Lignin as a green primary antioxidant for polypropylene

Lignin and Irganox 1010, a hindered phenol antioxidant, are compared as a primary stabilizer in formulations for polypropylene ( PP) by exposition to accelerated aging. The concentration of lignin was adjusted to match the concentration of hindered phenolic groups of the commercial stabilizer. Upon aging, lignin formulation retains the initial mechanical properties longer than the formulation with Irganox 1010. The ratio of the areas of the carbonyl and the hydroxyl infrared absorption bands is proposed as a method to evaluate the photodegradation process. In this aspect, the formulation with lignin also presents better results than the formulation with Irganox 1010. There are two hypotheses for the best performance of lignin in the studied conditions: lower leaching of lignin, due to its crosslinked nature, and leaching of low molar mass products of Irganox 1010 hydrolysis. These results indicate lignin, from the Kraft process of Eucalyptus wood, as a promising green substituent to synthetic hindered phenol stabilizers. (C) 2016 Wiley Periodicals, Inc. (AU)