It is examined whether useful information on plant fiber surfaces can be re
trieved from wetting experiments such as dynamic contact angle (DCA) analys
is by use of the Wilhelmy technique and the Lifshitz-van der Waals acid-bas
e theory. It is argued from a theoretical point of view that plant fibers m
ay give rise to various complex phenomena during wetting experiments, pheno
mena which are typically not found for synthetic fibers, and that these phe
nomena can be a source of invalidation of experimental techniques which are
commonly thought to supply information on equilibrium (or quasi-equilibriu
m) properties of plant fiber surfaces or of surface-liquid interactions, Th
e nonequilibrium phenomena are studied experimentally by DCA analysis of 10
sisal fibers, 10 coir fibers, and 5 polyacrylate-coated glass fibers. The
fibers are immersed in deionized water at 10 different speeds ranging from
2 to 100 mum s(-1) and the relationship between immersion speed and contact
angle is examined, In contrast to what is found for the coated glass fiber
s, the results indicate that the (aqueous) wetting behavior of sisal and co
ir fibers is qualitatively far from the behavior which should ensure the me
aningful interpretation of the wetting data as (quasi-)equilibrium data. Fr
om both a theoretical and a practical basis it is hence concluded that none
quilibrium phenomena necessitate a more severe form of precaution toward su
rface energy component theories when these are used for interpreting plant
fiber wetting than what is currently at issue. (C) 2001 Academic Press.