Blends of Nylon 6 (Ny6) and polyolefins functionalized with acrylic acid (polyethylene-PE-AA, polypropylene-PP-AA) were investigated in terms of crystallization behavior and resulting Ny6 crystalline structure. Thermal analysis showed that in the case of blends with functionalized polyolefin as a matrix: (a) Ny6 crystallization is spread and dramatically shifted toward lower temperatures, approaching that of the polyolefin component 125-132 degrees C; (b) Ny6 gamma crystal polymorph is the major phase present; confirmed and quantitatively evaluated by use of deconvolution computations performed on WAXS spectra of the blends. When Ny6 is dispersed in functionalized polyolefin matrix, the weight content of Ny6 gamma crystals increases up to three times with respect to analogous, non-compatibilized blends and up to approximate to 16 times with respect to Ny6 homopolymer. These phenomena are explained by the reduction of size of Ny6 dispersed particles, caused by the interactions between the functional groups of polyolefin and the polar groups in polyamide chain. The nucleation mechanism is changed due to the lack of heterogeneous nuclei in most small Ny6 droplets, which results in the enhanced gamma crystal formation. (C) 2000 Elsevier Science Ltd. All rights reserved.