Several fiber surface treatment methods have been studied to
improve the adhesion between coconut fibers and the surrounding
matrix, as well as, to reduce water absorption and increase
mechanical properties. Nowadays, effective methods based on
chemical treatment4,5 such as dewaxing and grafting are used to
increase the surface area available for contact with the matrix,
but these methods are expensive (like silane agents) and they may
cause serious damage to the environment (acids or alkalis agents).
Alkalization is the main technique used on natural fiber to remove
hemicelluloses6 of fiber surfaces and it has been employed as a less
harmful treatment to the environment and cheaper than other methods
proposed. However, its use is still controversial, some are favorable
others suggest controlled application8 mainly due to chemical wastes
generated. Physical treatments (cold plasma treatment, corona
treatment)9,10 have been proposed as eco friendly processes for
superficial modification of the fibers, but these are usually complex
and very expensive methodologies. Research on an effective low
cost treatment of natural fibers is necessary since the cost of the
raw material, i.e. the natural fiber, is very attractive to the market.
Some studies have been carried out on photo-induced grafting onto
cellulose11-13 employing UV radiation. Rahman and Mubarak14, for
instance, applied artificial UV radiation as a pretreatment on coconut
fibers reinforced polymethacrylate matrix. The authors observed an
increase in the tensile properties and they attributed this effect to
the inter-crosslinking between the neighboring cellulose molecules
that occurs under UV radiation. The surface topography is entirely
modified after this treatment suggesting that a mechanical treatment
could successfully enhance fiber–matrix adhesion. Although the
combination of mechanical and UV radiation treatments represents
a new and simple proposal that can be employed to enhance physicomechanical properties of coconut fiber composite based on polymeric
matrix, no study has been reported up to now.