固体与液体接触角的测定

Measurement About Contact Angle Between Solid and Liquid

当把毛细管插入石蕊水溶液时 ,由于液体表面张力和浸润现象共同作用的结果 ,产生了毛细现象 ,液面呈凹球面。从凹球面与固体表面切点分别作这两个面的切线 ,这两条切线通过液体所成的角度称为接触角。根据朱仑公式 ,接触角决定于液体的密度 ρ、液体表面张力系数α、液柱高度h、毛细管的半径r以及重力加速度 g。液体密度值近似取 ρ =10 0 0kg/m3 ,表面张力导数直接采用焦利称实验测量的结果α =(6 .6 5± 0 .0 5 )× 10 -2 N/m重力加速度直接采用单摆实验的测量结果 g =(9.6 5± 0 .0 6 )m/s2 。而使用读数显微镜直接测量彩色液柱上下两个面的坐标 y1,y2 和左右两侧的坐标x1,x2 来计算液柱高度h =y2 - y1和毛细管半径r=(x2 -x1) / 2。利用朱仑公式给出了固体和液体接触角的间接测量结果和不确定度的评定结果 。

When capillarimeter is inserted into litmus water solution, the capillary is produced by actions of surface tension of liquid and infiltration, the surface of the liquid is the concave spherical surface. Drawing two tangent lines at the point of tangent of the concave spherical surface and at one of the solid surface, respectively, the angle formed by the two lines in the liquid is called contact angle between the solid and the liquid. According to Julian formula, the contact angle is decided by the density of liquid ρ ,the coefficient of surface tension of the liquid α,the height of the liquid cylinder h ,the radius of capillary r as well as acceleration of gravity g.The ρ=1 000 kg/m 3 was taken as the approximate value of density of the liquid , the experimental result α=(6.65±0.05)×10 -2 of Jolly balance experiment was taken as the coefficient of surface tension. The experimental result by simple pendulum experiment g = (9.65±0.06)m/g 2 was taken as the acceleration of gravity, and the coordinates of upper face and lower face x_1,x_2, the coordinates of right side and left side of color liquid cylinder y_1,y_2 were read from microscope in order to calculate the height of liquid cylinder h = y_2 -y_1 and the radius of capillarimeter r = (x_2 -x_1)/2.By using Julon formula, the indirect measuring result of the contact angle of the solid and liquid and the uncertainly evaluation were given. The experimental result is discussed.