Green chemicals and process to graft cellulose fibers.

The treatment of additive-free hand sheet paper samples with cold plasma was carried out and showed that cellulose can be chemically linked with reactive natural products, namely myrcene (My) and limonene (LM). Contact-angle measurement and X-ray photoelectron spectroscopy (XPS) were used to ascertain the occurrence of the grafting. Indeed, the contact-angle value of a drop of water deposited at the surface of paper increased from 30 degrees for unmodified substrate to about 105 and 107 degrees, for LM- and My-treated samples, respectively. In fact, LM- and My-treated surfaces were rendered totally apolar. Indeed, the polar contribution to the surface energy decreased from about 23 mJ/m(2) for pristine samples to practically zero for treated ones. The treated surfaces displayed water-barrier properties; the penetration of the liquid was reduced significantly after LM and My treatments. The XPS spectra showed that the modification with LM and My gave rise to very significant change in the O/C ratio, as well as in the intensity of the C1 peak assigned to aliphatic carbon sequences.