Dynamic mechanical characterization of epoxy-based thermosetting materials loaded with lignin

One of the key-aspects to promote sustainability in the biofuels industry is concerned with the recycling processes of its residues. In this sense, a consolidated method of reusing such residues is given by their incorporation in polymeric and composite materials. Designing these materials is compelling inasmuch as one may target desired properties such as low density and low cost. This work aims at proposing a methodology of experimental characterization and modeling of the thermomechanical behavior of epoxy-based composites with 0, 1 and 5 wt.% of lignin which is one of the main residues of the biofuel industries. Experimental measurements are carried out in a dynamic mechanical analyzer to evaluate the effects of both temperature and frequency on the thermomechanical behavior of the composites. The glass transition temperature and the complex modulus are obtained for different lignin percentage levels. The time–temperature superposition principle is employed to generate experimental master curves to observe the long-term viscoelastic behavior. Then, the five-parameter fractional derivative model is calibrated by means of the nonlinear least squares method. Time-domain predictions under general loading conditions are provided for different temperatures.