THE STUDIES OF DETERMINING CONTACT ANGLE OF FIBERS AND POWDER FILLER BY THE DYNAMIC METHOD OF WICKING

This pager studies on the effect of surface treatment on the wettability of fibers by the dynamic method of wickiag.The results show that the wettability has got a great improvement after the fiber surface is treated by cold plasma.That is because oxygen-containing groups (-COOH,=C-OH and =C=O).are introduced onto the surface.At the same time,the contact angle of fiber/water has been calculated by messuring the difference of surface free energy (Δr) during the wetting process,which is close to the results obtained by using contact angle meter with tilting plate method.After the treatment,it can be seen from the measurement of contact angles that the wettability has been improved,For instance,the eontact angle of carbon fibers/water has been decreased from 17°to 83°and polyester fibers/water from 77°to 52°after they are treated by cold plasma oxygen.Besides,the wettability of water to coal powder system and to glass powder system are studied.It is found that the ettabilty of water/glass powder is better than that of water/coal powder,The wetting contact angle of the former is 47°and the later is 90°.These values of contact angle are also correspondent to those between water and flakes,which are measured by the use of contact angle meter in sessile drop method,From those aforementioned,it's clear that the dynamic method of wicking can be used to measure the wettability of fibers and powder systems,while its operation is easy and only takes a short period.