PREPARATION OF AN ULTRAFAST WATER DISTRIBUTED SENSOR BASED ON POLYVINYLAMINE COMPOUNDS AND Cu(II) SALTS

• DOI: 10.22533/at.ed.31733223220910

• Palavras-chave: Water, Distributed sensors, Leakages

• Keywords: Water, Distributed sensors, Leakages

• Abstract: The question of water economy is becoming a critical problem in urban centers and in agricultural districts due to the increasing shortage of this essential resource (1-6). Specially, leakages from water pipes are the object of much attention from administrations and companies in charge of water supply. However, considerable efforts are still necessary to ensure adequate water supply to the population. Among many similar examples, the case of Mexico City is interesting since the loss of water through leakages in this capital is about 25 % of the total amount of the water consumption. Of course, similar problems are worldwide, and them have received insufficient attention in the past. Due to the dramatic water shortage in many regions of the world, the development of efficient water leakage sensors become a high-priority issue. In order to safeguard an extensive network of water pipes, a "distributed" design is a cheap and reliable solution for the detection and pin-pointing of water leaks. A linear sensor is placed along the pipe that contains: i) A polymeric material whose electrical properties change when it enters in contact with water, ii) an electrical conductor that senses the change in the material property and, iii) a distant monitoring system that measures the position of electric perturbation. When a leak occurs near the sensor, water permeates into the material and its electrical resistance drops. This effect triggers an alarm which warns the monitoring system that a leak has occurred and alerts of a leak. In order to produce sensors as the ones described above, Poly (vinyl amine) (PVAm) hydrogels can be currently employed. Poly (vinyl amine) (PVAm) is a polymer with interesting properties for those purposes. Indeed, when softly cross-linked PVAm becomes a hydrogel that is capable of absorbing a large quantity of water without dissolving. This polymer can be cross-linked employing a method based on a chelating reaction with copper ions. The coordinated covalent bonds formed between the Cu2+ ions and the amine groups of PVAm produce chain junctures that conferee it certain properties such as: i) significant swelling upon water absorption, ii) resistance to dissolution in water, iii) ability of extrusion processing, iv) excellent thermal and chemical stability and, v) low electric resistivity in the wet state. We have taken advantage of those properties to design distributed water sensors with ultra-fast response, which may be utilized for the detection of leakages along water pipes, as well as to monitor places that must be free of water leaks as; libraries, electrical control centers, boats, ships, submarine facilities, etc.