Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Biocomposites based on cellulose acetate and short curaua fibers were prepared by extrusion on a laboratory scale. The influence on the mechanical and thermal properties of the biocomposites caused by three different plasticizers, dioctyl phthalate (DOP), triethyl acetate (TEC) and glycerol triacetate (GTA), and the chemical treatment of the fibers was evaluated. The fibers were mercerized or extracted with acetone. The efficiency of the plasticizers was determined by their molecular features, however, for some applications DOP can be replaced by less hazardous plasticizers, such as TEC and GTA. The biocomposites presented morphology of fibrils uniformly dispersed in the polymer matrices and higher Young's modulus, higher thermal dimensional stability and lower thermal conductivity in comparison with the properties of the corresponding plasticized polymer matrices. Moreover, these biocomposites combine mechanical and dimensional properties of dense materials with thermal conductivities of porous and thermally insulating polymers. (C) 2012 Elsevier Ltd. All rights reserved.43813381346Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)PET-ROBRAS [11 P-06662-2008]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2010/17804-7, 2010/2098-0]PET-ROBRAS [11 P-06662-2008]