Blends based on LDPE and cellulose or ethylcellulose were prepared under high-temperature shear deformations in a rotor disperser at different initial ratios of the components. The composition of powder fractions was identical to the initial composition of the blends. The studied polymer blends demonstrated high mechanical characteristics. X-ray diffraction analysis showed that the blending of LDPE with cellulose and ethylcellulose under conditions of shear deformation results in changes in the polymer structure and leads to a decrease of their crystallinity. The peculiarities of thermal degradation of the obtained blends were discussed in detail. The observed results were interpreted by the model kinetic analysis based on TGA. (C) 2011 Elsevier B.V. All rights reserved.