Ms. Silverstein et O. Breuer, WETTABILITY AND FLOTATION OF ETCHED ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBERS, Polymer, 34(16), 1993, pp. 3421-3427
The use of ultra high molecular weight polyethylene (UHMW-PE) fibres i
n composite materials is limited by their poor adhesion to the matrice
s. The wetting of the fibre is an integral step in the adhesion proces
s but the extent of fibre wetting is often difficult to establish. Bot
h surface roughness and surface polarity contribute to fibre wettabili
ty. A flotation method has been used to study the wettability of chemi
cally-etched UHMW-PE fibres. The flotation is defined by the percentag
e of fibres that float on a liquid flotation medium. The dependence of
flotation on surface tension exhibits a float/sink transition that ca
n be used to characterize the effects of surface roughness and surface
oxidation. Chromic acid removes an oxygen-rich skin on the as-receive
d fibre surface, increases surface roughness and oxidizes the UHMW PE
yielding an increase in apparent surface tension.