The Compound Design And Research Of Capacitive Humidity-sensitive Properties Of PI And CAB

Polymer capacitive humidity_sensitive material has become the promising material for making humidity_sensitive sensors. As one kind of the capacitive humidity_sensitive materials PI has disadvantages of a negative temperature coefficient and a protrude output while CAB has disadvantages of a positive temperature coefficient and a concave output. In order to make use of the advantages of high sensitivity and low humidity-sensitive hysteresis and achiecve matual assist, the author presents the consideration of making compound sensors and the final intention is to develop humidity_sensitive sensors with good humidity sensitivity and give the base for the research of humidity_sensitive sensors. This auther has obtained one of PI family with phenyl through two-step method and has done many research about the reation, the conditions of this reation.After having made sensors with PI, he tested the main humidity properties of PI and the influence of many factors to PI sensors. And then he did with CAB-55-1 with the same ways.Based on the humidity Properties of PIand CAB, two different kinds of compound sensors were designed. By testing, it is excited to find that the compound sensors have superior humidity Properties to PI and CAB. This paper has also researched the influence of many factors to CAB+PI and CAB/PI sensors. The testing result reveals that the CAB+PI sensors has such excellent Properties with response time of 4.3S, sensitivity of 0.3987PF/ % RH , humidity-sensitive hysteresis of 2.01 % RH , a negative temperature coefficient of -0.0753%RH/℃and a linear output.Furthermore, the paper also presents the making process, humidity-sensitive machenism and the osmosis of moisture to polymer.