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

Abstract

Aiming to manufacture biomaterials using renewable resources, we prepared, using a corotating and intermeshing twinscrew extruder, high-density green polyethylene composites reinforced with 20, 30, and 40 wt % of bleached cellulose fibers. Injection molded test samples are characterized for mechanical and thermal properties using thermogravimetry (TGA) and differential scanning calorimetry (DSC). These composites present improved mechanical properties relative to the pure matrix; the elastic modulus increases by 240% for the composite with 30 wt % of fiber. We characterize this composite, additionally formulated with lignin and a secondary antioxidant, by tensile and flexural mechanical properties, DSC, TGA, and oxidation induction time (OIT). Lignin has no effect on the mechanical properties; however, for the composite, the OIT increases from 24 to 77 min, clearly evidencing its effect as a stabilizer. Aging the composites for 1000 h, in a QUV chamber, confirms the stabilizing effect of lignin.

Presence of iron in polymers extruded with corrosive contaminants or abrasive fillers

“…Composites reinforced with cellulose fibers were processed and obtained as described in previous works: PP [14] , HDPE [15] and PA-6 [16] .…”

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] .…”

“…tris-nonylphenylphosphite and tris-1,3-di-tert-butylphenylphosphite. To the best of our knowledge, presently there are no bio-based secondary antioxidants on the market; however, they were used in a synergistic association with lignin to stabilize polyethylene [62] .…”

Valuable Compound Extraction, Anaerobic Digestion, and Composting: A Leading Biorefinery Approach for Agricultural Wastes

“…However, lignin is becoming a high interesting product. For example given to its radical scavenging properties for the formulation of plastic and cosmetic (Guilhen et al, 2017;Morganti, 2016). Production of low-molecular weight compounds with potential uses as surfactants or additive for liquid fuels can be obtained after lignin fractionation with alcohols (Cabrera et al, 2016).…”