Composites of linear low-density poly(ethylene-co-butene) (PE) or maleated linear low-density poly (ethylene-co-butene) (M-PE) and cellulose (CEL), cellulose acetate (CA), cellulose acetate propionate (CAP), or cellulose acetate butyrate (CAB) were prepared in an internal laboratory mixer with 20 wt % polysaccharide. The structure and properties of the composites were studied with tensile testing, dynamic mechanical thermal analysis, differential scanning calorimetry, extraction with a selective solvent, Raman spectroscopy, and X-ray diffraction. Composites prepared with M-PE presented yield stress and elongation values higher than those of composites prepared with PE, showing the compatibilizer effect of maleic anhydride. Dynamic mechanical thermal analysis performed for M-PE-CEL, M-PE-CA, M-PE-CAP, and M-PE-CAB composites showed one glass-transition temperature (T-g) close to that observed for pure M-PE, and for M-PE-CAP, another T-g lower than that measured for the polysaccharide was observed, indicating partial mutual solubility. These findings were confirmed by the extraction of one phase with a selective solvent, gravimetry, and Raman spectroscopy. X-ray diffraction showed that the addition of CEL, CA, CAP, or CAB had no influence on the lattice constants of PE or M-PE, but the introduction of the reinforcing material increased the amorphous region. (c) 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:402-411,2007