电容式湿度传感器电容式湿度传感器——交联的聚甲基丙烯酸甲酯的感湿性能

运用本体聚合法合成了聚甲基丙烯酸甲酯（ＰＭＭＡ）和分别用三种交联剂交联的ＰＭＭＡ。以ＰＭＭＡ和交联的ＰＭＭＡ为感湿膜制成电容式湿度传感器,在１０％～９０％ＲＨ范围内,这些传感器的电容随相对湿度呈线性规律变化。交联的ＰＭＭＡ传感器具有正的温度系数,但与乙酸丁酸纤维素（ＣＡＢ）传感器相比,ＰＭＭＡ的温度依赖性更小。交联的ＰＭＭＡ传感器能耐有机蒸气,在饱和丙酮蒸气中放置３０ｍｉｎ后,３次测试循环后在９０％ＲＨ下传感器电容的变化约为１％。在高温、高湿、油烟气等各种苛刻环境中放置预定时间后,传感器的漂移一般在±２％ＲＨ范围内。

A Capacitivetype Humidity Sensor Humiditysensitive Properties of Crosslinked Poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA) and three kinds of crosslinked PMMA were synthesized by bulk polymerization.Capacitivetype humidity sensors were prepared with PMMA and crosslinked PMMAs films respectively.The electrical capacitance of the sensors changed linearly with the relative humidity over the range of 10%90% RH.The crosslinked PMMA has positive temperature coefficient.When compared with the cellulose acetate butyrate(CAB) sensor,however,the temperature dependence of PMMA is less.Crosslinked PMMA sensor is resistant to organic vapour.After exposure to saturated acetone vapour for 30min,the electrical capacitance of the sensor changed ca 1% at 90% RH after three measurement cycles.Under various severe conditions,e.g.hightemperature,highhumidity,oil vapour ect.,the sensor showed about 2% RH drift after the tests.