Characterization of rheological and thermophysical properties of HDPE–wood composite

The objective of this study is to develop a new biocomposite material with high deformation ability. In this regard, the thermal, rheological, and thermophysical properties of this new composite were characterized as a function of temperature and filler concentration. High density polyethylene (HDPE) was the matrix of this new composite which was reinforced with six sawdust con- centrations 0%, 20%, 30%, 40%, 50%, and 60%. Maleic anhydride grafted polyethylene (PE-g-MA) was used as coupling agent. Addi- tion of sawdust with PE-g-MA increased significantly the complex viscosity, the storage modulus (G 0 ), and loss modulus (G 00 ) of the matrix. The superposition of the complex viscosity curves using temperature dependent shift factor, allowed the construction of a vis- cosity master curve covering a wide range of temperatures. Arrhenius law was used for the relationship of the shift factor to tempera- ture. Furthermore, method of Van Gurp and Palmen (tan delta vs. G*) is also used to control the time-temperature superposition. The experimental results can be well fitted with the cross rheological model which allowed the prediction of the thermorheological properties of the composites over a broad frequency range. By increasing wood concentration, both the activation energy and relaxa- tion time for the biocomposites determined using, respectively, the Arrhenius law and the cole-cole rule increased. By contrast, spe- cific heat of the matrix decreased with sawdust addition while its dimensional stability improved. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40495.