concentrations of organic solvents or temperature. These changes of gel properties are then transferred into an electrical signal. The novel sensor solution exhibits response times of only few seconds and matches the reliability of innovative process measuring technology. A method for its application specific adaption is presented. It is based on optimizing the interrelation of the sensor structure, the manufacturing technology for the hydrogel layer, and the processing of the measured data. The performance of the method is illustrated with the example of a PVA/PAAhydrogel coated sensor which monitors the concentration of a cleaner used in surface technology. The developed measurement device for this application was approved with a measurement error of less than 5 %.

Abstract: Natural fiber composite is nowadays used as an alternative to conventional materials. In this work, the natural fibre, Reshira is tried with epoxy resin, for the first time, as a composite material to be used for various applications. The reshira fiber is chemically treated with sodium hydroxide for better adhesion between fibre and resin. The reshira fiber–epoxy composite is fabricated with varying chemical concentrations of sodium hydroxide solution, fiber lengths and fiber volume fractions. The composite samples are subjected to tensile, flexural and impact tests and the optimum composition that produces maximum mechanical performance is selected. Further the optimum sample is tested for its fracture toughness property.

Abstract: Natural fiber composite has already proved its worth in various mechanical applications. Natural fibres with attractive properties such as low density, environment-friendliness and less processing work are widely available and provide an alternative to the conventional fibres. In this paper, the fibre reshira has been tried for the first time for cryogenic applications. Initially, the fibre is given chemical treatment with sodium hydroxide solution to enhance the adhesion between the fibre and the resin. The treated fibre is reinforced with epoxy resin and its properties such as storage modulus, loss modulus and Glass Transition Temperature are evaluated both at room temperature and under cryogenic conditions and these are compared to see which condition produces better mechanical performance.