Effects of Kraft lignin and corn cob agro-residue on the properties of injected-moulded biocomposites

• Published in: Industrial crops and products Vol. 177; p. 114421
• Main Authors: de Baynast, Hélène, Tribot, Amélie, Niez, Benjamin, Audonnet, Fabrice, Badel, Eric, Cesar, Guy, Dussap, Claude-Gilles, Gastaldi, Emmanuelle, Massacrier, Laurent, Michaud, Philippe, Delattre, Cédric
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2022; Elsevier
• Subjects: Biopolymer; Chemical and Process Engineering; Engineering Sciences; Environmental degradation; Food engineering; Life Sciences; Mechanical properties; Microstructure; Natural fibres; Thermal analysis; Vegetal Biology; Mechanical properties; Natural fibres; Thermal analysis; Microstructure; Environmental degradation; Biopolymer
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2021.114421

Lignocellulosic by-products are frequently disposed by means of combustion. This study investigates an alternative route for corn cob and Kraft lignin resources in order to support circular economy. The respective plant-based fibres and filler were compounded for the first time together with a poly(lactic acid) (PLA) matrix. Consecutively, seven different biocomposites were processed by injection-moulding and further characterized. The biocomposite containing a mixture of Kraft lignin and corn cob (12 wt% in total) exhibited the highest flexural strength (84 MPa). A proper wetting of PLA onto the corn cob particles demonstrated a good compatibility at matrix/fibre interface. PLA molecular structure changed in presence of 20 wt% lignin filler, with effect on the glass transition temperature and on the composite mechanical strength. The fibres moderately influenced composites surface tension, while Kraft lignin contributed to a slight increase of surface hydrophobicity. Surface energy (σsTotal) of composites have been estimated at 27.6, 28.7 and 27.8 mN/m for PLA/KL-20, PLA/CC-10 and PLA/KL-15/CC-5 respectively. While the polar component (σsPolar) have been estimated at 17.8, 20.0 and 18.7 mN/m for PLA/KL-20, PLA/CC-10 and PLA/KL-15/CC-5 respectively. Unlike the PLA/corn cob composite, those containing Kraft lignin were entirely biodegraded within 2 months in industrial composting conditions study. The materials could be utilized for end-use products thanks to their good mechanical and thermal properties. By adding wood-lignin and corn by-products, materials cost and carbon footprint shall decrease in comparison to pure PLA, while being a biodegradable and sustainable replacement of polyolefins. [Display omitted] •Decreasing cost and carbon footprint of poly(lactic acid) (PLA) materials.•PLA was filled with corn cob by-products.•Conventional twin-screw extrusion and injection-moulding methods were employed.•Biocomposites properties were satisfying enough to apply them into end-products.•Kraft lignin-filled materials fully biodegraded in industrial compost within 60 days.