Lignin as a green primary antioxidant for polypropylene

Abstract

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. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43558.

High‐density green polyethylene biocomposite reinforced with cellulose fibers and using lignin as antioxidant

“…More recently, cellulose fibers with a residual amount of lignin showed simultaneous reinforcement and stabilization effects for polypropylene and similar results were found for cellulose fiber reinforced polyamide‐6 . Additionally, pure lignin also acted as a primary antioxidant for polypropylene in accelerated aging experiments …”

Impact of lignin extraction methods on microstructure and mechanical properties of lignin‐based carbon fibers

“…[4][5][6] Lignin is the second largest renewable resource in nature only after cellulose, and it is the only renewable resource material containing aromatic rings. 7,8 It is a complex and amorphous polymer with a three-dimensional heterogeneous structure mainly composed of three structural units, which are syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) [see Figure 1(B)]. [9][10][11] These structural units are linked to lignin macromolecules [ Figure 1(A)] mainly by b-O-4 0 linkages.…”

Bio-based additives for thermoplastics

“…The lignin extracted from Eucaliptus grandis, used to produce cellulose by the pulp and paper industry, had its siringyl/guaiacyl ratio determined as 2.1 to 2.5 [59,60] . Formulations containing this lignin showed antioxidant activity for pure polymers and cellulose fiber composites with polypropylene, [61] polyethylene, [62] and polyamide-6 [63] . In the case of polypropylene, aged formulations containing lignin maintained their properties for a longer period in comparison to formulations aged with a non-bio-based antioxidant [61] .…”