ozonization is a very efficient, economical, and potentially practical method to modify polypropylene (pp) as well as polyethylene (pe) surfaces. carbonyl, carboxyl, and hydroperoxide groups can be very conveniently generated by reacting these polymers with ozone. in the case of fibers and powders, surface treatment with ozone in an aqueous medium offers advantages: water can be used as a carrier in commercial processes, and since water enhances generation of hydroperoxide it may be used for potential reaction purposes. the extent of reaction of polyolefins with ozone depends on the extent of agitation of the slurry, the slurry temperature, solid consistency, and ozone concentration in the gas. within the limits of the present work, the ozone uptake of fibers increases linearly with time. the surface of both ozonized and grafted pulps becomes highly hydrophilic. polyethylene, in the limited results obtained in this work, behaves very similarly to polypropylene. the activation energy of ozone reaction with both polypropylene and polyethylene is approximately 7 kcal/mol. (edited author abstract) 23 refs