The first two articles were concerned, (1) with the preparation and, (2) with the water retention properties of the grafted cellulose. This articel presents some physical, mechanical, and ion exchange properties. Bleached sulfite softwood puplp filter paper was the substrate and polyacrylic acid the grafted side chains. The thickness of the paper increased with grafting accompanied by a decreased in area, particularly in the machine direction. The air permeabilities of the grafted papers were essentially unchanged even at high degrees of grafting. The dry tensile strength increased somewhat with grafting but the zero span strength decreased. Wet tensiles increased considerably up to about 50% graft, but then decreased. The wet elongations, however, steadily increased but began to level off at 120% graft. Strength properties were also measured with melamine wet strenghened paper. The ion exchange capacities of the dispersed paper pulp indicated that all the grafted polyacid groups were rapidly utilized.