Graft copolymerization of vinyl monomers onto modified cottons. XII. Grafting of 1,1‐dihydroperfluoroheptyl acrylate onto cellulose carbamate using hydrogen peroxide as initiator

Abstract

AbstractCellulose carbamate having 1.4% N was grafted with 1,1‐dihydroperfluoroheptyl acrylate (DHPFHA) using H2O2 as initiator under a variety of conditions. The technique used involved padding the fabric in H2O2 solution at room temperature followed by impregnating it in an aqueous emulsion of DHPFHA. The graft yield, expressed as fluorine percent, was found to depend upon monomer and initiator concentration, temperature, and reaction time and pH of the polymerization medium as well as upon the carbamate content of the modified cotton. Increasing the monomer concentration up to 5% caused a considerable enhancement in grafting. The same holds true for initiator concentration up to a certain limit after which the grafting decreases. Raising the reaction temperature up to 100°C was accompanied by an increment in the magnitude of grafting reaction. The latter was characterized by an initial fast rate followed by a slower rate. Slightly acidic media (pH 5–6) proved to be the best for performing grafting. The graft yields were quite poor when grafting was carried out in acidic (pH 2–4) or alkaline (pH 8–12) media. The presence of a relatively smaller amount of carbamate groups in the cellulose molecules decreases its susceptibility to grafting. The opposite holds true for larger amounts. Incorporation of FeSO4 at low concentration in the monomer emulsion had no effect on the graft yield. However, the latter decreases at higher FeSO4 concentration. Grafted cellulose carbamate having ca. 15% fluorine showed very good oil and water repellency. The grafted product retained ca. 85% of the strength of cellulose carbamate.