Studies on PVP, PVA and their nAg composites based humidity sensors

The nAg/PVP and nAg/PVA composites were synthesized by using chemical reduction method. The neat Poly vinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) at different concentrations and their nano metal polymer composites were studied for electrical humidity sensing, ranging from 5-90% RH. The neat polymers and their composites were coated on ceramic rods having built in electrodes by drop casting method. With increase in concentration, there is an increase in resistance by an order of magnitude. The PVA and PVP at 0.1% wt of polymer show large change in magnitude of resistance with humidity in the range 5-90 %RH hence is used for further studied for electrical humidity sensing. The formation of nAg/polymer composite is decided from data of UV-Visible. The nAg/polymer composites are characterized by UV-Visible, DLS and FTIR (at 5% and 85% RH). Samples of nAg/0.1% PVP show good sensitivity over a wide range of humidity (5-90% RH) as compared to nAg/0.1% PVA. The nAg/0.1% PVP has fast response and recovery, good repeatability and reproducibility as compared to nAg/0.1% PVA.