Graft polymerization of N-isopropylacrylamide (NIPAAm) onto cotton cellulose preirradiated in air by ,60,Co γ rays was accomplished in mixed solvents of water and alcohols or acetone. The graft yields changed with different ratios of water and organic solvents. In the system of solvents comprised of water and methanol, the Trommsdorff effect appeared in the curve of the graft yields vice verse the concentrations of the monomer. In the same system, the dependence of the graft yield of NIPAAm on the graft temperature was different from that of Acrylamide (AAm). The relation between the graft yields of the grafted products and their crystallinities measured by X Ray Diffraction could be regarded as a proof of the 'third phase' conception.