圧力センサ法による布面に垂直な吸水の測定とその解析

抄録

A pressure sensor method was developed in order to measure spontaneous water uptake perpendicular to fabric plane. Water absorption was detected by a pressure sensor which was placed at the bottom of a water reservoir. Using this apparatus, water absorption of some types of woven fabrics was measured. Relation between water absorption, M (t) (g/cm²) and square root of time elapsed, t (s) is well fitted by first order regression equation. From this relation, water absorption rate constant k_??_ (g/cm2√s) can be obtained and water absorptivity can be evaluated using k_??_ and M_max (g/cm²), maximum water absorption. Based on the measurement of mean pore diameter by bubble point method, it is shown that water absorption perpendicular to fabric plane does not follow Washburn's law. Water absorption phenomena is explained well by non-linear diffusion equation and the fact that M (t) is regressed well by √t is also explained by this model. If open pore structure between fibers is modelled by lattice space and water flow by capillary action is considered to be random walk within this network, it is understandable that water absorption perpendicular to fabric plane can be explained by diffusion model. The transport mechanism is different between in-plane capillary water flow reported in a previous paper and water absorption perpendicular to fabric plane reported here. Therefore, it is considered that water absorptivity has to be estimated for each direction, i.e. parallel and perpendicular to fabric, respectively.